The type species of LENTIVIRUS and the etiologic agent of AIDS. It is characterized by its cytopathic effect and affinity for the T4-lymphocyte.

A species of LENTIVIRUS, subgenus feline lentiviruses (LENTIVIRUSES, FELINE) isolated from cats with a chronic wasting syndrome, presumed to be immune deficiency. There are 3 strains: Petaluma (FIP-P), Oma (FIP-O) and Puma lentivirus (PLV). There is no antigenic relationship between FIV and HIV, nor does FIV grow in human T-cells.

Species of the genus LENTIVIRUS, subgenus primate immunodeficiency viruses (IMMUNODEFICIENCY VIRUSES, PRIMATE), that induces acquired immunodeficiency syndrome in monkeys and apes (SAIDS). The genetic organization of SIV is virtually identical to HIV.

Includes the spectrum of human immunodeficiency virus infections that range from asymptomatic seropositivity, thru AIDS-related complex (ARC), to acquired immunodeficiency syndrome (AIDS).

Acquired defect of cellular immunity that occurs in cats infected with feline immunodeficiency virus (FIV) and in some cats infected with feline leukemia virus (FeLV).

An acquired defect of cellular immunity associated with infection by the human immunodeficiency virus (HIV), a CD4-positive T-lymphocyte count under 200 cells/microliter or less than 14% of total lymphocytes, and increased susceptibility to opportunistic infections and malignant neoplasms. Clinical manifestations also include emaciation (wasting) and dementia. These elements reflect criteria for AIDS as defined by the CDC in 1993.

The process of intracellular viral multiplication, consisting of the synthesis of PROTEINS; NUCLEIC ACIDS; and sometimes LIPIDS, and their assembly into a new infectious particle.

A species of GAMMARETROVIRUS causing leukemia, lymphosarcoma, immune deficiency, or other degenerative diseases in cats. Several cellular oncogenes confer on FeLV the ability to induce sarcomas (see also SARCOMA VIRUSES, FELINE).

Human immunodeficiency virus. A non-taxonomic and historical term referring to any of two species, specifically HIV-1 and/or HIV-2. Prior to 1986, this was called human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). From 1986-1990, it was an official species called HIV. Since 1991, HIV was no longer considered an official species name; the two species were designated HIV-1 and HIV-2.

Acquired defect of cellular immunity that occurs naturally in macaques infected with SRV serotypes, experimentally in monkeys inoculated with SRV or MASON-PFIZER MONKEY VIRUS; (MPMV), or in monkeys infected with SIMIAN IMMUNODEFICIENCY VIRUS.

The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)

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.

Proteins encoded by the TAT GENES of the HUMAN IMMUNODEFICIENCY VIRUS.

Ribonucleic acid that makes up the genetic material of viruses.

External envelope protein of the human immunodeficiency virus which is encoded by the HIV env gene. It has a molecular weight of 120 kDa and contains numerous glycosylation sites. Gp120 binds to cells expressing CD4 cell-surface antigens, most notably T4-lymphocytes and monocytes/macrophages. Gp120 has been shown to interfere with the normal function of CD4 and is at least partly responsible for the cytopathic effect of HIV.

Proteins coded by the retroviral gag gene. The products are usually synthesized as protein precursors or POLYPROTEINS, which are then cleaved by viral proteases to yield the final products. Many of the final products are associated with the nucleoprotein core of the virion. gag is short for group-specific antigen.

An HIV species related to HIV-1 but carrying different antigenic components and with differing nucleic acid composition. It shares serologic reactivity and sequence homology with the simian Lentivirus SIMIAN IMMUNODEFICIENCY VIRUS and infects only T4-lymphocytes expressing the CD4 phenotypic marker.

Diseases of the domestic cat (Felis catus or F. domesticus). This term does not include diseases of the so-called big cats such as CHEETAHS; LIONS; tigers, cougars, panthers, leopards, and other Felidae for which the heading CARNIVORA is used.

Antibodies reactive with HIV ANTIGENS.

Agents used to treat AIDS and/or stop the spread of the HIV infection. These do not include drugs used to treat symptoms or opportunistic infections associated with AIDS.

Retroviral proteins, often glycosylated, coded by the envelope (env) gene. They are usually synthesized as protein precursors (POLYPROTEINS) and later cleaved into the final viral envelope glycoproteins by a viral protease.

Established cell cultures that have the potential to propagate indefinitely.

A species of the genus VESIVIRUS infecting cats. Transmission occurs via air and mechanical contact.

Deoxyribonucleic acid that makes up the genetic material of viruses.

A reverse transcriptase encoded by the POL GENE of HIV. It is a heterodimer of 66 kDa and 51 kDa subunits that are derived from a common precursor protein. The heterodimer also includes an RNAse H activity (RIBONUCLEASE H, HUMAN IMMUNODEFICIENCY VIRUS) that plays an essential role the viral replication process.

A species of CORONAVIRUS infecting cats of all ages and commonly found in catteries and zoos. Cats are often found carrying the virus but only a small proportion develop disease. Feline coronavirus and Feline infectious peritonitis virus (FIPV) are virtually the same virus in genetic and antigenetic terms, and are morphologically indistinguishable. Since they only differ in their disease potential (with FIPV causing a more serious illness), they are considered biotypes of each other.

A major core protein of the human immunodeficiency virus encoded by the HIV gag gene. HIV-seropositive individuals mount a significant immune response to p24 and thus detection of antibodies to p24 is one basis for determining HIV infection by ELISA and Western blot assays. The protein is also being investigated as a potential HIV immunogen in vaccines.

Proteins encoded by the NEF GENES of the HUMAN IMMUNODEFICIENCY VIRUS.

Proteins encoded by the GAG GENE of the HUMAN IMMUNODEFICIENCY VIRUS.

55-kDa antigens found on HELPER-INDUCER T-LYMPHOCYTES and on a variety of other immune cell types. CD4 antigens are members of the immunoglobulin supergene family and are implicated as associative recognition elements in MAJOR HISTOCOMPATIBILITY COMPLEX class II-restricted immune responses. On T-lymphocytes they define the helper/inducer subset. CD4 antigens also serve as INTERLEUKIN-15 receptors and bind to the HIV receptors, binding directly to the HIV ENVELOPE PROTEIN GP120.

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.

The quantity of measurable virus in a body fluid. Change in viral load, measured in plasma, is sometimes used as a SURROGATE MARKER in disease progression.

Development of neutralizing antibodies in individuals who have been exposed to the human immunodeficiency virus (HIV/HTLV-III/LAV).

A species of the genus MACACA inhabiting India, China, and other parts of Asia. The species is used extensively in biomedical research and adapts very well to living with humans.

A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by an azido group. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is a potent inhibitor of HIV replication, acting as a chain-terminator of viral DNA during reverse transcription. It improves immunologic function, partially reverses the HIV-induced neurological dysfunction, and improves certain other clinical abnormalities associated with AIDS. Its principal toxic effect is dose-dependent suppression of bone marrow, resulting in anemia and leukopenia.

Virus diseases caused by the Lentivirus genus. They are multi-organ diseases characterized by long incubation periods and persistent infection.

The number of CD4-POSITIVE T-LYMPHOCYTES per unit volume of BLOOD. Determination requires the use of a fluorescence-activated flow cytometer.

DNA sequences that form the coding region for the viral envelope (env) proteins in retroviruses. The env genes contain a cis-acting RNA target sequence for the rev protein (= GENE PRODUCTS, REV), termed the rev-responsive element (RRE).

Inhibitors of reverse transcriptase (RNA-DIRECTED DNA POLYMERASE), an enzyme that synthesizes DNA on an RNA template.

Regulatory sequences important for viral replication that are located on each end of the HIV genome. The LTR includes the HIV ENHANCER, promoter, and other sequences. Specific regions in the LTR include the negative regulatory element (NRE), NF-kappa B binding sites , Sp1 binding sites, TATA BOX, and trans-acting responsive element (TAR). The binding of both cellular and viral proteins to these regions regulates HIV transcription.

Proteins encoded by the REV GENES of the HUMAN IMMUNODEFICIENCY VIRUS.

Antigens associated with specific proteins of the human adult T-cell immunodeficiency virus (HIV); also called HTLV-III-associated and lymphadenopathy-associated virus (LAV) antigens.

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).

Trans-acting transcription factors produced by retroviruses such as HIV. They are nuclear proteins whose expression is required for viral replication. The tat protein stimulates LONG TERMINAL REPEAT-driven RNA synthesis for both viral regulatory and viral structural proteins. tat stands for trans-activation of transcription.

The type species of ORTHOPOXVIRUS, related to COWPOX VIRUS, but whose true origin is unknown. It has been used as a live vaccine against SMALLPOX. It is also used as a vector for inserting foreign DNA into animals. Rabbitpox virus is a subspecies of VACCINIA VIRUS.

The infective system of a virus, composed of the viral genome, a protein core, and a protein coat called a capsid, which may be naked or enclosed in a lipoprotein envelope called the peplos.

Transmembrane envelope protein of the HUMAN IMMUNODEFICIENCY VIRUS which is encoded by the HIV env gene. It has a molecular weight of 41,000 and is glycosylated. The N-terminal part of gp41 is thought to be involved in CELL FUSION with the CD4 ANTIGENS of T4 LYMPHOCYTES, leading to syncytial formation. Gp41 is one of the most common HIV antigens detected by IMMUNOBLOTTING.

Specific molecular components of the cell capable of recognizing and interacting with a virus, and which, after binding it, are capable of generating some signal that initiates the chain of events leading to the biological response.

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

A critical subpopulation of T-lymphocytes involved in the induction of most immunological functions. The HIV virus has selective tropism for the T4 cell which expresses the CD4 phenotypic marker, a receptor for HIV. In fact, the key element in the profound immunosuppression seen in HIV infection is the depletion of this subset of T-lymphocytes.

The assembly of VIRAL STRUCTURAL PROTEINS and nucleic acid (VIRAL DNA or VIRAL RNA) to form a VIRUS PARTICLE.

Duplex DNA sequences in eukaryotic chromosomes, corresponding to the genome of a virus, that are transmitted from one cell generation to the next without causing lysis of the host. Proviruses are often associated with neoplastic cell transformation and are key features of retrovirus biology.

An enzyme that synthesizes DNA on an RNA template. It is encoded by the pol gene of retroviruses and by certain retrovirus-like elements. EC 2.7.7.49.

Viruses whose genetic material is RNA.

CCR receptors with specificity for CHEMOKINE CCL3; CHEMOKINE CCL4; and CHEMOKINE CCL5. They are expressed at high levels in T-LYMPHOCYTES; B-LYMPHOCYTES; MACROPHAGES; MAST CELLS; and NK CELLS. The CCR5 receptor is used by the HUMAN IMMUNODEFICIENCY VIRUS to infect cells.

Proteins synthesized by HUMAN IMMUNODEFICIENCY VIRUSES such as the HIV-1 and HIV-2.

Vaccines or candidate vaccines containing inactivated HIV or some of its component antigens and designed to prevent or treat AIDS. Some vaccines containing antigens are recombinantly produced.

Enzyme of the human immunodeficiency virus that is required for post-translational cleavage of gag and gag-pol precursor polyproteins into functional products needed for viral assembly. HIV protease is an aspartic protease encoded by the amino terminus of the pol gene.

DNA sequences that form the coding region for proteins associated with the viral core in retroviruses. gag is short for group-specific antigen.

Proteins encoded by the VPR GENES of the HUMAN IMMUNODEFICIENCY VIRUS.

Products of the retroviral NEF GENE. They play a role as accessory proteins that influence the rate of viral infectivity and the destruction of the host immune system. nef gene products were originally found as factors that trans-suppress viral replication and function as negative regulators of transcription. nef stands for negative factor.

Inhibitors of HIV PROTEASE, an enzyme required for production of proteins needed for viral assembly.

An envelope protein of the human immunodeficiency virus that is encoded by the HIV env gene. It has a molecular weight of 160,000 kDa and contains numerous glycosylation sites. It serves as a precursor for both the HIV ENVELOPE PROTEIN GP120 and the HIV ENVELOPE PROTEIN GP41.

Species of GAMMARETROVIRUS isolated from fibrosarcoma in cats. The viruses are actually recombinant feline leukemia viruses (FeLV) where part of the genome has been replaced by cellular oncogenes. It is unique to individuals and not transmitted naturally to other cats. FeSVs are replication defective and require FeLV to reproduce.

The presence of viruses in the blood.

Opportunistic infections found in patients who test positive for human immunodeficiency virus (HIV). The most common include PNEUMOCYSTIS PNEUMONIA, Kaposi's sarcoma, cryptosporidiosis, herpes simplex, toxoplasmosis, cryptococcosis, and infections with Mycobacterium avium complex, Microsporidium, and Cytomegalovirus.

Agents used in the prophylaxis or therapy of VIRUS DISEASES. Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly.

A highly contagious DNA virus infection of the cat family, characterized by fever, enteritis and bone marrow changes. It is also called feline ataxia, feline agranulocytosis, feline infectious enteritis, cat fever, cat plague, and show fever. It is caused by FELINE PANLEUKOPENIA VIRUS or the closely related MINK ENTERITIS VIRUS or CANINE PARVOVIRUS.

Mature LYMPHOCYTES and MONOCYTES transported by the blood to the body's extravascular space. They are morphologically distinguishable from mature granulocytic leukocytes by their large, non-lobed nuclei and lack of coarse, heavily stained cytoplasmic granules.

Group of rare congenital disorders characterized by impairment of both humoral and cell-mediated immunity, leukopenia, and low or absent antibody levels. It is inherited as an X-linked or autosomal recessive defect. Mutations occurring in many different genes cause human Severe Combined Immunodeficiency (SCID).

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.

Proteins encoded by the ENV GENE of the HUMAN IMMUNODEFICIENCY VIRUS.

Insertion of viral DNA into host-cell DNA. This includes integration of phage DNA into bacterial DNA; (LYSOGENY); to form a PROPHAGE or integration of retroviral DNA into cellular DNA to form a PROVIRUS.

CXCR receptors with specificity for CXCL12 CHEMOKINE. The receptors may play a role in HEMATOPOIESIS regulation and can also function as coreceptors for the HUMAN IMMUNODEFICIENCY VIRUS.

The expelling of virus particles from the body. Important routes include the respiratory tract, genital tract, and intestinal tract. Virus shedding is an important means of vertical transmission (INFECTIOUS DISEASE TRANSMISSION, VERTICAL).

The type species of LENTIVIRUS, subgenus bovine lentiviruses (LENTIVIRUSES, BOVINE), found in cattle and causing lymphadenopathy, LYMPHOCYTOSIS, central nervous system lesions, progressive weakness, and emaciation. It has immunological cross-reactivity with other lentiviruses including HIV.

Any of the processes by which cytoplasmic factors influence the differential control of gene action in viruses.

Process of growing viruses in live animals, plants, or cultured cells.

Immune status consisting of non-production of HIV antibodies, as determined by various serological tests.

Trans-acting nuclear proteins whose functional expression are required for retroviral replication. Specifically, the rev gene products are required for processing and translation of the gag and env mRNAs, and thus rev regulates the expression of the viral structural proteins. rev can also regulate viral regulatory proteins. A cis-acting antirepression sequence (CAR) in env, also known as the rev-responsive element (RRE), is responsive to the rev gene product. rev is short for regulator of virion.

Common coronavirus infection of cats caused by the feline infectious peritonitis virus (CORONAVIRUS, FELINE). The disease is characterized by a long incubation period, fever, depression, loss of appetite, wasting, and progressive abdominal enlargement. Infection of cells of the monocyte-macrophage lineage appears to be essential in FIP pathogenesis.

Immunoglobulins produced in response to VIRAL ANTIGENS.

The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.

Proteins encoded by the VIF GENES of the HUMAN IMMUNODEFICIENCY VIRUS.

A species of the genus MACACA which inhabits Malaya, Sumatra, and Borneo. It is one of the most arboreal species of Macaca. The tail is short and untwisted.

Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.

A species of PARVOVIRUS infecting cats with a highly contagious enteric disease. Host range variants include mink enteritis virus, canine parvovirus (PARVOVIRUS, CANINE), and raccoon parvovirus. After infecting their new hosts, many of these viruses have further evolved and are now considered distinct species.

Drug regimens, for patients with HIV INFECTIONS, that aggressively suppress HIV replication. The regimens usually involve administration of three or more different drugs including a protease inhibitor.

The ability of viruses to resist or to become tolerant to chemotherapeutic agents or antiviral agents. This resistance is acquired through gene mutation.

The functional hereditary units of VIRUSES.

Viruses which lack a complete genome so that they cannot completely replicate or cannot form a protein coat. Some are host-dependent defectives, meaning they can replicate only in cell systems which provide the particular genetic function which they lack. Others, called SATELLITE VIRUSES, are able to replicate only when their genetic defect is complemented by a helper virus.

The relationships of groups of organisms as reflected by their genetic makeup.

Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.

A neoplastic disease of cats frequently associated with feline leukemia virus infection.

Multinucleated masses produced by the fusion of many cells; often associated with viral infections. In AIDS, they are induced when the envelope glycoprotein of the HIV virus binds to the CD4 antigen of uninfected neighboring T4 cells. The resulting syncytium leads to cell death and thus may account for the cytopathic effect of the virus.

DNA sequences that form the coding region for a protein that down-regulates the expression of human immunodeficiency virus (HIV). nef is short for negative factor.

DNA sequences that form the coding region for retroviral enzymes including reverse transcriptase, protease, and endonuclease/integrase. "pol" is short for polymerase, the enzyme class of reverse transcriptase.

Trans-acting proteins which accelerate retroviral virus replication. The vpr proteins act in trans to increase the levels of specified proteins. vpr is short for viral protein R, where R is undefined.

A general term for diseases produced by viruses.

Substances elaborated by viruses that have antigenic activity.

Proteins from the family Retroviridae. The most frequently encountered member of this family is the Rous sarcoma virus protein.

Proteins found in any species of virus.

DNA sequences that form the coding region for the protein responsible for trans-activation of transcription (tat) in human immunodeficiency virus (HIV).

Cellular receptors that bind the human immunodeficiency virus that causes AIDS. Included are CD4 ANTIGENS, found on T4 lymphocytes, and monocytes/macrophages, which bind to the HIV ENVELOPE PROTEIN GP120.

Vaccines or candidate vaccines designed to prevent SAIDS; (SIMIAN ACQUIRED IMMUNODEFICIENCY SYNDROME); and containing inactivated SIMIAN IMMUNODEFICIENCY VIRUS or type D retroviruses or some of their component antigens.

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.

DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition.

The transmission of infectious disease or pathogens from one generation to another. It includes transmission in utero or intrapartum by exposure to blood and secretions, and postpartum exposure via breastfeeding.

Visible morphologic changes in cells infected with viruses. It includes shutdown of cellular RNA and protein synthesis, cell fusion, release of lysosomal enzymes, changes in cell membrane permeability, diffuse changes in intracellular structures, presence of viral inclusion bodies, and chromosomal aberrations. It excludes malignant transformation, which is CELL TRANSFORMATION, VIRAL. Viral cytopathogenic effects provide a valuable method for identifying and classifying the infecting viruses.

DNA sequences that form the coding region for a protein that regulates the expression of the viral structural and regulatory proteins in human immunodeficiency virus (HIV). rev is short for regulator of virion.

A broad category of viral proteins that play indirect roles in the biological processes and activities of viruses. Included here are proteins that either regulate the expression of viral genes or are involved in modifying host cell functions. Many of the proteins in this category serve multiple functions.

Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.

Retroviral proteins coded by the pol gene. They are usually synthesized as a protein precursor (POLYPROTEINS) and later cleaved into final products that include reverse transcriptase, endonuclease/integrase, and viral protease. Sometimes they are synthesized as a gag-pol fusion protein (FUSION PROTEINS, GAG-POL). pol is short for polymerase, the enzyme class of reverse transcriptase.

A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by a hydrogen. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. Didanosine is a potent inhibitor of HIV replication, acting as a chain-terminator of viral DNA by binding to reverse transcriptase; ddI is then metabolized to dideoxyadenosine triphosphate, its putative active metabolite.

The mechanism by which latent viruses, such as genetically transmitted tumor viruses (PROVIRUSES) or PROPHAGES of lysogenic bacteria, are induced to replicate and then released as infectious viruses. It may be effected by various endogenous and exogenous stimuli, including B-cell LIPOPOLYSACCHARIDES, glucocorticoid hormones, halogenated pyrimidines, IONIZING RADIATION, ultraviolet light, and superinfecting viruses.

Heterogeneous group of immunodeficiency syndromes characterized by hypogammaglobulinemia of most isotypes, variable B-cell defects, and the presence of recurrent bacterial infections.

A species of POLYOMAVIRUS originally isolated from Rhesus monkey kidney tissue. It produces malignancy in human and newborn hamster kidney cell cultures.

A genus of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, consisting of 16 species inhabiting forests of Africa, Asia, and the islands of Borneo, Philippines, and Celebes.

Syndromes in which there is a deficiency or defect in the mechanisms of immunity, either cellular or humoral.

Retrovirally encoded accessary proteins that play an essential role VIRUS REPLICATION. They are found in the cytoplasm of host cells and associate with a variety of host cell proteins. Vif stands for "virion infectivity factor".

A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by a hydrogen. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is a potent inhibitor of HIV replication at low concentrations, acting as a chain-terminator of viral DNA by binding to reverse transcriptase. Its principal toxic side effect is axonal degeneration resulting in peripheral neuropathy.

A critical subpopulation of regulatory T-lymphocytes involved in MHC Class I-restricted interactions. They include both cytotoxic T-lymphocytes (T-LYMPHOCYTES, CYTOTOXIC) and CD8+ suppressor T-lymphocytes.

A prodromal phase of infection with the human immunodeficiency virus (HIV). Laboratory criteria separating AIDS-related complex (ARC) from AIDS include elevated or hyperactive B-cell humoral immune responses, compared to depressed or normal antibody reactivity in AIDS; follicular or mixed hyperplasia in ARC lymph nodes, leading to lymphocyte degeneration and depletion more typical of AIDS; evolving succession of histopathological lesions such as localization of Kaposi's sarcoma, signaling the transition to the full-blown AIDS.

A species of CERCOPITHECUS containing three subspecies: C. tantalus, C. pygerythrus, and C. sabeus. They are found in the forests and savannah of Africa. The African green monkey (C. pygerythrus) is the natural host of SIMIAN IMMUNODEFICIENCY VIRUS and is used in AIDS research.

Viruses whose nucleic acid is DNA.

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.

Polyprotein products of a fused portion of retroviral mRNA containing the gag and pol genes. The polyprotein is synthesized only five percent of the time since pol is out of frame with gag, and is generated by ribosomal frameshifting.

Proteins prepared by recombinant DNA technology.

A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.

Viruses parasitic on plants higher than bacteria.

Sites on an antigen that interact with specific antibodies.

The ability of a pathogenic virus to lie dormant within a cell (latent infection). In eukaryotes, subsequent activation and viral replication is thought to be caused by extracellular stimulation of cellular transcription factors. Latency in bacteriophage is maintained by the expression of virally encoded repressors.

The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.

The type species of MORBILLIVIRUS and the cause of the highly infectious human disease MEASLES, which affects mostly children.

Genotypic differences observed among individuals in a population.

Elements of limited time intervals, contributing to particular results or situations.

The type species of ALPHAVIRUS normally transmitted to birds by CULEX mosquitoes in Egypt, South Africa, India, Malaya, the Philippines, and Australia. It may be associated with fever in humans. Serotypes (differing by less than 17% in nucleotide sequence) include Babanki, Kyzylagach, and Ockelbo viruses.

Enzyme of the HUMAN IMMUNODEFICIENCY VIRUS that is required to integrate viral DNA into cellular DNA in the nucleus of a host cell. HIV integrase is a DNA nucleotidyltransferase encoded by the pol gene.

Antibodies produced by a single clone of cells.

The type species of the genus ORTHOHEPADNAVIRUS which causes human HEPATITIS B and is also apparently a causal agent in human HEPATOCELLULAR CARCINOMA. The Dane particle is an intact hepatitis virion, named after its discoverer. Non-infectious spherical and tubular particles are also seen in the serum.

A subtype of INFLUENZA A VIRUS with the surface proteins hemagglutinin 1 and neuraminidase 1. The H1N1 subtype was responsible for the Spanish flu pandemic of 1918.

The type species of LYSSAVIRUS causing rabies in humans and other animals. Transmission is mostly by animal bites through saliva. The virus is neurotropic multiplying in neurons and myotubes of vertebrates.

The phosphate esters of DIDEOXYNUCLEOSIDES.

The outer protein protective shell of a virus, which protects the viral nucleic acid.

The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.

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.

A potent and specific HIV protease inhibitor that appears to have good oral bioavailability.

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.

INFLAMMATION of the LIVER in humans caused by HEPATITIS C VIRUS, a single-stranded RNA virus. Its incubation period is 30-90 days. Hepatitis C is transmitted primarily by contaminated blood parenterally, and is often associated with transfusion and intravenous drug abuse. However, in a significant number of cases, the source of hepatitis C infection is unknown.

Family of RNA viruses that infects birds and mammals and encodes the enzyme reverse transcriptase. The family contains seven genera: DELTARETROVIRUS; LENTIVIRUS; RETROVIRUSES TYPE B, MAMMALIAN; ALPHARETROVIRUS; GAMMARETROVIRUS; RETROVIRUSES TYPE D; and SPUMAVIRUS. A key feature of retrovirus biology is the synthesis of a DNA copy of the genome which is integrated into cellular DNA. After integration it is sometimes not expressed but maintained in a latent state (PROVIRUSES).

Protein precursors, also known as proproteins or prohormones, are inactive forms of proteins that undergo post-translational modification, such as cleavage, to produce the active functional protein or peptide hormone.

A subtype of INFLUENZA A VIRUS comprised of the surface proteins hemagglutinin 5 and neuraminidase 1. The H5N1 subtype, frequently referred to as the bird flu virus, is endemic in wild birds and very contagious among both domestic (POULTRY) and wild birds. It does not usually infect humans, but some cases have been reported.

The parts of a macromolecule that directly participate in its specific combination with another molecule.

Carbon-containing phosphonic acid compounds. Included under this heading are compounds that have carbon bound to either OXYGEN atom or the PHOSPHOROUS atom of the (P=O)O2 structure.

A neurologic condition associated with the ACQUIRED IMMUNODEFICIENCY SYNDROME and characterized by impaired concentration and memory, slowness of hand movements, ATAXIA, incontinence, apathy, and gait difficulties associated with HIV-1 viral infection of the central nervous system. Pathologic examination of the brain reveals white matter rarefaction, perivascular infiltrates of lymphocytes, foamy macrophages, and multinucleated giant cells. (From Adams et al., Principles of Neurology, 6th ed, pp760-1; N Engl J Med, 1995 Apr 6;332(14):934-40)

The binding of virus particles to receptors on the host cell surface. For enveloped viruses, the virion ligand is usually a surface glycoprotein as is the cellular receptor. For non-enveloped viruses, the virus CAPSID serves as the ligand.

Infections produced by oncogenic viruses. The infections caused by DNA viruses are less numerous but more diverse than those caused by the RNA oncogenic viruses.

The genital canal in the female, extending from the UTERUS to the VULVA. (Stedman, 25th ed)

Virus diseases caused by the RETROVIRIDAE.

Immunized T-lymphocytes which can directly destroy appropriate target cells. These cytotoxic lymphocytes may be generated in vitro in mixed lymphocyte cultures (MLC), in vivo during a graft-versus-host (GVH) reaction, or after immunization with an allograft, tumor cell or virally transformed or chemically modified target cell. The lytic phenomenon is sometimes referred to as cell-mediated lympholysis (CML). These CD8-positive cells are distinct from NATURAL KILLER CELLS and NATURAL KILLER T-CELLS. There are two effector phenotypes: TC1 and TC2.

Fusion of somatic cells in vitro or in vivo, which results in somatic cell hybridization.

Ratio of T-LYMPHOCYTES that express the CD4 ANTIGEN to those that express the CD8 ANTIGEN. This value is commonly assessed in the diagnosis and staging of diseases affecting the IMMUNE SYSTEM including HIV INFECTIONS.

The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)

The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.

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.

Nucleosides that have two hydroxy groups removed from the sugar moiety. The majority of these compounds have broad-spectrum antiretroviral activity due to their action as antimetabolites. The nucleosides are phosphorylated intracellularly to their 5'-triphosphates and act as chain-terminating inhibitors of viral reverse transcription.

A genus in the family FELIDAE comprising one species, Puma concolor. It is a large, long-tailed, feline of uniform color. The names puma, cougar, and mountain lion are used interchangeably for this species. There are more than 20 subspecies.

Proteins encoded by the POL GENE of the HUMAN IMMUNODEFICIENCY VIRUS.

Method for measuring viral infectivity and multiplication in CULTURED CELLS. Clear lysed areas or plaques develop as the VIRAL PARTICLES are released from the infected cells during incubation. With some VIRUSES, the cells are killed by a cytopathic effect; with others, the infected cells are not killed but can be detected by their hemadsorptive ability. Sometimes the plaque cells contain VIRAL ANTIGENS which can be measured by IMMUNOFLUORESCENCE.

A reverse transcriptase inhibitor and ZALCITABINE analog in which a sulfur atom replaces the 3' carbon of the pentose ring. It is used to treat HIV disease.

The rate dynamics in chemical or physical systems.

Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.

The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes.

Small synthetic peptides that mimic surface antigens of pathogens and are immunogenic, or vaccines manufactured with the aid of recombinant DNA techniques. The latter vaccines may also be whole viruses whose nucleic acids have been modified.

Inactivation of viruses by non-immune related techniques. They include extremes of pH, HEAT treatment, ultraviolet radiation, IONIZING RADIATION; DESICCATION; ANTISEPTICS; DISINFECTANTS; organic solvents, and DETERGENTS.

A subtype of INFLUENZA A VIRUS comprised of the surface proteins hemagglutinin 3 and neuraminidase 2. The H3N2 subtype was responsible for the Hong Kong flu pandemic of 1968.

Viruses that produce tumors.

The type species of VESICULOVIRUS causing a disease symptomatically similar to FOOT-AND-MOUTH DISEASE in cattle, horses, and pigs. It may be transmitted to other species including humans, where it causes influenza-like symptoms.

Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.

Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.

Morphologic alteration of small B LYMPHOCYTES or T LYMPHOCYTES in culture into large blast-like cells able to synthesize DNA and RNA and to divide mitotically. It is induced by INTERLEUKINS; MITOGENS such as PHYTOHEMAGGLUTININS, and by specific ANTIGENS. It may also occur in vivo as in GRAFT REJECTION.

The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.

White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.

The co-occurrence of pregnancy and an INFECTION. The infection may precede or follow FERTILIZATION.

A species of FLAVIVIRUS, one of the Japanese encephalitis virus group (ENCEPHALITIS VIRUSES, JAPANESE). It can infect birds and mammals. In humans, it is seen most frequently in Africa, Asia, and Europe presenting as a silent infection or undifferentiated fever (WEST NILE FEVER). The virus appeared in North America for the first time in 1999. It is transmitted mainly by CULEX spp mosquitoes which feed primarily on birds, but it can also be carried by the Asian Tiger mosquito, AEDES albopictus, which feeds mainly on mammals.

The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.

Proteins that form the CAPSID of VIRUSES.

Immunologic tests for identification of HIV (HTLV-III/LAV) antibodies. They include assays for HIV SEROPOSITIVITY and HIV SERONEGATIVITY that have been developed for screening persons carrying the viral antibody from patients with overt symptoms of AIDS or AIDS-RELATED COMPLEX.

Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.

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.

DNA sequences that form the coding region for a trans-activator protein that specifies rapid growth in human immunodeficiency virus (HIV). vpr is short for viral protein R, where R is undefined.

An HIV protease inhibitor which acts as an analog of an HIV protease cleavage site. It is a highly specific inhibitor of HIV-1 and HIV-2 proteases, and also inhibits CYTOCHROME P-450 CYP3A.

The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.

A group of viruses in the PNEUMOVIRUS genus causing respiratory infections in various mammals. Humans and cattle are most affected but infections in goats and sheep have also been reported.

The sexual attraction or relationship between members of the same SEX.

The complete genetic complement contained in a DNA or RNA molecule in a virus.

A CELL LINE derived from the kidney of the African green (vervet) monkey, (CERCOPITHECUS AETHIOPS) used primarily in virus replication studies and plaque assays.

Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.

A strain of Murine leukemia virus (LEUKEMIA VIRUS, MURINE) arising during the propagation of S37 mouse sarcoma, and causing lymphoid leukemia in mice. It also infects rats and newborn hamsters. It is apparently transmitted to embryos in utero and to newborns through mother's milk.

The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).

A dideoxynucleoside analog that inhibits reverse transcriptase and has in vitro activity against HIV.

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.