Antigenic Variation: Change in the surface ANTIGEN of a microorganism. There are two different types. One is a phenomenon, especially associated with INFLUENZA VIRUSES, where they undergo spontaneous variation both as slow antigenic drift and sudden emergence of new strains (antigenic shift). The second type is when certain PARASITES, especially trypanosomes, PLASMODIUM, and BORRELIA, survive the immune response of the host by changing the surface coat (antigen switching). (From Herbert et al., The Dictionary of Immunology, 4th ed)Genetic Variation: Genotypic differences observed among individuals in a population.Variant Surface Glycoproteins, Trypanosoma: Glycoproteins attached to the surface coat of the trypanosome. Many of these glycoproteins show amino acid sequence diversity expressed as antigenic variations. This continuous development of antigenically distinct variants in the course of infection ensures that some trypanosomes always survive the development of immune response to propagate the infection.Genes, Protozoan: The functional hereditary units of protozoa.Trypanosoma brucei brucei: A hemoflagellate subspecies of parasitic protozoa that causes nagana in domestic and game animals in Africa. It apparently does not infect humans. It is transmitted by bites of tsetse flies (Glossina).Trypanosoma: A genus of flagellate protozoans found in the blood and lymph of vertebrates and invertebrates, both hosts being required to complete the life cycle.Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Protozoan Proteins: Proteins found in any species of protozoan.Babesia bovis: A species of protozoa that is a cause of bovine babesiosis. Ticks of the genera Boophilus, Rhipicephalus, and IXODES are the chief vectors.Antigens, Protozoan: Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.Fimbriae Proteins: Proteins that are structural components of bacterial fimbriae (FIMBRIAE, BACTERIAL) or sex pili (PILI, SEX).Neisseria gonorrhoeae: A species of gram-negative, aerobic bacteria primarily found in purulent venereal discharges. It is the causative agent of GONORRHEA.Borrelia: A genus of gram-negative, anaerobic, helical bacteria, various species of which produce RELAPSING FEVER in humans and other animals.Trypanosomiasis: Infection with protozoa of the genus TRYPANOSOMA.Epitopes: Sites on an antigen that interact with specific antibodies.Antigens, Viral: Substances elaborated by viruses that have antigenic activity.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Bacterial Outer Membrane Proteins: Proteins isolated from the outer membrane of Gram-negative bacteria.Plasmodium falciparum: A species of protozoa that is the causal agent of falciparum malaria (MALARIA, FALCIPARUM). It is most prevalent in the tropics and subtropics.Recombination, Genetic: Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.Host-Parasite Interactions: The relationship between an invertebrate and another organism (the host), one of which lives at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Giardia lamblia: A species of parasitic EUKARYOTES that attaches itself to the intestinal mucosa and feeds on mucous secretions. The organism is roughly pear-shaped and motility is somewhat erratic, with a slow oscillation about the long axis.Trypanosoma brucei gambiense: A hemoflagellate subspecies of parasitic protozoa that causes Gambian or West African sleeping sickness in humans. The vector host is usually the tsetse fly (Glossina).Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Bacterial Proteins: Proteins found in any species of bacterium.Trypanosomiasis, African: A disease endemic among people and animals in Central Africa. It is caused by various species of trypanosomes, particularly T. gambiense and T. rhodesiense. Its second host is the TSETSE FLY. Involvement of the central nervous system produces "African sleeping sickness." Nagana is a rapidly fatal trypanosomiasis of horses and other animals.Giardiasis: An infection of the SMALL INTESTINE caused by the flagellated protozoan GIARDIA LAMBLIA. It is spread via contaminated food and water and by direct person-to-person contact.Relapsing Fever: An acute infection characterized by recurrent episodes of PYREXIA alternating with asymptomatic intervals of apparent recovery. This condition is caused by SPIROCHETES of the genus BORRELIA. It is transmitted by the BITES of either the body louse (PEDICULUS humanus corporis), for which humans are the reservoir, or by soft ticks of the genus ORNITHODOROS, for which rodents and other animals are the principal reservoirs.Immune Evasion: Methods used by pathogenic organisms to evade a host's immune system.Antigens, Surface: Antigens on surfaces of cells, including infectious or foreign cells or viruses. They are usually protein-containing groups on cell membranes or walls and may be isolated.Anaplasma: A genus of gram-negative bacteria whose organisms are obligate parasites of vertebrates. Species are transmitted by arthropod vectors with the host range limited to ruminants. Anaplasma marginale is the most pathogenic species and is the causative agent of severe bovine anaplasmosis.Genome, Protozoan: The complete genetic complement contained in a set of CHROMOSOMES in a protozoan.RNA, Protozoan: Ribonucleic acid in protozoa having regulatory and catalytic roles as well as involvement in protein synthesis.DNA, Protozoan: Deoxyribonucleic acid that makes up the genetic material of protozoa.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Cross Reactions: Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.Campylobacter fetus: A species of bacteria present in man and many kinds of animals and birds, often causing infertility and/or abortion.Neutralization Tests: The measurement of infection-blocking titer of ANTISERA by testing a series of dilutions for a given virus-antiserum interaction end-point, which is generally the dilution at which tissue cultures inoculated with the serum-virus mixtures demonstrate cytopathology (CPE) or the dilution at which 50% of test animals injected with serum-virus mixtures show infectivity (ID50) or die (LD50).Serotyping: Process of determining and distinguishing species of bacteria or viruses based on antigens they share.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Gene Conversion: The asymmetrical segregation of genes during replication which leads to the production of non-reciprocal recombinant strands and the apparent conversion of one allele into another. Thus, e.g., the meiotic products of an Aa individual may be AAAa or aaaA instead of AAaa, i.e., the A allele has been converted into the a allele or vice versa.Aphthovirus: A genus of the family PICORNAVIRIDAE infecting mainly cloven-hoofed animals. They cause vesicular lesions and upper respiratory tract infections. FOOT AND MOUTH DISEASE VIRUS is the type species.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Multigene Family: A set of genes descended by duplication and variation from some ancestral gene. Such genes may be clustered together on the same chromosome or dispersed on different chromosomes. Examples of multigene families include those that encode the hemoglobins, immunoglobulins, histocompatibility antigens, actins, tubulins, keratins, collagens, heat shock proteins, salivary glue proteins, chorion proteins, cuticle proteins, yolk proteins, and phaseolins, as well as histones, ribosomal RNA, and transfer RNA genes. The latter three are examples of reiterated genes, where hundreds of identical genes are present in a tandem array. (King & Stanfield, A Dictionary of Genetics, 4th ed)Malaria, Falciparum: Malaria caused by PLASMODIUM FALCIPARUM. This is the severest form of malaria and is associated with the highest levels of parasites in the blood. This disease is characterized by irregularly recurring febrile paroxysms that in extreme cases occur with acute cerebral, renal, or gastrointestinal manifestations.Fimbriae, Bacterial: Thin, hairlike appendages, 1 to 20 microns in length and often occurring in large numbers, present on the cells of gram-negative bacteria, particularly Enterobacteriaceae and Neisseria. Unlike flagella, they do not possess motility, but being protein (pilin) in nature, they possess antigenic and hemagglutinating properties. They are of medical importance because some fimbriae mediate the attachment of bacteria to cells via adhesins (ADHESINS, BACTERIAL). Bacterial fimbriae refer to common pili, to be distinguished from the preferred use of "pili", which is confined to sex pili (PILI, SEX).Telomere: A terminal section of a chromosome which has a specialized structure and which is involved in chromosomal replication and stability. Its length is believed to be a few hundred base pairs.Hemagglutination Inhibition Tests: Serologic tests in which a known quantity of antigen is added to the serum prior to the addition of a red cell suspension. Reaction result is expressed as the smallest amount of antigen which causes complete inhibition of hemagglutination.Mycoplasma: A genus of gram-negative, mostly facultatively anaerobic bacteria in the family MYCOPLASMATACEAE. The cells are bounded by a PLASMA MEMBRANE and lack a true CELL WALL. Its organisms are pathogens found on the MUCOUS MEMBRANES of humans, ANIMALS, and BIRDS.Equine Infectious Anemia: Viral disease of horses caused by the equine infectious anemia virus (EIAV; INFECTIOUS ANEMIA VIRUS, EQUINE). It is characterized by intermittent fever, weakness, and anemia. Chronic infection consists of acute episodes with remissions.Orthomyxoviridae: A family of RNA viruses causing INFLUENZA and other diseases. There are five recognized genera: INFLUENZAVIRUS A; INFLUENZAVIRUS B; INFLUENZAVIRUS C; ISAVIRUS; and THOGOTOVIRUS.Antibodies, Bacterial: Immunoglobulins produced in a response to BACTERIAL ANTIGENS.Lipoproteins: Lipid-protein complexes involved in the transportation and metabolism of lipids in the body. They are spherical particles consisting of a hydrophobic core of TRIGLYCERIDES and CHOLESTEROL ESTERS surrounded by a layer of hydrophilic free CHOLESTEROL; PHOSPHOLIPIDS; and APOLIPOPROTEINS. Lipoproteins are classified by their varying buoyant density and sizes.Lyme Disease: An infectious disease caused by a spirochete, BORRELIA BURGDORFERI, which is transmitted chiefly by Ixodes dammini (see IXODES) and pacificus ticks in the United States and Ixodes ricinis (see IXODES) in Europe. It is a disease with early and late cutaneous manifestations plus involvement of the nervous system, heart, eye, and joints in variable combinations. The disease was formerly known as Lyme arthritis and first discovered at Old Lyme, Connecticut.Borrelia burgdorferi: A specific species of bacteria, part of the BORRELIA BURGDORFERI GROUP, whose common name is Lyme disease spirochete.Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.Genes, Bacterial: The functional hereditary units of BACTERIA.Gene Silencing: Interruption or suppression of the expression of a gene at transcriptional or translational levels.Agglutination Tests: Tests that are dependent on the clumping of cells, microorganisms, or particles when mixed with specific antiserum. (From Stedman, 26th ed)Repetitive Sequences, Nucleic Acid: Sequences of DNA or RNA that occur in multiple copies. There are several types: INTERSPERSED REPETITIVE SEQUENCES are copies of transposable elements (DNA TRANSPOSABLE ELEMENTS or RETROELEMENTS) dispersed throughout the genome. TERMINAL REPEAT SEQUENCES flank both ends of another sequence, for example, the long terminal repeats (LTRs) on RETROVIRUSES. Variations may be direct repeats, those occurring in the same direction, or inverted repeats, those opposite to each other in direction. TANDEM REPEAT SEQUENCES are copies which lie adjacent to each other, direct or inverted (INVERTED REPEAT SEQUENCES).Mycoplasma genitalium: A species of gram-negative bacteria originally isolated from urethral specimens of patients with non-gonoccocal URETHRITIS. In primates it exists in parasitic association with ciliated EPITHELIAL CELLS in the genital and respiratory tracts.Hemagglutinins, Viral: Specific hemagglutinin subtypes encoded by VIRUSES.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Immune Sera: Serum that contains antibodies. It is obtained from an animal that has been immunized either by ANTIGEN injection or infection with microorganisms containing the antigen.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Immunodominant Epitopes: Subunits of the antigenic determinant that are most easily recognized by the immune system and thus most influence the specificity of the induced antibody.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Influenza A virus: The type species of the genus INFLUENZAVIRUS A that causes influenza and other diseases in humans and animals. Antigenic variation occurs frequently between strains, allowing classification into subtypes and variants. Transmission is usually by aerosol (human and most non-aquatic hosts) or waterborne (ducks). Infected birds shed the virus in their saliva, nasal secretions, and feces.Antibodies, Protozoan: Immunoglobulins produced in a response to PROTOZOAN ANTIGENS.Spirochaetales: An order of slender, flexuous, helically coiled bacteria, with one or more complete turns in the helix.Giardia: A genus of flagellate intestinal EUKARYOTES parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Radioimmunoprecipitation Assay: Sensitive assay using radiolabeled ANTIGENS to detect specific ANTIBODIES in SERUM. The antigens are allowed to react with the serum and then precipitated using a special reagent such as PROTEIN A sepharose beads. The bound radiolabeled immunoprecipitate is then commonly analyzed by gel electrophoresis.Plasmodium: A genus of protozoa that comprise the malaria parasites of mammals. Four species infect humans (although occasional infections with primate malarias may occur). These are PLASMODIUM FALCIPARUM; PLASMODIUM MALARIAE; PLASMODIUM OVALE, and PLASMODIUM VIVAX. Species causing infection in vertebrates other than man include: PLASMODIUM BERGHEI; PLASMODIUM CHABAUDI; P. vinckei, and PLASMODIUM YOELII in rodents; P. brasilianum, PLASMODIUM CYNOMOLGI; and PLASMODIUM KNOWLESI in monkeys; and PLASMODIUM GALLINACEUM in chickens.Anaplasma marginale: A species of gram-negative bacteria and causative agent of severe bovine ANAPLASMOSIS. It is the most pathogenic of the ANAPLASMA species.Anaplasmosis: A disease of cattle caused by parasitization of the red blood cells by bacteria of the genus ANAPLASMA.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.Antigens: Substances that are recognized by the immune system and induce an immune reaction.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.Anaplasma phagocytophilum: A species of gram-negative bacteria in the genus ANAPLASMA, family ANAPLASMATACEAE, formerly called Ehrlichia phagocytophila or Ehrlichia equi. This organism is tick-borne (IXODES) and causes disease in horses and sheep. In humans, it causes human granulocytic EHRLICHIOSIS.Infectious Anemia Virus, Equine: A species of LENTIVIRUS, subgenus equine lentiviruses (LENTIVIRUSES, EQUINE), causing acute and chronic infection in horses. It is transmitted mechanically by biting flies, mosquitoes, and midges, and iatrogenically through unsterilized equipment. Chronic infection often consists of acute episodes with remissions.Immunogenetics: A subdiscipline of genetics which deals with the genetic basis of the immune response (IMMUNITY).Virulence: The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Neisseria meningitidis: A species of gram-negative, aerobic BACTERIA. It is a commensal and pathogen only of humans, and can be carried asymptomatically in the NASOPHARYNX. When found in cerebrospinal fluid it is the causative agent of cerebrospinal meningitis (MENINGITIS, MENINGOCOCCAL). It is also found in venereal discharges and blood. There are at least 13 serogroups based on antigenic differences in the capsular polysaccharides; the ones causing most meningitis infections being A, B, C, Y, and W-135. Each serogroup can be further classified by serotype, serosubtype, and immunotype.Rec A Recombinases: A family of recombinases initially identified in BACTERIA. They catalyze the ATP-driven exchange of DNA strands in GENETIC RECOMBINATION. The product of the reaction consists of a duplex and a displaced single-stranded loop, which has the shape of the letter D and is therefore called a D-loop structure.Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.Chromosomes: In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Antibody Specificity: The property of antibodies which enables them to react with some ANTIGENIC DETERMINANTS and not with others. Specificity is dependent on chemical composition, physical forces, and molecular structure at the binding site.Epitope Mapping: Methods used for studying the interactions of antibodies with specific regions of protein antigens. Important applications of epitope mapping are found within the area of immunochemistry.Adhesins, Bacterial: Cell-surface components or appendages of bacteria that facilitate adhesion (BACTERIAL ADHESION) to other cells or to inanimate surfaces. Most fimbriae (FIMBRIAE, BACTERIAL) of gram-negative bacteria function as adhesins, but in many cases it is a minor subunit protein at the tip of the fimbriae that is the actual adhesin. In gram-positive bacteria, a protein or polysaccharide surface layer serves as the specific adhesin. What is sometimes called polymeric adhesin (BIOFILMS) is distinct from protein adhesin.Transcription, Genetic: The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.Sequence Homology, Nucleic Acid: The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.Mycoplasma Infections: Infections with species of the genus MYCOPLASMA.Selection, Genetic: Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.Conserved Sequence: A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences.Eukaryota: One of the three domains of life (the others being BACTERIA and ARCHAEA), also called Eukarya. These are organisms whose cells are enclosed in membranes and possess a nucleus. They comprise almost all multicellular and many unicellular organisms, and are traditionally divided into groups (sometimes called kingdoms) including ANIMALS; PLANTS; FUNGI; and various algae and other taxa that were previously part of the old kingdom Protista.Genome, Bacterial: The genetic complement of a BACTERIA as represented in its DNA.Horses: Large, hoofed mammals of the family EQUIDAE. Horses are active day and night with most of the day spent seeking and consuming food. Feeding peaks occur in the early morning and late afternoon, and there are several daily periods of rest.Enzyme-Linked Immunosorbent Assay: An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Disease Vectors: Invertebrates or non-human vertebrates which transmit infective organisms from one host to another.Borrelia burgdorferi Group: Gram-negative helical bacteria, in the genus BORRELIA, that are the etiologic agents of LYME DISEASE. The group comprises many specific species including Borrelia afzelii, Borellia garinii, and BORRELIA BURGDORFERI proper. These spirochetes are generally transmitted by several species of ixodid ticks.Sequence Homology: The degree of similarity between sequences. Studies of AMINO ACID SEQUENCE HOMOLOGY and NUCLEIC ACID SEQUENCE HOMOLOGY provide useful information about the genetic relatedness of genes, gene products, and species.Ticks: Blood-sucking acarid parasites of the order Ixodida comprising two families: the softbacked ticks (ARGASIDAE) and hardbacked ticks (IXODIDAE). Ticks are larger than their relatives, the MITES. They penetrate the skin of their host by means of highly specialized, hooked mouth parts and feed on its blood. Ticks attack all groups of terrestrial vertebrates. In humans they are responsible for many TICK-BORNE DISEASES, including the transmission of ROCKY MOUNTAIN SPOTTED FEVER; TULAREMIA; BABESIOSIS; AFRICAN SWINE FEVER; and RELAPSING FEVER. (From Barnes, Invertebrate Zoology, 5th ed, pp543-44)Cattle Diseases: Diseases of domestic cattle of the genus Bos. It includes diseases of cows, yaks, and zebus.Neuraminidase: An enzyme that catalyzes the hydrolysis of alpha-2,3, alpha-2,6-, and alpha-2,8-glycosidic linkages (at a decreasing rate, respectively) of terminal sialic residues in oligosaccharides, glycoproteins, glycolipids, colominic acid, and synthetic substrate. (From Enzyme Nomenclature, 1992)Viral Envelope Proteins: Layers of protein which surround the capsid in animal viruses with tubular nucleocapsids. The envelope consists of an inner layer of lipids and virus specified proteins also called membrane or matrix proteins. The outer layer consists of one or more types of morphological subunits called peplomers which project from the viral envelope; this layer always consists of glycoproteins.

Genetic and antigenic variation of capsid protein VP7 of serotype G1 human rotavirus isolates. (1/863)

The deduced amino acid sequences of the outer capsid protein, VP7, of serotype G1 rotavirus clinical isolates collected over a 6 year period (1990-1995) in Melbourne, Australia, were examined. Phylogenetic analysis characterized the sequences into two discrete clusters representing two of the four global lineages of human G1 VP7 proteins. Antigenic characterization using a panel of serotype G1-specific neutralizing monoclonal antibodies classified lineage II isolates (1990-1993) as monotype G1a while lineage I isolates were classified as monotype G1b (1993-1995). Examination of the sequences of the neutralization epitope regions of VP7 revealed a particular amino acid substitution at residue 94 in region A (Asp --> Ser/Thr) that correlated with lineage and monotype designation. Our results indicated that temporal genetic variation of the VP7 of serotype G1 rotaviruses was associated with changes in the antigenicity of these isolates.  (+info)

The major immunogenic epitopes of Epstein-Barr virus (EBV) nuclear antigen 1 are encoded by sequence domains which vary among nasopharyngeal carcinoma biopsies and EBV-associated cell lines. (2/863)

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) is a protein expressed consistently in EBV-infected cells and EBV-associated malignant tissues. A panel of monoclonal antibodies (MAbs) was generated against the C terminus of EBNA-1 and evaluated for the detection of EBNA-1 in different cell lines. The epitopes recognized were mapped. Since sequence variations of EBNA-1 have been reported in nasopharyngeal carcinoma (NPC) tissues and in infected healthy individuals, the ability of these MAbs to recognize a recombinant protein derived from an NPC biopsy was also analysed. MAb 4H11 appeared to react with EBNA-1 sequences from different sources, whereas MAbs 5C11, 5F12 and 8F6 failed to recognize a recombinant EBNA-1 protein cloned from an NPC patient. Using different recombinant EBNA-1 fragments in an immunoblot format, this study demonstrates that the domain bounded by amino acids 408 and 498 is very immunogenic in mice in that epitopes in this region are recognized by various MAbs. Amino acid sequences of EBNA-1 were also deduced from nucleotide sequences amplified from three Burkitt's lymphoma cell lines, two spontaneous lymphoblastoid cell lines, two NPC biopsies and one NPC hybrid cell line, NPC-KT, and compared to the sequence from B95-8. The amino acid sequence of EBNA-1 in Akata is almost identical to that in an NPC biopsy, except for amino acid 585. The results of this study indicate that the immunogenic epitopes of EBNA-1 are highly variable.  (+info)

Antigenic variation in malaria: a 3' genomic alteration associated with the expression of a P. knowlesi variant antigen. (3/863)

Antigenic variation of malaria parasites was discovered in P. knowlesi, using a schizont-infected cell agglutination (SICA) assay to detect variant antigens expressed at the surface of infected erythrocytes. Later studies utilizing stable clones, Pk1(A+) and its direct derivative, Pk1(B+)1+, showed that SICA[+] clones express distinct parasite-encoded antigens of approximately 200 kDa. Here we identify a P. knowlesi variant antigen gene and cDNA and demonstrate that it encodes the 205 kDa variant antigen expressed by B+ parasites. This gene belongs to a multigene family, which we term SICAvar. Its ten-exon structure with seven cysteine-rich coding modules is unique compared to P. falciparum var genes. Further, we highlight a 3' genomic alteration that we predict is related to SICAvar gene switching.  (+info)

Phase variations of the Mycoplasma penetrans main surface lipoprotein increase antigenic diversity. (4/863)

Mycoplasma penetrans is a recently identified mycoplasma, isolated from urine samples collected from human immunodeficiency virus (HIV)-infected patients. Its presence is significantly associated with HIV infection. The major antigen recognized during natural and experimental infections is an abundant P35 lipoprotein which, upon extraction, segregates in the Triton X-114 detergent phase and is the basis of M. penetrans-specific serological assays. We report here that the P35 antigen undergoes spontaneous and reversible phase variation at high frequency, leading to heterogeneous populations of mycoplasmas, even when derived from a clonal lineage. This variation was found to be determined at the transcription level, and although this property is not unique among the members of the class Mollicutes, the mechanism by which it occurs in M. penetrans differs from those previously described for other Mycoplasma species. Indeed, the P35 phase variation was due neither to a p35 gene rearrangement nor to point mutations within the gene itself or its promoter. The P35 phase variation in the different variants obtained was concomitant with modifications in the pattern of other expressed lipoproteins, probably due to regulated expression of selected members of a gene family which was found to potentially encode similar lipoproteins. M. penetrans variants could be selected on the basis of their lack of colony immunoreactivity with a polyclonal antiserum against a Triton X-114 extract, strongly suggesting that the mechanisms involved in altering surface antigen expression might allow evasion of the humoral immune response of the infected host.  (+info)

Molecular and functional analysis of a conserved CTL epitope in HIV-1 p24 recognized from a long-term nonprogressor: constraints on immune escape associated with targeting a sequence essential for viral replication. (5/863)

It has been hypothesized that sequence variation within CTL epitopes leading to immune escape plays a role in the progression of HIV-1 infection. Only very limited data exist that address the influence of biologic characteristics of CTL epitopes on the emergence of immune escape variants and the efficiency of suppression HIV-1 by CTL. In this report, we studied the effects of HIV-1 CTL epitope sequence variation on HIV-1 replication. The highly conserved HLA-B14-restricted CTL epitope DRFYKTLRAE in HIV-1 p24 was examined, which had been defined as the immunodominant CTL epitope in a long-term nonprogressing individual. We generated a set of viral mutants on an HX10 background differing by a single conservative or nonconservative amino acid substitution at each of the P1 to P9 amino acid residues of the epitope. All of the nonconservative amino acid substitutions abolished viral infectivity and only 5 of 10 conservative changes yielded replication-competent virus. Recognition of these epitope sequence variants by CTL was tested using synthetic peptides. All mutations that abrogated CTL recognition strongly impaired viral replication, and all replication-competent viral variants were recognized by CTL, although some variants with a lower efficiency. Our data indicate that this CTL epitope is located within a viral sequence essential for viral replication. Targeting CTL epitopes within functionally important regions of the HIV-1 genome could limit the chance of immune evasion.  (+info)

Spontaneous regression of primary autoreactivity during chronic progression of experimental autoimmune encephalomyelitis and multiple sclerosis. (6/863)

Experimental autoimmune encephalomyelitis (EAE) is a widely used animal model for multiple sclerosis (MS). EAE is typically initiated by CD4(+) T helper cell type 1 (Th1) autoreactivity directed against a single priming immunodominant myelin peptide determinant. Recent studies have shown that clinical progression of EAE involves the accumulation of neo-autoreactivity, commonly referred to as epitope spreading, directed against peptide determinants not involved in the priming process. This study directly addresses the relative roles of primary autoreactivity and secondary epitope spreading in the progression of both EAE and MS. To this end we serially evaluated the development of several epitope-spreading cascades in SWXJ mice primed with distinctly different encephalitogenic determinants of myelin proteolipid protein. In a series of analogous experiments, we examined the development of epitope spreading in patients with isolated monosymptomatic demyelinating syndrome as their disease progressed to clinically definite MS. Our results indicate that in both EAE and MS, primary proliferative autoreactivity associated with onset of clinical disease invariably regresses with time and is often undetectable during periods of disease progression. In contrast, the emergence of sustained secondary autoreactivity to spreading determinants is consistently associated with disease progression in both EAE and MS. Our results indicate that chronic progression of EAE and MS involves a shifting of autoreactivity from primary initiating self-determinants to defined cascades of secondary determinants that sustain the self-recognition process during disease progression.  (+info)

Antigenic heterogeneity of the hepatitis C virus NS4 protein as modeled with synthetic peptides. (7/863)

The effect of sequence heterogeneity on the immunologic properties of two strong antigenic regions of the hepatitis C virus (HCV) NS4 protein was studied by using a set of 443 overlapping 20-mer synthetic peptides. One antigenic region comprising the cleavage site between NS4a and NS4b (region 5-1-1) was modeled with peptides derived from 73 different known sequences, representing HCV genotypes 1-6. The other antigenic region, designated region 59 and located at the C-terminus of the NS4b protein, was modeled with peptides from 7 known sequences representing genotypes 1-3. All peptides were tested for antigenic reactivity by enzyme immunoassay with a panel of anti-HCV-positive serum specimens representing genotypes 1-5. The data demonstrated that immunoreactive peptides fell into two groups. One group, represented by N-terminal peptides, demonstrated genotype-independent immunoreactivity; the other group, from the central part of region 5-1-1, showed strict genotype specificity. Nineteen peptides from the genotype-independent group strongly immunoreacted with a wide range of serum samples containing antibodies to all 5 HCV genotypes. Twenty-five peptides from the genotype-specific group were found to strongly react with serum containing antibodies only to the genotype from which the peptides were derived. Similar to the N-terminal part of region 5-1-1, peptides derived from region 59 did not show genotype-specific immunoreactivity. Some peptides derived from the central part of region 59 showed very strong and broad antigenic reactivity. Thus, after examining two antigenic regions of the NS4 protein, we identified short sequences that can be used for the efficient detection of either genotype-independent or genotype-specific HCV antibodies.  (+info)

Structural and evolutionary inference from molecular variation in Neisseria porins. (8/863)

The porin proteins of the pathogenic Neisseria species, Neisseria gonorrhoeae and Neisseria meningitidis, are important as serotyping antigens, putative vaccine components, and for their proposed role in the intracellular colonization of humans. A three-dimensional structural homology model for Neisseria porins was generated from Escherichia coli porin structures and N. meningitidis PorA and PorB sequences. The Neisseria sequences were readily assembled into the 16-strand beta-barrel fold characteristic of porins, despite relatively low sequence identity with the Escherichia proteins. The model provided information on the spatial relationships of variable regions of peptide sequences in the PorA and PorB trimers and insights relevant to the use of these proteins in vaccines. The nucleotide sequences of the porin genes from a number of other Neisseria species were obtained by PCR direct sequencing and from GenBank. Alignment and analysis of all available Neisseria porin sequences by use of the structurally conserved regions derived from the PorA and PorB structural models resulted in the recovery of an improved phylogenetic signal. Phylogenetic analyses were consistent with an important role for horizontal genetic exchange in the emergence of different porin classes and confirmed the close evolutionary relationships of the porins from N. meningitidis, N. gonorrhoeae, Neisseria lactamica, and Neisseria polysaccharea. Only members of this group contained three conserved lysine residues which form a potential GTP binding site implicated in pathogenesis. The model placed these residues on the inside of the pore, in close proximity, consistent with their role in regulating pore function when inserted into host cells.  (+info)

*Plasmodium falciparum erythrocyte membrane protein 1

Kyes, S. A.; Kraemer, S. M.; Smith, J. D. (2007). "Antigenic variation in Plasmodium falciparum: Gene organization and ... Scherf, Artur; Lopez-Rubio, Jose Juan; Riviere, Loïc (2008). "Antigenic variation in Plasmodium falciparum". Annual Review of ... "The large diverse gene family var encodes proteins involved in cytoadherence and antigenic variation of Plasmodium falciparum- ... This variation gives rise to different types of PfEMP1. The DBL-CIDR combination in a particular type of PfEMP1 protein is ...

*Antigenic variation

shows that some DNA viruses have the same high rates of antigenic variation as their RNA counterparts. Antigenic variation ... Antigenic variation may be classified into two types, antigenic drift that results from a change in few amino acids and ... In all cases, antigenic variation and phase variation result in a heterogenic phenotype of a clonal population. Individual ... Antigenic variation refers to the mechanism by which an infectious agent such as a protozoan, bacterium or virus alters its ...

*Immune system

This is called antigenic variation. An example is HIV, which mutates rapidly, so the proteins on its viral envelope that are ... The B cell then displays these antigenic peptides on its surface MHC class II molecules. This combination of MHC and antigen ... Welling GW, Weijer WJ, van der Zee R, Welling-Wester S (Sep 1985). "Prediction of sequential antigenic regions in proteins". ... immune system using Grid technologies Immunoproteomics Immunostimulator Original antigenic sin Plant disease resistance ...

*José Esparza

Antigenic variation of Latinamerican rotavirus. Structural studies of the rotavirus inner capsid. Gene sequence of some ... Puerto Manzano, F; Avendano, L; Esparza, J; Caul, EO (Dec 1984). "Antigenic variation in Latin American human pararotaviruses ( ...

*Variant surface glycoprotein

Barry JD, McCulloch R (2001). "Antigenic variation in trypanosomes: enhanced phenotypic variation in a eukaryotic parasite". ... Periodic antigenic variation - the VSG coat undergoes frequent stochastic genetic modification-'switching'-allowing variants ... This antigenic variation creates cyclical waves of parasitemia characteristic of Human African Trypanosomiasis. Antigen ' ... VSG allows the trypanosomatid parasites to evade the mammalian host's immune system by extensive antigenic variation. VSG has ...

*Phase variation

van der Woude MW, Bäumler AJ (2004). "Phase and antigenic variation in bacteria". Clin Microbiol Rev. 17 (3): 581-611. doi: ... Wisniewski-Dyé F, Vial L (2008). "Phase and antigenic variation mediated by genome modifications". Antonie Van Leeuwenhoek. 94 ... It involves the variation of protein expression, frequently in an on-off fashion, within different parts of a bacterial ... In this form of phase variation. The promoter region of the genome can move from one copy of a gene to another through ...

*Relapsing fever

Important questions about antigenic variation are also relevant for such research areas as developing a vaccine against HIV and ... Antigenic variation is common among pathogenic organisms. These include the agents of malaria, gonorrhea, and sleeping sickness ... through antigenic variation. Essentially, the pathogen stays one step ahead of antibodies by changing its surface proteins. ... which is sufficient to create a new antigenic "identity" for the organism. Antibodies in the blood that are binding to and ...

*Russell J. Howard

Thirteen years of his group's malaria research on antigenic variation in malaria culminated in the first molecular cloning of ... Antigenic variation in Plasmodium knowlesi malaria: Identification of the variant antigen on infected erythrocytes. Proc. Natl ... to the molecular pathogenesis of human cerebral malaria and the role of parasite antigenic variation and infected cell ... Howard, R.J.: Antigenic variation of blood stage malaria parasites. Phil. Trans. R. Soc. Lond. B 307: 141-158, 1984. • http:// ...

*Cassava mosaic virus

Harrison B & Robinson D (1999). Natural genomic and antigenic variation in whitefly-transmitted geminiviruses (begomoviruses). ... There is variation in the literature on this score, however, with other sources citing a 4-hour acquisition time and 4-hour ... Little to no infection occurs after three months, and variation in spread was due to change in temperature, radiation and ...

*Neisseria gonorrhoeae

All are antigenic and all exhibit antigenic variation (see below). The pili exhibit the most variation. The pili, Opa proteins ... N. gonorrhoeae evades the immune system through a process called antigenic variation, in which the N. gonorrhoeae bacterium is ... Development of a vaccine has been complicated by the ongoing evolution of resistant strains and antigenic variation (the ... Cahoon, Laty A.; Seifert, H. Steven (2011). "Focusing homologous recombination: Pilin antigenic variation in the pathogenic ...

*Trypanosomatida

Morrison LJ, Marcello L, McCulloch R; Marcello; McCulloch (December 2009). "Antigenic variation in the African trypanosome: ...

*Sunetra Gupta

"Transient cross-reactive immune responses can orchestrate antigenic variation in malaria". Nature. 429 (6991): 555-558. doi: ... "The generation of influenza outbreaks by a network of host immune responses against a limited set of antigenic types". ...

*Giardia lamblia

2008). "Antigenic variation in Giardia lamblia is regulated by RNA interference". Nature. 456 (7223): 750-4. doi:10.1038/ ... called antigenic variation). Gillin's work reveals why Giardia infections are extremely persistent and prone to recur. In ... Svärd SG, Meng TC, Hetsko ML, McCaffery JM, Gillin FD (1998). "Differentiation-associated surface antigen variation in the ...

*William A. Haseltine

Clements, JE; Pedersen FS; Narayan O; Haseltine WA (1980). "Genomic Changes Associated with Antigenic Variation of Visna Virus ... Terwilliger, EF; Langhoff E; Gabuzda D; Haseltine W; Haseltine, W. A. (1991). "Allelic variation in the effects of nef on HIV-1 ...

*Viral evolution

Barrett, p. 24 Chen J, Deng YM (2009). "Influenza virus antigenic variation, host antibody production and new approach to ...

*Piet Borst

A DNA transposition mechanism for antigenic variation in African trypanosomes (9) (10) (11) (12). Transsplicing as an essential ... Bitter W, Gerrits H, Kieft R, Borst P. The role of transferrin-receptor variation in the host range of Trypanosoma brucei. ... J, a new base in the DNA of trypanosomes and related parasites (30) (31). Variation in the transferrin receptor allows African ...

*Immunodominance

Similar to HIV-escape, cancer can escape the immune system's detection by antigenic variation. As the immunodominant epitope is ... Immunodominance is the immunological phenomenon in which immune responses are mounted against only a few of the antigenic ... That is, despite multiple allelic variations of MHC molecules and multiple peptides presented on antigen presenting cells, the ...

*Antigenic escape

Its most prevalent mechanism is its ability to evade recognition by antibodies through antigenic variation. This is achieved ... One cause of antigenic escape is that a pathogen's epitopes (the binding sites for immune cells) become too similar to a ... However, variation of this coat can lead to antibodies being unable to recognize and clear the antigen. In addition to this, ... Antigenic escape occurs when the immune system is unable to respond to an infectious agent. This means that the response ...

*Borrelia hermsii

Dai Q, Restrepo BI, Porcella SF, Raffel SJ, Schwan TG, Barbour AG (June 2006). "Antigenic variation by Borrelia hermsii occurs ...

*Viral phylodynamics

Genetic and antigenic variation of influenza is also present across a diverse set of host species. The impact of host ... These antigenic dynamics would be consistent with a ladder-like phylogeny of influenza exhibiting low genetic diversity and ... In recent work, Bedford and colleagues used an agent-based model to show that evolution in a Euclidean antigenic space can ... Fraser, C.; Hollingsworth, T. D.; Chapman, R.; De Wolf, F.; Hanage, W. P. (2007). "Variation in HIV-1 set-point viral load: ...

*Orientia tsutsugamushi

Enormous antigenic variation in Orientia tsutsugamushi strains is now known, and immunity to one strain does not confer ... A vaccine developed for one locality may not be protective in another locality, because of antigenic variation. This complexity ... Kang JS, Chang WH (1999). "Antigenic relationship among the eight prototype and new serotype strains of Orientia tsutsugamushi ...

*Eimeria

However, the search for highly immunogenic antigens and overcoming antigenic variation of the parasites remains a challenge. ... CS1 maint: Uses authors parameter (link) Shirley MW (1975). "Enzyme variation in Eimeria species of the chicken". Parasitology ...

*Trypanosoma

These trypanosomes are passed to the recipient in the saliva of the tsetse fly (Glossina spp.). Antigenic variation is a ...

*Mosaic (genetics)

The term "somatic mosaicism" was used by C. W. Cotterman in 1956 in his seminal paper on antigenic variation. Chimera (genetics ...

*Borrelia mayonii

Norris, Steven J. (2014-12-01). "vls Antigenic Variation Systems of Lyme Disease Borrelia: Eluding Host Immunity through both ... Zhang, Jing-Ren; Norris, Steven J. (1998-08-01). "Genetic Variation of the Borrelia burgdorferi Gene vlsE Involves Cassette- ... "Variations in Barbour-Stoenner-Kelly Culture Medium Modulate Infectivity and Pathogenicity of Borrelia burgdorferi Clinical ...

*Lyme disease

... antigenic variation of the VlsE surface protein, inactivating key immune components such as complement, and hiding in the ... Is it a new tick borne disease or Lyme disease variation?". Braz. J. Med. Biol. Res. 40 (4): 443-56. doi:10.1590/S0100- ...
Looking for antigenic variation? Find out information about antigenic variation. Alteration of an antigen on the surface of a microorganism; may enable a pathogenic mocroorganism to evade destruction by the hosts immune system Explanation of antigenic variation
Different virus families have different levels of ability to alter their genomes and trick the immune system into not recognizing. Some viruses have relatively unchanging genomes like paramyxoviruses while others like influenza have rapidly changing genomes that inhibit our ability to create long lasting vaccines against the disease. Viruses in general have much faster rate of mutation of their genomes than human or bacterial cells. In general viruses with shorter genomes have faster rates of mutation than longer genomes since they have a faster rate of replication.[15] It was classically thought that viruses with an RNA genome always had a faster rate of antigenic variation than those with a DNA genome because RNA polymerase lacks a mechanism for checking for mistakes in translation but recent work by Duffy et al. shows that some DNA viruses have the same high rates of antigenic variation as their RNA counterparts.[15] Antigenic variation within viruses can be categories into 6 different ...
An antigenic shift generally refers to the medical term that explains how two strains of the influenza virus join together to form a new subtype and, in turn, become more virile. The new subtype has a mixture of the antigens from the originals. An antigen is the substance that stimulates the immune system. [3] Its used here to refer to rumors about severe weather and the Quebec Junior Team. These rumors undergo an antigenic shift as they circulate around the locker room. They combine and are reconstituted as a new, more virile, rumor before being returned to the rumors originator ...
An antigenic shift generally refers to the medical term that explains how two strains of the influenza virus join together to form a new subtype and, in turn, become more virile. The new subtype has a mixture of the antigens from the originals. An antigen is the substance that stimulates the immune system. [3] Its used here to refer to rumors about severe weather and the Quebec Junior Team. These rumors undergo an antigenic shift as they circulate around the locker room. They combine and are reconstituted as a new, more virile, rumor before being returned to the rumors originator ...
Many evolutionarily distant pathogenic organisms have evolved similar survival strategies to evade the immune responses of their hosts. These include antigenic variation, through which an infecting organism prevents clearance by periodically altering the identity of proteins that are visible to the immune system of the host1. Antigenic variation requires large reservoirs of immunologically diverse antigen genes, which are often generated through homologous recombination, as well as mechanisms to ensure the expression of one or very few antigens at any given time. Both homologous recombination and gene expression are affected by three-dimensional genome architecture and local DNA accessibility2,3. Factors that link three-dimensional genome architecture, local chromatin conformation and antigenic variation have, to our knowledge, not yet been identified in any organism. One of the major obstacles to studying the role of genome architecture in antigenic variation has been the highly repetitive ...
A simple predictive model estimates the fitness $f$ of virus $i$ as. $$\hat{f}_i = \beta^\mathrm{ep} \, f_i^\mathrm{ep} + \beta^\mathrm{ne} \, f_i^\mathrm{ne}$$. where $f_i^\mathrm{ep}$ measures cross-immunity via substitutions at epitope sites and $f_i^\mathrm{ep}$ measures mutational load via substitutions at non-epitope sites.. ...
Principal Investigator:FUKUMA Toshihide, Project Period (FY):1992 - 1993, Research Category:Grant-in-Aid for General Scientific Research (C), Research Field:寄生虫学(含医用動物学)
Influenza A viruses circulate in humans, birds, and pigs. Occasionally, different influenza A viruses can infect a single host at the same time. This often happens in places where humans and animals live in close contact. The genetic material of the viruses gets mixed up, creating an entirely new virus. (This process is called antigenic shift or viral reassortment.) If the new virus makes people sick and is transmitted easily from person to person, an influenza pandemic can occur.. Thats what happened in the spring of 2009: the virus thats making the news right now has genes from flu viruses that normally circulate in pigs in Europe and Asia as well as avian (bird) and human genes.. ...
More Influenza Essay Topics.. In that year, H2N2 viruses circulated, followed by H3N8 in 1900, H1N1 in 1918, H2N2 in 1957, H3N2 in 1968, and H1N1 in 1977," with the latest antigenic shift being in 2009 with the H1N1 virus. This shows the emergence of the H1N1 strain of the virus was in 1918. The reason that these were major pandemics back then was because of the lack of treatments. The virus was unchecked as it spread throughout the population causing mass death. There are treatments available now that can alleviate the effects of the virus and save the lives of those infected by the swine flu.. The H1N1 virus cannot be treated by the use of antibiotics. Antibiotics are used to treat bacterial infections and issues and are therefore useless when fighting a virus. However there are ways to alleviate the pains that are caused by the virus. Common symptoms of the H1N1 virus include: body aches, cough, diarrhea, sore throat, vomiting, chills, fever, fatigue, runny nose and headaches. Common over the ...
this is the host shift of the influenza A H1N1...if you can see, there are a red line is a connection between human and pig, so you can think for yourselves about that. take a look at the antigenic shift, and then you will understand the virus better...this make no sense, but it will make a big change ...
AbstractBackgroundCovariation is an essential process that leads to coevolution of parts of proteins and genomes. In organisms subject to strong selective pressure, coevolution is central to keep the balance between the opposite requirements of antigenic variation and retention of functionality. Being the viral component most exposed to the external environment, the HIV-1 glycoprotein gp120 constitutes the main target of the immune response. Accordingly its more external portions are characterised by extensive sequence heterogeneity fostering constant antigenic variation.ResultsWe report that a single polymorphism, present at the level of the viral population in the conserved internal region C2, was sufficient to totally abolish Env functionality when introduced in an exogenous genetic context. The prominent defect of the non-functional protein is a block occurring after recognition of the co-receptor CCR5, likely due to an interference with the subsequent conformational changes that lead to membrane
The TWiPsters solve the case of the Brazilian Immigrant With Heart Problems, and describe how genome organization controls trypanosome antigenic variation.
The numerous cases which were treated showed a positive clinical response in greater or lesser degree. The earliest cases were studied intensively and were readied for publication.. The tumors that responded to a greater degree to our treatment, as was expected, are the ones with the greatest degree of undifferentiation; because of their antigenic characteristics and because of the greater degree of dissimilarity between them and the genotypes and antigenic characteristics of normal cells, they have more probability of eliciting an efficient immunologic response.. Histological studies which were made give us certain possible mechanisms of action which correlate with the clinical response obtained.. Microscopic studies showed the almost complete delimitation of the tumoral areas by connective-vascular structures which seem to have diverse morphologies according to their proximity to the tumor and the level of their chronological development, having at first a thick endothelial wall with ...
Eosinophil Granule Proteins: Proteins found in EOSINOPHIL granules. They are primarily basic proteins that play a role in host defense and the proinflammatory actions of activated eosinophils.
Change in the Surface Antigen of a microorganism. There are two different types. One is a phenomenon, especially associated with Influenza Viruses, where they undergo spontaneous variation both as slow Antigenic drift and sudden emergence of new strains (Antigenic shift). The second type is when certain Parasites, especially trypanosomes, Plasmodium, and Borrelia, survive the immune response of the host by changing the surface coat (Antigen switching). (From Herbert et al., The Dictionary of Immunology, 4th ed ...
Citation. Lee AJ, Das SR, Wang W, Fitzgerald T, Pickett BE, Aevermann BD, Topham DJ, Falsey AR, Scheuermann RH. Diversifying Selection Analysis Predicts Antigenic Evolution of 2009 Pandemic H1N1 Influenza A Virus in Humans.. Journal of Virology. 2015 May 01; 89: 5427-40.. External Citation. Abstract. Although a large number of immune epitopes have been identified in the influenza A virus (IAV) hemagglutinin (HA) protein using various experimental systems, it is unclear which are involved in protective immunity to natural infection in humans. We developed a data mining approach analyzing natural H1N1 human isolates to identify HA protein regions that may be targeted by the human immune system and can predict the evolution of IAV. We identified 16 amino acid sites experiencing diversifying selection during the evolution of prepandemic seasonal H1N1 strains and found that 11 sites were located in experimentally determined B-cell/antibody (Ab) epitopes, including three distinct neutralizing Caton ...
Influenza A virus can mutate in two ways: antigenic drift or adaptive mutation, whereby the existing antigen transformed and antigenic shift or mutation of the mating process of two or more kinds of antigens. Antigenic drift, causing a small mutations in the flu virus from year to year, which attacks the human immune system but not completely. In contrast, the new H1N1 strain emerged in a way antigenic shift in pigs in Mexico ...
Schistosomes have an outer tegument that protects them from the host immune system. Parasite antigens expressed on or within the surface layer of the tegument have been suggested to be potential vaccine targets such as tetraspanin 23 (TSP23). Little is known about the evolution and diversity of tegumental antigens, an important consideration given that vaccines are being designed and are failing. Moreover, these antigens, including TSP23, are in direct contact with the host immune system, and so accelerated and adaptive evolution may be occurring. Species of Schistosoma infect a variety of definitive hosts. The way in which these hosts are shaping the evolution of antigens across different species of Schistosoma needs investigating. Much attention has been focussed on the production of an effective multi-species vaccine against the schistosomes, and there has been little success in absolute clearance or even establishment of continued immune memory post-infection. The aim of this study was ...
TY - JOUR. T1 - Epidemics in Competition. T2 - Partial Cross-Immunity. AU - Andreasen, Viggo. PY - 2018. Y1 - 2018. N2 - The competition between two pathogen strains during the course of an epidemic represents a fundamental step in the early evolution of emerging diseases as well as in the antigenic drift process of influenza. The outcome of the competition, however, depends not only on the epidemic properties of the two strains but also on the timing and size of the introduction, characteristics that are poorly captured by deterministic mean-field epidemic models. We describe those aspects of the competition that can be determined from the mean-field models giving the range of possible final sizes of susceptible hosts and cumulated attack rates that could be observed after an epidemic with two cross-reacting strains. In the limit where the size of the initial infection goes to zero, the possible outcomes lie on a (one dimensional) curve in the outcome space.. AB - The competition between two ...
Brunham, R C, F A Plummer, and R S Stephens. "Bacterial antigenic variation, host immune response, and pathogen-host coevolution.." Infection and Immunity 61.6 (1993): 2273-2276. Web. 19 Jan. 2020. ...
View Notes - 10-07_Culture_Exists_2 from ANTHRO 186P at UCLA. Culture exists Three sources of variation Much variation is not environmental Much variation not due to institutions w w Cultures
Pathogens that evade adaptive immunity typically exhibit antigenic variation. By contrast, it appears that although the chronic human tuberculosis (TB)-causing pathogen Mycobacterium tuberculosis needs to counter host T cell responses, its T cell epitopes are hyperconserved. Here we present an extensive analysis of the T cell epitopes of M. tuberculosis. We combined population genomics with experimental immunology to determine the number and identity of T cell epitope sequence variants in 216 phylogenetically diverse strains of M. tuberculosis. Antigen conservation is indeed a hallmark of M. tuberculosis. However, our analysis revealed a set of seven variable antigens that were immunogenic in subjects with active TB. These findings suggest that M. tuberculosis uses mechanisms other than antigenic variation to evade T cells. T cell epitopes that exhibit sequence variation may not be subject to the same evasion mechanisms, and hence vaccines that include such variable epitopes may be more ...
Antigenic variation by variant surface glycoprotein (VSG) coat switching in African trypanosomes is one of the most elaborate immune evasion strategies found among pathogens. Changes in the identity of the transcribed VSG gene, which is always flanked by 70-bp and telomeric repeats, can be achieved either by transcriptional or DNA recombination mechanisms. The major route of VSG switching is DNA recombination, which occurs in the bloodstream VSG expression site (ES), a multigenic site transcribed by RNA polymerase I. Recombinogenic VSG switching is frequently catalyzed by homologous recombination (HR), a reaction normally triggered by DNA breaks. However, a clear understanding of how such breaks arise-including whether there is a dedicated and ES-focused mechanism-is lacking. Here, we synthesize data emerging from recent studies that have proposed a range of mechanisms that could generate these breaks: action of a nuclease or nucleases; repetitive DNA, most notably the 70-bp repeats, providing ...
Trypanosoma brucei, a causative agent of African sleeping sickness in humans and nagana in animals, constantly changes its dense variant surface glycoprotein (VSG) coat to avoid elimination by the immune system of its mammalian host, using an extensive repertoire of dedicated genes. Although this process, referred to as antigenic variation, is the major mechanism of pathogenesis for T. brucei, the dynamics of VSG expression in T. brucei during an infection are poorly understood. In this thesis, I describe the development of VSG-seq, a method for quantitatively examining the diversity of expressed VSGs in any population of trypanosomes. Using VSG-seq, I monitored VSG expression dynamics in vivo during both acute and chronic mouse infections. My experiments revealed unexpected diversity within parasite populations, and the expression of as much as one-third of the functional genomic VSG repertoire after only one month of infection. In addition to suggesting that the host-pathogen interaction in T.
Research in the Totten group focuses on the molecular biology, pathogenesis, and disease associations of the recently discovered STD pathogen, Mycoplasma genitalium. Their finding that this bacterium can persist for months, if not years, in infected women lead to our hypothesis that this pathogen evades the host immune response in part by antigenically varying two of its immunogenic surface-exposed proteins. Supporting this hypothesis, they have shown that the sequences of the genes encoding these proteins evolve using reciprocal recombination with non-coding homologous DNA distributed throughout its minimal chromosome. Further, contrary to the accepted wisdom that this bacterium contains few regulatory genes, they have shown that recombination leading to antigenic variation is regulated at the transcriptional, post-transcriptional, and translational levels. The novel recombination and regulatory mechanisms of antigenic variation, the biologic significance of the resulting antigenic variants, ...
Neisseria meningitidis is the major cause of bacterial meningitis worldwide. The genome of this pathogen contains >40 phase variable loci whose expression is regulated by tandem DNA repeat tracts. Majority of these loci encode OMPs, which are potential targets for host innate and adaptive immune responses. An analysis for the distribution, frequency and role of PV of these genes is relevant in determining their virulence association and suitability as a future vaccine candidate. The project investigated the combined distribution, frequency and PV status of two important genes, hpuAB and hmbR, in disease (n=221) and carriage (n=305) isolates. Strains with both genes or only hmbR were present at similar frequencies among disease isolates as compared with carriage isolates. However, >90 % of isolates from CC5, CC8 and CC11 (CCs with the highest disease to carriage ratios) contained both genes. Strains with only hpuAB gene were under-represented among disease isolates, possibly due to the receptor ...
Vaccination against foot-and-mouth disease (FMD) represents an essential element in controlling and combating outbreaks, which can otherwise have disastrous consequences such as during the FMD outbreak in the UK in 2001. This is pertinent to regions in large parts of the developing world in which the FMD virus (FMDV) is endemic, as well as during an epidemic in FMDV-free areas such as Europe. Nevertheless, successful vaccination against FMDV requires selection of the appropriately matching vaccine strain providing protection against a particular circulating field virus. This problem originates from the existence of seven known serotypes of FMDV, with which a high antigenic variation of the virus is observed. In addition, subtypical antigenic variation within a serotype is under constant evolutionary change due to the high mutation rate of FMDV. For these reasons, continuous vaccine testing and modification in the light of recent antigenic changes to the virus is required. Traditionally, vaccines ...
darcoda at telerama.lm.com (S. Frog) wrote: , , , Hi, and all that. , , Im not sure if this is the proper place to raise this question, , and forgive me if it isnt, but I have a question about the flu. , Actually, three questions: , Is the flu a retrovirus? , If it isnt a retrovirus, do I have a faulty definition of what a , retrovirus is? , Lastly, is it true that the flu has only been around for like a , hunred years or so? And that it mutated from something else, which is , why human has so little resistence to it when the influenza epidemic , roared through just after world war I? , , , Thanks. :) , , , , , S. Frog , -- , , , .. The agent which causes many cases of the flu is called influenza. It is a member of the Orthomyxoviridae. These viruses have a segmented, single stranded RNA genome. Their segmented genome enables them to undergo a special kind of mutation (actually it is segment reassortment) called antigenic shift, which causes the pandemics in human medicine. Many species ...
Contingency genes are common in pathogenic microbes and enable, through pre-emptive mutational events, rapid, clonal switches in phenotype that are conducive to survival and proliferation in hosts. Antigenic variation, which is a highly successful survival strategy employed by eubacterial and eukaryotic pathogens, involves large repertoires of distinct contingency genes that are expressed differentially, enabling evasion of host acquired immunity. Most, but not all, antigenic variation systems make extensive use of subtelomeres. Study of model systems has shown that subtelomeres have unusual properties, including reversible silencing of genes mediated by proteins binding to the telomere, and engagement in ectopic recombination with other subtelomeres. There is a general theory that subtelomeric location confers a capacity for gene diversification through such recombination, although experimental evidence is that there is no increased mitotic recombination at such loci and that sequence ...
In addition to avoiding destruction by modulating DNA-Repair pathways, viruses also alter other aspects of the cells defense such as cell surface markers. CMV and adenoviruses decrease the expression of a cells MHC recognition markers which decreases the ability of the immune system to respond to infections that is highly characteristic of the immune system in senescence (DNA-Damage-Response np). One factor is the loss of the CD28 marker; when CD28 isnt expressed, antigen-presenting cells like macrophages no longer recognise the T cell and thus arent able to alert the immune cell to danger (de Grey 207). Some viruses like HIV are able to prevent detection from the immune system by restricting the expression of virus antigens as well as having wide antigen variation (DNA-damage-response). Furthermore, there are viruses that modify other signaling pathways that lead affects lymphocyte and macrophage (which is an anti-gen presenting cell) functions that lead to immunosupression ...
Then is this host specific antigenic variation due to different subspecies of P.carinii infecting their particular favorite flavor of host? Or is there one P.carinii changing its disguise to suit its situation (Like the elusive pimpernel)? Do the authors of this splendid sounding article offer an explanation? My library doesnt carry that journal. Doesnt carry much of anything not relating to engineering, actually. Regards Simon ______________________________ Reply Separator _________________________________ Subject: RE: Re[2]: P.carinii Author: [email protected] at Internet Date: 11/12/98 7:14 PM Host species-specific antigenic variations have been reported, according to the article I cited. Pigs are not dogs are not rats are not people! -----Original Message----- From: [email protected] [SMTP:[email protected]] Sent: Thursday, November 12, 1998 12:27 PM To: [email protected] Subject: Re[2]: P.carinii Forgive my stupidity, but wont any antibody to P.carinii label ...
A Mr 32,000 integral membrane protein has previously been identified on erythrocytes bearing the Rh(D) antigen and is thought to contain the antigenic variations responsible for the different Rh phenotypes. To study it on ...
5/4/2009 10:24:08 PM Flu viruses change slightly from year to year. This is called antigenic drift. This is what the committee that determines what the
In malaria‐endemic areas, a nagging issue is the failure of naturally exposed individuals to develop sterile long‐lasting protective immunity. This may be due to several factors including the stage specificity of parasite antigen expression, the antigenic variability among field parasites, and the profound immune dysregulation caused by pre‐erythrocytic and erythrocytic stages (Renia & Goh, 2016; Scholzen & Sauerwein, 2016; Van Braeckel‐Budimir et al, 2016). These factors could also contribute to explain why despite tremendous investments and years of research, progress on the vaccination front has been only modest. Clinical efficacy of the most advanced subunit vaccine candidate against P. falciparum (RTS,S) is limited and quickly wanes over time (Olotu et al, 2016). Hopes are emerging from whole attenuated sporozoite vaccination strategies (Sissoko et al, 2017), but the disappointing RTS,S results combined with the fact that vaccine research on P. vivax is only beginning (Tham et al, ...
Human rhinoviruses (HRVs), a genus of the Picornaviridae family, are the most frequent etiological agents of common colds (Rueckert, 1996). Rhinoviruses are small, icosahedral viruses, with an average diameter of 300 Å and a molecular mass of ∼8.5 × 106 Da. They are composed of a protein shell that encapsidates a single, positive RNA strand of ∼7000 bases. The capsid is built from 60 copies each of four viral proteins. The three larger proteins, VP1, VP2 and VP3 (∼250 amino acids, 30 kDa each), form the external surface of the virus, whereas VP4 (70 amino acids, 6 kDa) is an internal protein located at the interface between the capsid and genome (Rossmann et al., 1985).. With ,100 different serotypes identified to date, HRVs exhibit remarkable antigenic variability. To produce infection, HRVs must first attach to a cellular receptor. The major group of HRVs, consisting of ∼90 serotypes, utilizes the cell surface glycoprotein, intercellular adhesion molecule‐1 (ICAM‐1), as its ...
Interested in discovering how trypanosomes undergo antigenic variation? If the answer is yes - we have a postdoctoral position available in the Trypanosome Molecular Biology group with Lucy Glover. In our group we study how the trypanosomes control expression of the variant surface glycoprotein from the fly to the mammalian host, and the the role of DNA repair and recombination in antigenic variation and immune evasion in African trypanosomes We are located in the Department of Parasites and Insect Vectors at the Institute Pasteur in Paris, which provides an excellent international scientific environment and state-of-the-art core facilities including high throughput sequencing, and imaging technologies.. ...
The 70 bp repeats were first implicated as recombination hotspots able to initiate the VSG copying process more than 25 years ago [6]. In order to test the hypothesis that a DSB adjacent to these repeats could initiate a switch, Boothroyd et al. [5] placed a yeast meganuclease (I-SceI) recognition sequence in the active expression site immediately adjacent to the 70 bp repeats; the trypanosome strain was also modified to express an inducible copy of the meganuclease [5]. Induction of I-SceI expression generated a DSB in around 1% of the cells, which increased the switching frequency by around 250-fold. In contrast, a DSB elsewhere in the expression site or after deletion of the 70 bp repeats did not increase switching frequency. These data indicate that both the location of the DSB next to the repeats and the repeats themselves are critical to increased switching.. Boothroyd et al. [5] then analyzed 18 of the switched progeny, revealing that they had all lost the active VSG, replacing it with ...
Author Summary The molecular evolution of any organism is described by changes in the genotype resulting from genetic drift or selection to maintain or establish fitness under the given environmental conditions. Identification of phenotype-defining changes and their distinction from (near-) neutral (hitchhikers) ones is a fundamental challenge in genome research. The standard approach involves time- and cost-intensive mutation experiments, which are typically low throughput, due to their experimental nature. We have developed a computational method for the inference of phenotypic impact of genotypic changes that is applicable to any system, within or across species, where homologous genetic sequences and associated pairwise phenotype distances are available. We demonstrate the accuracy of our method by application to the human influenza A (H3N2) virus. This exemplary system is of particular interest, as recognizing changes in the antigenic phenotype and a viral strains capability to evade pre
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The primary focus of the Montelaro lab is to elucidate the intricate interactions between viral pathogens and host immune responses to determine the mechanisms by with host immunity contributes to protection and disease and to serve as a basis for the development of effective vaccines. A particular interest of the lab is to develop effective strategies to overcome the challenge of natural viral antigenic variation that has evolved as a common complication to the development of effective vaccines to important viral diseases, including those related to biodefense and emerging infectious diseases. Systems currently under investigation include HIV-1 and related animal lentiviruses (SHIV, SIV, and EIAV). Studies in these systems include investigation of the nature and role of antigenic variation during infection, the development of novel assays to characterize virus-specific innate, humoral, and cellular immune responses, and the design of engineered immunogens for effective vaccination against ...
Identification of nuclear proteins that interact differentially with Plasmodium falciparum var gene promoters.: The Plasmodium falciparum virulence factor PfEMP
A novel strategy to predict the antigenic evolution of circulating influenza viruses and more precisely anticipate seasonal flu strains has been developed.
Our research at the London School of Hygiene and Tropical Medicine focuses on antigenic variation, drug action and resistance and the application of genetic screens to the African trypanosome, Trypanosoma brucei. See movie (5 min) on disease caused by African ...
... An analysis is presented for the horizontal displacement and rotation of a vertical pile subjected to lateral loading and moment, and situated in an ideal elastic mass. Influence factors are presented for a wide range of pile flexibilities and length-to-diameter ratios, for both free-head and fixed-head piles. Comparisons between the elastic solutions and the corresponding solutions obtained from the subgrade reaction theory show that the latter considerably overestimates the displacement and rotation of the pile, but gives a reasonable estimate of the moments in the pile. The elastic analysis is extended to include the effect of local yield between the soil and the pile; the load-displacement relationship for relatively flexible piles is found to be markedly influenced by local yield. The characteristics of behavior indicated by the theoretical solutions agree reasonably well with those reported from measurements on full-scale piles.
Yet crucial advances in toxicology also occurred within other NIH laboratories, led during pioneers such as Bernard Brodie and Julius Axelrod and later continued at hand investigators such as JR Mitchell, D Jollow and JR Gillette. There are assorted institutes all across the world, which gather genome data, for benchmark, to discover why united treatment in regard to a genetic malady helps one untiring, but shows no or less to all intents on another. This substance inferior intimacy, lower communications, and much fights discount dapoxetine 90mg with mastercard erectile dysfunction at age 25. J Biol Chem 270:7241В-7250 Prucca CG, Slavin I, Quiroga R, Elias EV, Rivero FD, Saura A, Carranza PG, Luj?n HD (2008) Antigenic variation in Giardia lamblia is regulated by RNA interference. As infants fit more expressive, they jeopardy wound from falls down stairs and afar chairs, tables, and other structures. Its an surprising process, this on-going detoxification of your consistency order cialis 10mg ...
... Topics covered include the subversion of complement, NK cell function, mucosal innate immune response, antigenic variation, masking of epitopes, the use of decoys, molecular mimicry, evasion/subversion mechanisms used by bacteria, helminths, viruses, and the measles model system.
Problems & Puzzles: Puzzles Puzzle 92. A pile of prime-spheres Days ago my friend Enoch Haga and me starting puzzling each other to construct a pile of balls (a tetrahedron) with the following properties: a) every ball contains a distinct prime, b) each prime-ball must be the sum of the prime numbers contained in the three balls from the immediate inferior level and in contact with the mentioned prime-ball. Can you imagine a pile of balls? A new friend of these pages, Chuck Henry, kindly and quickly provided several beautiful photos generated by him that should help to visualize a pile of balls like the one we are talking about. Please click here 1 and here 2 (*). Question: Get the least solution for a pile of n levels, for n=5, 6 & 7. ...
M. Soriani, P. Petit, R. Grifantini, R. Petracca, G. Gancitano, E. Frigimelica, F. Nardelli, C. Garcia, S. Spinelli, G. Scarabelli, S. Fiorucci, R. Affentranger, M. Ferrer-Navarro, M. Zacharias, G. Colombo, L. Vuillard, X. Daura and G. Grandi. Exploiting antigenic diversity for vaccines design : the Chlamydia ArtJ paradigm. J. Biol. Chem, 2010, 285, 30126-30138. ...
There are numerous possible causes of piles. In fact, they are not nervous and not hazardous. If youre on the lookout for piles remedy or strategies to do
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... Did you see any soft bumps or lumps in your anus? Well, they are most likely piles. External and prolapsed internal piles are usually soft, moist grapes around your anal opening. They may cause itching and pain during passing stool.
Useful Tips For The Treatment of Piles. Piles are considered to be one of the common problems, a number of people are endurance from. Dealing with..
Piles or hemorrhoids are a very common condition that most people suffer. It creates much discomfort and pain especially when going to the toilet. Learn more about piles here.
What are some effective remedies for piles? If youre looking for piles treatment options, youve come to the right place. Read more here.
The MOVAX side grip pile driver is based on MOVAXs Modular System and thus capable of handling a wide variety of piles [linkki]. In order to select the correct arms, clamps and pads information is needed about the main type of piles to be driven, but also whether there is a need to drive also other type of piles, now or in the future ...
The current measures to control foot-and-mouth disease (FMD) include vaccination, movement control and slaughter of infected or susceptible animals. One of the difficulties in controlling FMD by vaccination arises due to the substantial diversity found among the seven serotypes of FMD virus (FMDV) and the strains within these serotypes. Therefore, vaccination using a single vaccine strain may not fully cross-protect against all strains within that serotype, and therefore selection of appropriate vaccines requires serological comparison of the field virus and potential vaccine viruses using relationship coefficients (r1 values). Limitations of this approach are that antigenic relationships among field viruses are not addressed, as comparisons are only with potential vaccine virus. Furthermore, inherent variation among vaccine sera may impair reproducibility of one-way relationship scores. Here, we used antigenic cartography to quantify and visualize the antigenic relationships among FMD serotype ...
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Lien vers Pubmed [PMID] - 22100161. Cell Host Microbe 2011 Nov;10(5):451-63. Many microbial pathogens, including the malaria parasite Plasmodium falciparum, vary surface protein expression to evade host immune responses. P. falciparium antigenic variation is linked to var gene family-encoded clonally variant surface protein expression. Mututally exclusive var gene expression is partially controlled by spatial positioning; silent genes are retained at distinct perinuclear sites and relocated to transcriptionally active locations for monoallelic expression. We show that var introns can control this process and that var intron addition relocalizes episomes from a random to a perinuclear position. This var intron-regulated nuclear tethering and repositioning is linked to an 18 bp nuclear protein-binding element that recruits an actin protein complex. Pharmacologically induced F-actin formation, which is restricted to the nuclear periphery, repositions intron-carrying episomes and var genes and ...
Objectives. This study tested the hypothesis, first proposed by Chaussinand, that individual-level immunity acquired from exposure to tuberculosis may have contributed to the disappearance of leprosy from western Europe. Methods. The epidemiological consequences of cross-immunity were assessed by the formulation of a mathematical model of the...
We investigated if any var types were shared between the three patients. This was not expected as previous studies have shown minimal overlap in the expressed var repertoire between patients (Kaestli et al., 2004; Bull et al., 2005; Kyriacou et al., 2006). There was only one var type shared between PM55 and PM32, detected at two copies in the heart of PM55 and in all four organs of PM32. There were no var types shared between PM30 and PM55. Surprisingly, there was substantial overlap in the var types detected in PM30 and PM32, with 20 DBLα/var types detected in both cases (Fig. 1). These sequences were identical between the two patients. It is important to note that shared DBLα sequence does not necessarily imply that that entire var genes represented by each tag are identical. However, we will continue to refer to these as var types for continuity.. The shared var types accounted for 20% of PM30 var types and 26% of PM32 var types, compromising 61% and 32% of all clones detected in each ...
Dr. Beasleys research currently focuses on the molecular basis of virulence and antigenic variations between strains of West Nile virus. His labs wider research activities include studies related to the development of improved diagnostic and therapeutic reagents and vaccines for flaviviruses and other arboviruses. Dr. Beasley is Co-Director of the Keiller/GNL BSL3 laboratories, Director of the GNL Regulatory Services Core, and directs research activities associated with an NIH-sponsored animal models contract to undertake GLP compliant animal and in vitro studies ...
Pile weatherstripping (20) having an integral fin is made by wrapping a fin material around a traveling mandrel or band (14), winding pile material around the fin material and the band (14), attaching a pair of backer elements to the pile material along opposite edges of the band, and then cutting the fin material and the pile material to produce simultaneously two pile weatherstrips. Stationary and traveling elements may be employed to facilitate cutting and produce fin above the pile weatherstrips (20).
In view of the participation of vascular endothelial cells (EC) in a wide range of normal and pathological conditions, phenotypic heterogeneity of EC is an important concept for consideration:...
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Hi, my wife just showed me the video... watching your shuffling at the beginning you can figure out that the random part does not at all change the positions of the aces in the resulting pile. The random set of x cards is on the right pile, the remaining 15-x cards on the middle pile under the next ace. In the end the middle pile goes on the right pile making it exactly the same 15 cards between the two aces that were on the middle pile before - just randomly restacked (only those 15 cards) - the same thing happens with the other random part and the right pile. To puzzle the audience more you do the 4 cards-thing at the end ...
Its easy to make a quick stop at the deli counter, come home and pile sliced sandwich meats on a bun. But these light summer sandwiches, which have all the crunch of a salad, take little time to
Efficient acquisition and transmission of Borrelia burgdorferi by the tick vector, and the ability to persistently infect both vector and host, are important elements for the life cycle of the Lyme disease pathogen. Previous work has provided strong evidence implicating the significance of the vls locus for B. burgdorferi persistence. However, studies involving vls mutant clones have thus far only utilized in vitro-grown or host-adapted spirochetes and laboratory strains of mice. Additionally, the effects of vls mutation on tick acquisition and transmission has not yet been tested. Thus, the importance of VlsE antigenic variation for persistent infection of the natural reservoir host, and for the B. burgdorferi enzootic life cycle in general, has not been examined to date. In the current work, Ixodes scapularis and Peromyscus maniculatus were infected with different vls mutant clones to study the importance of the vls locus for the enzootic cycle of the Lyme disease pathogen. The findings highlight the
Intragenic recombination between the single complete pilin gene (expression locus) and multiple, distinct, partial pilin gene copies (silent, storage loci) is thought to account for the generation of pilus antigenic diversity and piliation phase (on-off) changes exhibited by Neisseria gonorrhoeae. The mechanisms operating in the genomic rearrangements associated with these forms of pilus variation were investigated through the study of isogenic strains of gonococci bearing either wild-type or altered recA alleles. Examination of the rates of pilus phase variation and the genetic basis for changes in piliation status displayed by these strains show that recA mediated homologous recombination is required for these high frequency events and confirm that the nonpiliated state results from mutations in the expressed pilin gene. In a strain that is deficient in recA mediated homologous recombination, pilus phase variation occurs at a 100-1000-fold reduced rate and results predominantly from one class ...
Influenza B virus is almost exclusively a human pathogen, and is less common than influenza A. The only other animal known to be susceptible to influenza B infection is the seal.[12] This type of influenza mutates at a rate 2-3 times lower than type A[13] and consequently is less genetically diverse, with only one influenza B serotype.[6] As a result of this lack of antigenic diversity, a degree of immunity to influenza B is usually acquired at an early age. However, influenza B mutates enough that lasting immunity is not possible.[14] This reduced rate of antigenic change, combined with its limited host range (inhibiting cross species antigenic shift), ensures that pandemics of influenza B do not occur.[15]. ...
Abstract A feature of fascioliasis in mice and rats is incomplete and generally poor resistance to reinfection. The possibility exists that population heterogeneity amongst Fasciola hepatica parasites (in characteristics such as antigenic variability and infectivity) contributes to the incomplete resistance expressed by already infected rodents to challenge infection. Using different exposure regimes, mice and rats were dosed with infective metacercariae of different single snail-derived clones and challenged with the same or different clonal parasites. The results clearly demonstrate that no better resistance to reinfection is seen with parasites of the homologous clone than with heterologous clone challenge. Thus the poor resistance to reinfection seen in fascioliasis cannot be ascribed readily to antigenic or infectivity differences between clonal metacercariae.
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It has long been established that African trypanosomes possess a dense protein surface coat that must offer protection from destruction by the host immune system. The coat is comprised of close to only one GPI-anchored surface protein from a large family of variant surface glycoproteins (VSGs). This VSG is thought to form an impervious, physical barrier on the cell surface, thus protecting the underlying proteins from immune attack. It is itself highly immunogenic, but bound antibodies are passively cleared from the cell surface by hydrodynamic drag forces. Importantly, the expressed VSG can be replaced by another, antigenically distinct, member of the large family of VSGs in a process known as antigenic variation.. Despite the N-terminal domain structure of one VSG, MITat1.2, having been solved and published in 1990, the structure of a complete VSG has proven difficult to obtain. In fact, at the start of this study, structural data was only available for the individual domains of two of the ...
Foot-and-mouth disease has been known for at least four centuries. The earliest reports of its occurrence are from Italy; it did not reach England until 1839. Its occurrence in South America was first described in 1871 and is probably linked to the movement of infected cattle from Europe to that part of the world. The earliest reports of the disease in Asia and Africa date from 1842 and 1892 respectively. The causal agent of the disease, a virus belonging to the family Picornaviridae, was discovered by Loeffler & Frosch in 1897; its antigenic diversity was described in the early 1920s. Seven serologically distinct types of the virus are now recognized, thus rendering the task of vaccination more complex, particularly as there is also considerable antigenic diversity within the serotypes. Nevertheless, good inactivated vaccines are available and, as demonstrated in western Europe over the last 30 years, these have proved to be extremely effective when applied prophylactically in efficiently ...
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Monoclonal antibodies specific for selected species complexes of Leishmania have been employed for the characterization of several representative strains of Leishmania isolated from different hosts and localities in the Americas. In the past 15 years, data have been accumulated concerning (i) the specificities of a number of these monoclonal antibodies and (ii) the antigenic variation (level of the expressed antigenic determinants) occurring among New World Leishmania species or strain variants as recognized by the monoclonal antibodies. This report is an attempt to summarize in brief the data accumulated to date on these points and to indicate the directions for future applications of these specific monoclonal antibodies for identification of leishmanial isolates ...
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A simple predictive model estimates the fitness $f$ of virus $i$ as. $$\hat{f}_i = \beta^\mathrm{ep} \, f_i^\mathrm{ep} + \beta^\mathrm{ne} \, f_i^\mathrm{ne}$$. where $f_i^\mathrm{ep}$ measures cross-immunity via substitutions at epitope sites and $f_i^\mathrm{ep}$ measures mutational load via substitutions at non-epitope sites.. ...
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Trypanosoma brucei is a major cause of death in humans (sleeping sickness) and livestock in some parts of Africa. It is caused by a parasite Trypanosoma brucei, which is transmitted by the Tsetse fly. Current drugs are toxic and vaccine development is unlikely because the parasites undergo antigenic variation. Antigenic variation involves the switching of Variant Surface Glycoproteins (VSGs), which depends on fatty acids for surface expression. Acetyl-CoA Carboxylase (ACC) catalyzes the first committed step of fatty acid synthesis and hence is a potential therapeutic target. Our studies demonstrated that inhibition of ACC expression causes a growth defect in insect procyclic form (PF) parasites in low lipid condition and reduced mammalian bloodstream form (BF) infection in mice. Under lab growth conditions, we observed regulation of ACC by environmental lipids in PFs but not BFs. In BFs, we showed that ACC is required for the elevated endocytosis needed for the parasite to avoid antibody-dependent
Antigenic variation is a hallmark of influenza virus that allows the virus to evade host defenses. Consequently influenza vaccines need to be reformulated frequently to keep up with changing viruses. In contrast, antigenic variation is not a hallmark of poliovirus - the same poliovirus vaccines have been used for nearly 60 years to control infections by this virus. An exception is a poliovirus type 1 that caused a 2010 outbreak in the Republic of Congo.. The 2010 outbreak (445 paralytic cases) was unusual because the case fatality ratio of 47% was higher than typically observed (usually less than 10% of patients with confirmed disease die). The first clue that something was different in this outbreak was the finding that sera from some of the fatal cases failed to effectively block (neutralize) infection of cells by the strain of poliovirus isolated during this outbreak (the strain is called PV-RC2010). The same sera effectively neutralized the three Sabin vaccine viruses as well as wild type 1 ...
Monoallelic expression within a gene family is found in pathogens exhibiting antigenic variation and in mammalian olfactory neurons. Trypanosoma brucei, a lethal parasite living in the human bloodstream, expresses variant surface glycoprotein (VSG) from 1 of 15 bloodstream expression sites (BESs) by virtue of a multifunctional RNA polymerase I. The active BES is transcribed in an extranucleolar compartment termed the expression site body (ESB), whereas silent BESs, located elsewhere within the nucleus, are repressed epigenetically. The regulatory mechanisms, however, are poorly understood. Here we show that two essential subunits of the basal class I transcription factor A (CITFA) predominantly occupied the promoter of the active BES relative to that of a silent BES, a phenotype that was maintained after switching BESs in situ. In these experiments, high promoter occupancy of CITFA was coupled to high levels of both promoter-proximal RNA abundance and RNA polymerase I occupancy. Accordingly, ...
Human norovirus (NoV) strains cause a considerable number of outbreaks of gastroenteritis worldwide. Based on their capsid gene (VP1) sequence, human NoV strains can be grouped into two genogroups (GI and GII) and at least 14 GI and 17 GII genotypes (GI/1-14 and GII/1-17). Human NoV strains cannot be propagated in cell-culture systems, but expression of recombinant VP1 in insect cells results in the formation of virus-like particles (VLPs). In order to understand NoV antigenic relationships better, cross-reactivity among 26 different NoV VLPs was analysed. Phylogenetic analyses grouped these NoV strains into six GI and 12 GII genotypes. An antibody ELISA using polyclonal antisera raised against these VLPs was used to determine cross-reactivity. Antisera reacted strongly with homologous VLPs; however, a number of novel cross-reactivities among different genotypes was observed. For example, GI/11 antiserum showed a broad-range cross-reactivity, detecting two GI and 10 GII genotypes. Likewise, GII/1, GII
Vsp surface lipoproteins are serotype-defining antigens of relapsing fever spirochetes that undergo multiphasic antigenic variation to avoid the immun
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Bleeding piles occur most commonly inside the rectal canal but they can occur externally as well. Bleeding piles can indicate a serious amount of damage to the affected area. Bleeding piles are a sign that the hemorrhoid has developed significantly and corrective action must be taken. Piles can affect people you and old. They are…
Three men in a lumberyard help hoist a board onto a low pile of boards while a fourth man stands to the right behind a smaller pile of similar boards on a wheeled cart that runs along a track. On either side of the track are many other piles of ...
You know how they say youve got to endure a whole lot of nos until you get that single magical yes? Well, another no was added to the pile this week in the form of a Pass rating from an industry professional regarding my western spec. And to make it that much better, the Pass was…
A Culture that views pigs as inanimate piles of protoplasmic structure to be manipulated however cleverly the human mind can conceive will view its citizens the
Influenza may be a common infection but it can bring serious complications for children and the sick and elderly. INFLUENZA is a common infection that affects many people. It is caused by RNA viruses of the orthomyxoviridae family. The influenza viruses are classified into types A, B and C based on their core proteins. Type A viruses infect humans and mammals such as pigs and horses, and birds. Type B and C viruses usually affect humans. Type A and B viruses are common causes of acute respiratory infections. Type A virus is the main cause of epidemics and pandemics. The Spanish flu in 1918 resulted in an estimated death of 40 million worldwide. The Asian influenza pandemic of 1957 and the Hong Kong influenza pandemic of 1968 caused significant mortality worldwide. The virus often mutates. Minor mutations (antigenic drift) are frequent and cause repeated outbreaks. Major mutations (antigenic shift) are rare and are due to reassortment of genetic material from different A sub-types. When ...
Influenza vaccines are continuously modified to adjust to the virus antigenic shifts or drifts, and its safety profile may vary. While generally considered safe, influenza vaccines have been associated in the past with increases in cases of Guillain-Barré syndrome (1976) or with oculorespiratory syndrome (2001). The emergence of a novel strain of H1N1 influenza virus (pH1N1) has prompted health departments worldwide to prepare for mass vaccination campaigns with a new H1N1 pandemic vaccine. Following recommendations of the World Health Organization (WHO), Canada immunized its population with a dose-sparing adjuvanted vaccine. While the adjuvant developed by GlaxoSmithKline (GSK) has been administered to over 39 000 people, only a few hundred will have been vaccinated with the H1N1 formulation in clinical trials before the mass campaign was launched. With this small number, adverse events occurring at a rate , 1% will not be detected by these clinical trials.. Considering that most cases of ...
Influenza vaccines are continuously modified to adjust to the virus antigenic shifts or drifts, and its safety profile may vary. While generally considered safe, influenza vaccines have been associated in the past with increases in cases of Guillain-Barré syndrome (1976) or with oculorespiratory syndrome (2001). The emergence of a novel strain of H1N1 influenza virus (pH1N1) has prompted health departments worldwide to prepare for mass vaccination campaigns with a new H1N1 pandemic vaccine. Following recommendations of the World Health Organization (WHO), Canada immunized its population with a dose-sparing adjuvanted vaccine. While the adjuvant developed by GlaxoSmithKline (GSK) has been administered to over 39 000 people, only a few hundred will have been vaccinated with the H1N1 formulation in clinical trials before the mass campaign was launched. With this small number, adverse events occurring at a rate , 1% will not be detected by these clinical trials.. Considering that most cases of ...
We have recently proposed a new model for antigenic variation in Plasmodium falciparum that relies on a network of partially cross-protective immune responses to orchestrate this complex immune evasion process. In addition to exhibiting prolonged oscillations of single variants that resemble the sequential dominance of immunologically distinct antigenic types, the model implies that a higher efficacy of cross-reactive immunity actually increases the length of infection while reducing severity of disease. Here, we analyse the behaviour of a reduced system under conditions of perfect synchrony between variants to demonstrate that these features of this system can be attributed to the antagonism between cross-reactive and variant-specific responses.
Despite the many genomic sequences and gene annotations available, how genetic information is structured in any genome remains poorly understood. Eukaryotic parasites subtelomeres provide a unique system to tackle this question, as they are crucial effectors of adjacent contingency genes (including virulence genes) in these organisms, and as subtelomeric-sequence assemblies are available for most of them. Yet their intrinsic features have undermined so far a comprehensive analysis. An intuitive approach will be outlined, based on the integration of dot-plot analyses, of softwares publicly available and of Perl scripts developed locally. Its application demonstrates how in-depth large-scale annotation of junk DNA may help understanding the mechanisms underlying plasticity and mosaicism at the chromosomal ends, the mechanisms of allelic exclusion and antigenic variation observed among virulence-related genes, and foster convergence between experimental, evolutionary and in silico studies. Lastly, ...
A large number of Endotrypanum stocks (representing an heterogeneous population of strains) have been screened against a panel of monoclonal antibodies (MAbs) derived for selected species of Endotrypanum or Leishmania, to see whether this approach could be used to group/differentiate further among these parasites. Using different immunological assay systems, MAbs considered specific for the genus Endotrypanum (E-24, CXXX-3G5-F12) or strain M6159 of E. schaudinni (E-2, CXIV-3C7-F5) reacted variably according to the test used but in the ELISA or immunofluorescence assay both reacted with all the strains tested. Analyses using these MAbs showed antigenic diversity occurring among the Endotrypanum strains, but no qualitative or quantitative reactivity pattern could be consistently related to parasite origin (i.e., host species involved) or geographic area of isolation. Western blot analyses of the parasites showed that these MAbs recognized multiple components. Differences existed either in the ...
First there are the particular non-invasive procedures such as latex banding or even coagulation treatment. Latex banding involves placing a tight latex band around the pile, causing the pile to be able to shrivel up and fall off. This is a relatively safe method, but it can take up to a week to complete the process, during which time this could get quite intensive. Latex banding can only be used on piles of a certain size, because its not suitable for piles that are too small to get a good lock on neither for piles too large to get the latex music group around ...
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Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a family of proteins present on the membrane surface of red blood cells (RBCs or erythrocytes) that are infected by the malarial parasite Plasmodium falciparum. PfEMP1 is synthesized during the parasites blood stage (erythrocytic schizogony) inside the RBC, during which the clinical symptoms of falciparum malaria are manifested. Acting as both an antigen and adhesion protein, it is thought to play a key role in the high level of virulence associated with P. falciparum. It was discovered in 1984 when it was reported that infected RBCs had unusually large-sized cell membrane proteins, and these proteins had antibody-binding (antigenic) properties. An elusive protein, its chemical structure and molecular properties were revealed only after a decade, in 1995. It is now established that there is not one but a large family of PfEMP1 proteins, genetically regulated (encoded) by a group of about 60 genes called var. Each P. falciparum is ...
African sleeping sickness is a debilitating and often fatal disease caused by tsetse fly transmitted African trypanosomes. These extracellular protozoan parasites survive in the human bloodstream by virtue of a dense cell surface coat made of variant surface glycoprotein. The parasites have a repertoire of several hundred immunologically distinct variant surface glycoproteins and they evade the host immune response by antigenic variation. All variant surface glycoproteins are anchored to the plasma membrane via glycosylphosphatidylinositol membrane anchors and compounds that inhibit the assembly or transfer of these anchors could have trypanocidal potential. This article compares glycosylphosphatidylinositol biosynthesis in African trypanosomes and mammalian cells and identifies several steps that could be targets for the development of parasite-specific therapeutic agents. (C) 1999 Elsevier Science B.V. All rights reserved. ...

Plasmodium falciparum erythrocyte membrane protein 1 - WikipediaPlasmodium falciparum erythrocyte membrane protein 1 - Wikipedia

Kyes, S. A.; Kraemer, S. M.; Smith, J. D. (2007). "Antigenic variation in Plasmodium falciparum: Gene organization and ... Scherf, Artur; Lopez-Rubio, Jose Juan; Riviere, Loïc (2008). "Antigenic variation in Plasmodium falciparum". Annual Review of ... "The large diverse gene family var encodes proteins involved in cytoadherence and antigenic variation of Plasmodium falciparum- ... This variation gives rise to different types of PfEMP1. The DBL-CIDR combination in a particular type of PfEMP1 protein is ...
more infohttps://en.wikipedia.org/wiki/Plasmodium_falciparum_erythrocyte_membrane_protein_1

African TrypanosomiasisAfrican Trypanosomiasis

T. brucei effectively evade the human immune system by a fascinating genetically programmed system of antigenic variation. When ... the cells of the host from directly accessing the plasma membrane of the parasite and provide a means for antigenic variation ( ... results in the human because these parasites possess genetically programmed mechanisms for continuous antigenic variation. ...
more infohttp://www.bio.davidson.edu/courses/immunology/Students/spring2006/Ryan/TermPaper.html

Antigenic variation - WikipediaAntigenic variation - Wikipedia

Not to be confused with Antigenic drift or Antigenic shift.. Antigenic variation or antigenic alteration refers to the ... shows that some DNA viruses have the same high rates of antigenic variation as their RNA counterparts.[15] Antigenic variation ... Antigenic variation can occur by altering a variety of surface molecules including proteins and carbohydrates. Antigenic ... It is related to phase variation. Antigenic variation not only enables the pathogen to avoid the immune response in its current ...
more infohttps://en.wikipedia.org/wiki/Antigenic_variation

Immunogenetic mechanisms driving norovirus GII.4 antigenic variation.  - PubMed - NCBIImmunogenetic mechanisms driving norovirus GII.4 antigenic variation. - PubMed - NCBI

Immunogenetic mechanisms driving norovirus GII.4 antigenic variation.. Lindesmith LC1, Beltramello M, Donaldson EF, Corti D, ... Moreover, these data support the hypothesis that GII.4 norovirus evolution is heavily influenced by antigenic variation of ... Panel A: Amino acid variation of Epitopes A-E by GII.4 strain. Panel B: Predicted epitopes were expanded to include interacting ... To test if antigenic drift may contribute to GII.4 persistence, human memory B cells were immortalized and the resulting human ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/22615565?dopt=Abstract

Cytomegalovirus (CMV) Vaccines: Reinfection and Antigenic Variation - Full Text View - ClinicalTrials.govCytomegalovirus (CMV) Vaccines: Reinfection and Antigenic Variation - Full Text View - ClinicalTrials.gov

Cytomegalovirus (CMV) Vaccines: Reinfection and Antigenic Variation (CMV). The safety and scientific validity of this study is ...
more infohttps://clinicaltrials.gov/ct2/show/NCT03443791?term=cmv&

Genetic basis of Neisseria gonorrhoeae lipooligosaccharide antigenic variation. | Journal of BacteriologyGenetic basis of Neisseria gonorrhoeae lipooligosaccharide antigenic variation. | Journal of Bacteriology

Genetic basis of Neisseria gonorrhoeae lipooligosaccharide antigenic variation.. R J Danaher, J C Levin, D Arking, C L Burch, R ... Genetic basis of Neisseria gonorrhoeae lipooligosaccharide antigenic variation.. R J Danaher, J C Levin, D Arking, C L Burch, R ... Genetic basis of Neisseria gonorrhoeae lipooligosaccharide antigenic variation.. R J Danaher, J C Levin, D Arking, C L Burch, R ... Genetic basis of Neisseria gonorrhoeae lipooligosaccharide antigenic variation. Message Subject (Your Name) has forwarded a ...
more infohttps://jb.asm.org/content/177/24/7275/article-info

Antigenic variation of the Avian Myeloblastosis Virus obtained from chick embryo fibroblasts | SpringerLinkAntigenic variation of the Avian Myeloblastosis Virus obtained from chick embryo fibroblasts | SpringerLink

Chick Embryo Antigenic Variation Avian Myeloblastosis Virus Chick Embryo Fibroblast This work was done while the author was at ... Antigenic variation of the Avian Myeloblastosis Virus obtained from chick embryo fibroblasts. ...
more infohttps://link.springer.com/article/10.1007/BF01946182

Effects of recA Mutations on Pilus Antigenic Variation and Phase Transitions in Neisseria gonorrhoeae | GeneticsEffects of recA Mutations on Pilus Antigenic Variation and Phase Transitions in Neisseria gonorrhoeae | Genetics

Effects of recA Mutations on Pilus Antigenic Variation and Phase Transitions in Neisseria gonorrhoeae. Michael Koomey, Emil C. ... Effects of recA Mutations on Pilus Antigenic Variation and Phase Transitions in Neisseria gonorrhoeae. Michael Koomey, Emil C. ... Effects of recA Mutations on Pilus Antigenic Variation and Phase Transitions in Neisseria gonorrhoeae. Michael Koomey, Emil C. ... Effects of recA Mutations on Pilus Antigenic Variation and Phase Transitions in Neisseria gonorrhoeae ...
more infohttps://www.genetics.org/content/117/3/391?ijkey=4d86a204aed9fe4d9590a927cbf66888d689a750&keytype2=tf_ipsecsha

Mosaic VSGs in Trypanosoma brucei antigenic variation  - Enlighten: ThesesMosaic VSGs in Trypanosoma brucei antigenic variation - Enlighten: Theses

parasite, trypanosome, antigenic variation, immune evasion. Subjects:. Q Science , QH Natural history. Q Science , QH Natural ... Hall, James Peter John (2012) Mosaic VSGs in Trypanosoma brucei antigenic variation. PhD thesis, University of Glasgow. ... Segmental gene conversion was therefore found to be both prominent in chronic African trypanosome antigenic variation, and ... trypanosomes-deadly parasites of humans and livestock in tropical Africa-possess a comprehensive system of antigenic variation ...
more infohttp://theses.gla.ac.uk/3796/

Antigenic Variation in Vector-Borne Pathogens - Volume 6, Number 5-October 2000 - Emerging Infectious Diseases journal - CDCAntigenic Variation in Vector-Borne Pathogens - Volume 6, Number 5-October 2000 - Emerging Infectious Diseases journal - CDC

These pathogens use antigenic variation to prolong their circulation in the blood and thus increase the likelihood of ... Antigenic variation poses a challenge in the development of vaccines against vector-borne pathogens. ... bacterial and protozoal vector-borne pathogens have acquired similar genetic mechanisms for successful antigenic variation. ... Antigenic Variation in Vector-Borne Pathogens On This Page What is antigenic variation? Common elements Relapsing Fever ...
more infohttp://wwwnc.cdc.gov/eid/article/6/5/00-0502_article.htm

ASMscience | DNA Recombination Strategies During Antigenic Variation in the African TrypanosomeASMscience | DNA Recombination Strategies During Antigenic Variation in the African Trypanosome

Other work has begun to look at antigenic variation in animal-infective trypanosomes, and we will compare the findings that are ... This chapter will discuss the implications of such VSG diversity for immune evasion by antigenic variation, and will consider ... The essential features of trypanosome antigenic variation have been understood for many years and comprise a dense, protective ... Most studies of trypanosome antigenic variation have focused on T. brucei, the causative agent of human sleeping sickness. ...
more infohttp://www.asmscience.org/content/journal/microbiolspec/10.1128/microbiolspec.MDNA3-0016-2014

Antigenic variation in Lyme disease borreliae by promiscuous recombination of VMP-like sequence cassettes.  - PubMed - NCBIAntigenic variation in Lyme disease borreliae by promiscuous recombination of VMP-like sequence cassettes. - PubMed - NCBI

... resulting in antigenic variation of the expressed lipoprotein. This combinatorial variation could potentially produce millions ... Antigenic variation in Lyme disease borreliae by promiscuous recombination of VMP-like sequence cassettes.. Zhang JR1, Hardham ... system for antigenic variation of relapsing fever organisms. Portions of several of the 15 nonexpressed (silent) vls cassette ... an elaborate genetic system in the Lyme disease spirochete Borrelia burgdorferi that promotes extensive antigenic variation of ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/9108482?dopt=Abstract

The Chemistry of Antigenic Variation in Influenza a Virus Hemagglutinin | Springer for Research & DevelopmentThe Chemistry of Antigenic Variation in Influenza a Virus Hemagglutinin | Springer for Research & Development

... have been used to study the chemistry of antigenic variation within the present subtype of influenza A virus.... ... Single-step antigenic mutants, derived experimentally from the strain A/NT60/68 (H3N2), ... Thus, variation within a hierarchic series of antigenic mutants is associated with minor changes in the primary structure of ... Antigenic Variation Guanidine Hydrochloride Hemagglutinating Activity Sucrose Density Gradient Centrifugation Influenza Virus ...
more infohttps://rd.springer.com/chapter/10.1007/978-3-7091-4130-4_13

Antigenic Variation of Avian Influenza A(H5N6) Viruses, Guangdong Province, China, 2014-2018 - Volume 25, Number 10-October...Antigenic Variation of Avian Influenza A(H5N6) Viruses, Guangdong Province, China, 2014-2018 - Volume 25, Number 10-October...

... revealing antigenic drift and decreased antibody response against the vaccine strain in vaccinated chickens. ... Antigenic Variation of Avian Influenza A(H5N6) Viruses, Guangdong Province, China, 2014-2018 On This Page ... Antigenic Variation of Avian Influenza A(H5N6) Viruses, Guangdong Province, China, 2014-2018. Emerging Infectious Diseases. ... Bai, R., Sikkema, R. S., Li, C., Munnink, B. B., Wu, J., Zou, L....Ke, C. (2019). Antigenic Variation of Avian Influenza A(H5N6 ...
more infohttps://wwwnc.cdc.gov/eid/article/25/10/19-0274

Protein shift and antigenic variation in the S-layer of Campylobacter fetus subsp. venerealis during bovine infection...Protein shift and antigenic variation in the S-layer of Campylobacter fetus subsp. venerealis during bovine infection...

Protein shift and antigenic variation in the S-layer of Campylobacter fetus subsp. venerealis during bovine infection ... Protein shift and antigenic variation in the S-layer of Campylobacter fetus subsp. venerealis during bovine infection ... Protein shift and antigenic variation in the S-layer of Campylobacter fetus subsp. venerealis during bovine infection ... Protein shift and antigenic variation in the S-layer of Campylobacter fetus subsp. venerealis during bovine infection ...
more infohttps://jb.asm.org/content/177/8/1976?ijkey=f01a5eeb623233480933435b4aaf317d53d5b986&keytype2=tf_ipsecsha

Studies on trypanosomatid flagellates with special reference to antigenic variation and kinetoplast DNA  - Enlighten: ThesesStudies on trypanosomatid flagellates with special reference to antigenic variation and kinetoplast DNA - Enlighten: Theses

First, the process of antigenic variation in the African trypanosomes and second the structure and function of the kinetoplast ... Hajduk, Stephen Louis (1980) Studies on trypanosomatid flagellates with special reference to antigenic variation and ... Studies on trypanosomatid flagellates with special reference to antigenic variation and kinetoplast DNA ...
more infohttp://theses.gla.ac.uk/38921/

Antigenic variation | Article about antigenic variation by The Free DictionaryAntigenic variation | Article about antigenic variation by The Free Dictionary

Find out information about antigenic variation. Alteration of an antigen on the surface of a microorganism; may enable a ... pathogenic mocroorganism to evade destruction by the hosts immune system Explanation of antigenic variation ... antigenic variation. Also found in: Dictionary, Thesaurus, Medical, Legal, Wikipedia. antigenic variation. [‚an·tə¦jen·ik ‚ver· ... Antigenic divergence suggested by correlation between antigenic variation and pulsed-field gel electrophoresis profiles of ...
more infohttp://encyclopedia2.thefreedictionary.com/antigenic+variation

British Library EThOS: Investigation of the distribution, antigenic variation and the biological role of phase variation of the...British Library EThOS: Investigation of the distribution, antigenic variation and the biological role of phase variation of the...

Investigation of the distribution, antigenic variation and the biological role of phase variation of the haemoglobin receptors ...
more infohttp://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555487

Impact of sequence diversity in the Moraxella catarrhalis UspA2/UspA2H head domain on vitronectin binding and antigenic...Impact of sequence diversity in the Moraxella catarrhalis UspA2/UspA2H head domain on vitronectin binding and antigenic...

... of sequence diversity in the Moraxella catarrhalis UspA2/UspA2H head domain on vitronectin binding and antigenic variation.. Su ... Vitronectin binding to isolates having UspA2 did not correlate to variation in the NTER2 motifs but occurred in UspA2H ... Vitronectin binding to isolates having UspA2 did not correlate to variation in the NTER2 motifs but occurred in UspA2H ... of sequence diversity in the Moraxella catarrhalis UspA2/UspA2H head domain on vitronectin binding and antigenic variation.}, ...
more infohttps://lup.lub.lu.se/search/publication/c1087449-d485-4f7b-b0f3-c9c24bae50b7

Antigenic variation of foot-and-mouth disease virus serotype A.  - Surrey Research Insight Open AccessAntigenic variation of foot-and-mouth disease virus serotype A. - Surrey Research Insight Open Access

2014) Antigenic variation of foot-and-mouth disease virus serotype A. J Gen Virol, 95 (Pt 2). pp. 384-392. ... Here, we used antigenic cartography to quantify and visualize the antigenic relationships among FMD serotype A viruses, aiming ... Nevertheless, by comparing antigenic distances measured from the antigenic maps with the full capsid (P1) sequence, we ... Furthermore, inherent variation among vaccine sera may impair reproducibility of one-way relationship scores. ...
more infohttp://epubs.surrey.ac.uk/826488/

Browsing  by Subject Antigenic VariationBrowsing by Subject "Antigenic Variation"

World Health Organization. Regional Office for the Western Pacific (Manila : WHO Regional Office for the Western Pacific, 2004) ...
more infohttps://iris.wpro.who.int/browse?authority=Antigenic+Variation&type=mesh

Evaluation of mechanisms that may generate DNA lesions triggering antigenic variation in African trypanosomes  - Enlighten:...Evaluation of mechanisms that may generate DNA lesions triggering antigenic variation in African trypanosomes - Enlighten:...

Antigenic variation by variant surface glycoprotein (VSG) coat switching in African trypanosomes is one of the most elaborate ... Challenging trypanosome antigenic variation paradigms using natural systems. Richard McCulloch. Wellcome Trust (WELLCOTR). ... Evaluation of mechanisms that may generate DNA lesions triggering antigenic variation in African trypanosomes ... Evaluation of mechanisms that may generate DNA lesions triggering antigenic variation in African trypanosomes. PLoS Pathogens, ...
more infohttp://eprints.gla.ac.uk/171013/

Antigenic variation in Schistosoma  - Kingston University Research RepositoryAntigenic variation in 'Schistosoma' - Kingston University Research Repository

Sealey, Katie Lynn (2011) Antigenic variation in Schistosoma. (MSc(R) thesis), Kingston University. ... Results revealed antigenic and structural diversity in these antigens including TSP23 across species and within populations of ... PCR and bioinformatic tools were used to analyse the antigenic and structural diversity of tegumental antigens. ... antigens within and across parasite species to identify genetic changes that could alter the shape of the resultant antigenic ...
more infohttp://eprints.kingston.ac.uk/22525/

Sir2 paralogues cooperate to regulate virulence genes and antigenic variation in Plasmodium falciparum • Research - Institut...Sir2 paralogues cooperate to regulate virulence genes and antigenic variation in Plasmodium falciparum • Research - Institut...

Antigenic variation of PfEMP1 is achieved by in situ switching and mutually exclusive transcription of the var gene family, a ... molecules displayed on the erythrocyte surface are responsible for cytoadherance and undergo antigenic variation in the course ... Antigenic variation of PfEMP1 is achieved by in situ switching and mutually exclusive transcription of the var gene family, a ... Sir2 paralogues cooperate to regulate virulence genes and antigenic variation in Plasmodium falciparum. ...
more infohttps://research.pasteur.fr/en/publication/sir2-paralogues-cooperate-to-regulate-virulence-genes-and-antigenic-variation-in-plasmodium-falciparum/
  • It was discovered in 1984 when it was reported that infected RBCs had unusually large-sized cell membrane proteins, and these proteins had antibody-binding (antigenic) properties. (wikipedia.org)
  • Since the antigenic protein could only be detected in infected cells, they asserted that the protein was produced by the malarial parasite, and not by RBCs. (wikipedia.org)
  • We have identified and characterized an elaborate genetic system in the Lyme disease spirochete Borrelia burgdorferi that promotes extensive antigenic variation of a surface-exposed lipoprotein, VlsE. (nih.gov)
  • Previous studies involving DNA sequence analysis of Borrelia hermsii serotypes, the species endemic to the western United States, have implicated the importance of an upstream homology sequence (UHS) and downstream homology sequence (DHS) for antigenic switching. (grantome.com)
  • Although DNA sequence and statistical analysis has implicated the importance of these DNA elements for vlp/vsp antigenic switching, direct mutational studies providing a mechanistic role for these elements in antigenic variation by any relapsing fever Borrelia species is still lacking. (grantome.com)
  • The proposed work is innovative, because it represents the first time that an antigenic variation system of any relapsing fever Borrelia species has been targeted for mutation. (grantome.com)
  • Intragenic recombination between the single complete pilin gene (expression locus) and multiple, distinct, partial pilin gene copies (silent, storage loci) is thought to account for the generation of pilus antigenic diversity and piliation phase (on-off) changes exhibited by Neisseria gonorrhoeae . (genetics.org)
  • Impact of sequence diversity in the Moraxella catarrhalis UspA2/UspA2H head domain on vitronectin binding and antigenic variation. (lu.se)
  • PCR and bioinformatic tools were used to analyse the antigenic and structural diversity of tegumental antigens. (kingston.ac.uk)
  • Results revealed antigenic and structural diversity in these antigens including TSP23 across species and within populations of 'Schistosoma', and suggest that the definitive host has played a part in positive and adaptive evolution of schistosomes. (kingston.ac.uk)
  • To explore whether these antigenic variations can be translated into protection efficacy difference in vivo, we selected A/chicken/northern China/k0602/2010 (k0602) and A/chicken/Shandong/k0603/2010 (k0603) viruses to evaluate the bivalent inactivated reassortant H5N1/PR8 vaccine Re-4/Re-5 (the HA and NA genes of Re-4 are from a clade 7 virus A/chicken/Shanxi/2/2006). (thefreedictionary.com)
  • One example of antigenic variation occurs in B. hermsii, a cause of tickborne relapsing fever (4) , which has a protein homologous to the OspC protein of B. burgdorferi. (cdc.gov)
  • A 28 kb linear plasmid of B. burgdorferi B31 (lp28-1) was found to contain a vmp-like sequence (vls) locus that closely resembles the variable major protein (vmp) system for antigenic variation of relapsing fever organisms. (nih.gov)
  • Portions of several of the 15 nonexpressed (silent) vls cassette sequences located upstream of vlsE recombined into the central vlsE cassette region during infection of C3H/HeN mice, resulting in antigenic variation of the expressed lipoprotein. (nih.gov)
  • Although this process, referred to as antigenic variation, is the major mechanism of pathogenesis for T. brucei, the dynamics of VSG expression in T. brucei during an infection are poorly understood. (rockefeller.edu)
  • Our results suggest that predicting antigenic difference using genetic sequence alone or by geographical location is not currently reliable. (surrey.ac.uk)
  • Since the antigenic protein could only be detected in infected cells, they asserted that the protein was produced by the malarial parasite, and not by RBCs. (wikipedia.org)
  • Single-step antigenic mutants, derived experimentally from the strain A/NT60/68 (H3N2), have been used to study the chemistry of antigenic variation within the present subtype of influenza A virus. (springer.com)
  • Amino acids 393-395 were essential for binding NVB 97, supporting earlier correlations between antibody blockade escape and carbohydrate binding variation. (nih.gov)
  • Furthermore, inherent variation among vaccine sera may impair reproducibility of one-way relationship scores. (surrey.ac.uk)
  • These mutants will then be used to infect immunocompetent mice to look for a loss of antigenic switching compared to wild-type controls. (grantome.com)
  • Antigenic variation compared to wild-type controls will be monitored after infecting immunocompetent mice. (grantome.com)
  • Our long-term goals are to decipher the mechanistic details of vlp/vsp antigenic variation in B. duttonii, and to expand these findings to the louse-borne variant, B. recurrentis. (grantome.com)
  • falciparum is the var gene family which encodes PfEMP1, a protein that is exported to the 'knob like' binding structures on the surface of infected erythrocytes with a key role in antigenic variation and cytoadherence (12). (thefreedictionary.com)
  • Individual cells either express the phase-variable protein(s) or express one of multiple antigenic forms of the protein. (wikipedia.org)