Hepatitis B: INFLAMMATION of the LIVER in humans caused by a member of the ORTHOHEPADNAVIRUS genus, HEPATITIS B VIRUS. It is primarily transmitted by parenteral exposure, such as transfusion of contaminated blood or blood products, but can also be transmitted via sexual or intimate personal contact.Hepatitis C: 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.Hepatitis A: INFLAMMATION of the LIVER in humans caused by a member of the HEPATOVIRUS genus, HUMAN HEPATITIS A VIRUS. It can be transmitted through fecal contamination of food or water.Hepatitis B virus: 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.Hepatitis B Surface Antigens: Those hepatitis B antigens found on the surface of the Dane particle and on the 20 nm spherical and tubular particles. Several subspecificities of the surface antigen are known. These were formerly called the Australia antigen.Hepatitis: INFLAMMATION of the LIVER.Hepatitis C, Chronic: INFLAMMATION of the LIVER in humans that is caused by HEPATITIS C VIRUS lasting six months or more. Chronic hepatitis C can lead to LIVER CIRRHOSIS.Hepatitis B, Chronic: INFLAMMATION of the LIVER in humans caused by HEPATITIS B VIRUS lasting six months or more. It is primarily transmitted by parenteral exposure, such as transfusion of contaminated blood or blood products, but can also be transmitted via sexual or intimate personal contact.Hepatitis, Viral, Human: INFLAMMATION of the LIVER in humans due to infection by VIRUSES. There are several significant types of human viral hepatitis with infection caused by enteric-transmission (HEPATITIS A; HEPATITIS E) or blood transfusion (HEPATITIS B; HEPATITIS C; and HEPATITIS D).Hepatitis A virus: A species in the genus HEPATOVIRUS containing one serotype and two strains: HUMAN HEPATITIS A VIRUS and Simian hepatitis A virus causing hepatitis in humans (HEPATITIS A) and primates, respectively.Hepatitis B Vaccines: Vaccines or candidate vaccines containing inactivated hepatitis B or some of its component antigens and designed to prevent hepatitis B. Some vaccines may be recombinantly produced.Hepatitis B Antibodies: Antibodies to the HEPATITIS B ANTIGENS, including antibodies to the surface (Australia) and core of the Dane particle and those to the "e" antigens.Hepatitis, Chronic: INFLAMMATION of the LIVER with ongoing hepatocellular injury for 6 months or more, characterized by NECROSIS of HEPATOCYTES and inflammatory cell (LEUKOCYTES) infiltration. Chronic hepatitis can be caused by viruses, medications, autoimmune diseases, and other unknown factors.Hepatitis B Core Antigens: The hepatitis B antigen within the core of the Dane particle, the infectious hepatitis virion.Hepatitis A Vaccines: Vaccines or candidate vaccines used to prevent infection with hepatitis A virus (HEPATOVIRUS).Hepatitis Antibodies: Immunoglobulins raised by any form of viral hepatitis; some of these antibodies are used to diagnose the specific kind of hepatitis.Hepacivirus: A genus of FLAVIVIRIDAE causing parenterally-transmitted HEPATITIS C which is associated with transfusions and drug abuse. Hepatitis C virus is the type species.Hepatitis B e Antigens: A closely related group of antigens found in the plasma only during the infective phase of hepatitis B or in virulent chronic hepatitis B, probably indicating active virus replication; there are three subtypes which may exist in a complex with immunoglobulins G.Hepatitis B Antigens: Antigens of the virion of the HEPATITIS B VIRUS or the Dane particle, its surface (HEPATITIS B SURFACE ANTIGENS), core (HEPATITIS B CORE ANTIGENS), and other associated antigens, including the HEPATITIS B E ANTIGENS.Hepatitis E: Acute INFLAMMATION of the LIVER in humans; caused by HEPATITIS E VIRUS, a non-enveloped single-stranded RNA virus. Similar to HEPATITIS A, its incubation period is 15-60 days and is enterically transmitted, usually by fecal-oral transmission.Hepatitis C Antibodies: Antibodies to the HEPATITIS C ANTIGENS including antibodies to envelope, core, and non-structural proteins.Hepatitis E virus: A positive-stranded RNA virus species in the genus HEPEVIRUS, causing enterically-transmitted non-A, non-B hepatitis (HEPATITIS E).Hepatitis A Antibodies: Antibodies to the HEPATITIS A ANTIGENS including antibodies to envelope, core, and non-structural proteins.Hepatitis, Viral, Animal: INFLAMMATION of the LIVER in animals due to viral infection.Hepatitis, Autoimmune: A chronic self-perpetuating hepatocellular INFLAMMATION of unknown cause, usually with HYPERGAMMAGLOBULINEMIA and serum AUTOANTIBODIES.Hepatitis A Virus, Human: A strain of HEPATITIS A VIRUS which causes hepatitis in humans. The virus replicates in hepatocytes and is presumed to reach the intestine via the bile duct. Transmission occurs by the fecal-oral route.Hepatitis Viruses: Any of the viruses that cause inflammation of the liver. They include both DNA and RNA viruses as well viruses from humans and animals.Hepatitis Delta Virus: A defective virus, containing particles of RNA nucleoprotein in virion-like form, present in patients with acute hepatitis B and chronic hepatitis. It requires the presence of a hepadnavirus for full replication. This is the lone species in the genus Deltavirus.Hepatitis D: INFLAMMATION of the LIVER in humans caused by HEPATITIS DELTA VIRUS, a defective RNA virus that can only infect HEPATITIS B patients. For its viral coating, hepatitis delta virus requires the HEPATITIS B SURFACE ANTIGENS produced by these patients. Hepatitis D can occur either concomitantly with (coinfection) or subsequent to (superinfection) hepatitis B infection. Similar to hepatitis B, it is primarily transmitted by parenteral exposure, such as transfusion of contaminated blood or blood products, but can also be transmitted via sexual or intimate personal contact.Hepatitis, Animal: INFLAMMATION of the LIVER in non-human animals.Viral Hepatitis Vaccines: Any vaccine raised against any virus or viral derivative that causes hepatitis.Antiviral Agents: 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.Murine hepatitis virus: A species of the CORONAVIRUS genus causing hepatitis in mice. Four strains have been identified as MHV 1, MHV 2, MHV 3, and MHV 4 (also known as MHV-JHM, which is neurotropic and causes disseminated encephalomyelitis with demyelination as well as focal liver necrosis).Hepatitis C Antigens: Antigens of the virions of HEPACIVIRUS, their surface, core, or other associated antigens.Hepatovirus: A genus of PICORNAVIRIDAE causing infectious hepatitis naturally in humans and experimentally in other primates. It is transmitted through fecal contamination of food or water. HEPATITIS A VIRUS is the type species.RNA, Viral: Ribonucleic acid that makes up the genetic material of viruses.Liver Cirrhosis: Liver disease in which the normal microcirculation, the gross vascular anatomy, and the hepatic architecture have been variably destroyed and altered with fibrous septa surrounding regenerated or regenerating parenchymal nodules.Interferon-alpha: One of the type I interferons produced by peripheral blood leukocytes or lymphoblastoid cells. In addition to antiviral activity, it activates NATURAL KILLER CELLS and B-LYMPHOCYTES, and down-regulates VASCULAR ENDOTHELIAL GROWTH FACTOR expression through PI-3 KINASE and MAPK KINASES signaling pathways.Hepatitis A Antigens: Antigens produced by various strains of HEPATITIS A VIRUS such as the human hepatitis A virus (HEPATITIS A VIRUS, HUMAN).Hepatitis delta Antigens: Antigens produced by various strains of HEPATITIS D VIRUS.Hepatitis Antigens: Antigens from any of the hepatitis viruses including surface, core, and other associated antigens.Hepatitis, Alcoholic: INFLAMMATION of the LIVER due to ALCOHOL ABUSE. It is characterized by NECROSIS of HEPATOCYTES, infiltration by NEUTROPHILS, and deposit of MALLORY BODIES. Depending on its severity, the inflammatory lesion may be reversible or progress to LIVER CIRRHOSIS.Ribavirin: A nucleoside antimetabolite antiviral agent that blocks nucleic acid synthesis and is used against both RNA and DNA viruses.Hepatitis B Virus, Duck: A DNA virus that closely resembles human hepatitis B virus. It has been recovered from naturally infected ducks.Alanine Transaminase: An enzyme that catalyzes the conversion of L-alanine and 2-oxoglutarate to pyruvate and L-glutamate. (From Enzyme Nomenclature, 1992) EC 2.6.1.2.DNA, Viral: Deoxyribonucleic acid that makes up the genetic material of viruses.Viral Nonstructural Proteins: Proteins encoded by a VIRAL GENOME that are produced in the organisms they infect, but not packaged into the VIRUS PARTICLES. Some of these proteins may play roles within the infected cell during VIRUS REPLICATION or act in regulation of virus replication or VIRUS ASSEMBLY.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Carcinoma, Hepatocellular: A primary malignant neoplasm of epithelial liver cells. It ranges from a well-differentiated tumor with EPITHELIAL CELLS indistinguishable from normal HEPATOCYTES to a poorly differentiated neoplasm. The cells may be uniform or markedly pleomorphic, or form GIANT CELLS. Several classification schemes have been suggested.Hepatitis B Virus, Woodchuck: An ORTHOHEPADNAVIRUS causing chronic liver disease and hepatocellular carcinoma in woodchucks. It closely resembles the human hepatitis B virus.Liver Neoplasms: Tumors or cancer of the LIVER.Lamivudine: 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.Virus Replication: 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.Polyethylene Glycols: Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.Viral Core Proteins: Proteins found mainly in icosahedral DNA and RNA viruses. They consist of proteins directly associated with the nucleic acid inside the NUCLEOCAPSID.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Hepatitis D, Chronic: INFLAMMATION of the LIVER in humans caused by HEPATITIS DELTA VIRUS in conjunction with HEPATITIS B VIRUS and lasting six months or more.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.Marmota: A genus of Sciuridae consisting of 14 species. They are shortlegged, burrowing rodents which hibernate in winter.Seroepidemiologic Studies: EPIDEMIOLOGIC STUDIES based on the detection through serological testing of characteristic change in the serum level of specific ANTIBODIES. Latent subclinical infections and carrier states can thus be detected in addition to clinically overt cases.Liver Transplantation: The transference of a part of or an entire liver from one human or animal to another.Viral Load: 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.Carrier State: The condition of harboring an infective organism without manifesting symptoms of infection. The organism must be readily transmissible to another susceptible host.Genome, Viral: The complete genetic complement contained in a DNA or RNA molecule in a virus.Hepatocytes: The main structural component of the LIVER. They are specialized EPITHELIAL CELLS that are organized into interconnected plates called lobules.Flaviviridae: A family of RNA viruses, many of which cause disease in humans and domestic animals. There are three genera FLAVIVIRUS; PESTIVIRUS; and HEPACIVIRUS, as well as several unassigned species.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Blood DonorsLiver Function Tests: Blood tests that are used to evaluate how well a patient's liver is working and also to help diagnose liver conditions.Liver Diseases: Pathological processes of the LIVER.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Pan troglodytes: The common chimpanzee, a species of the genus Pan, family HOMINIDAE. It lives in Africa, primarily in the tropical rainforests. There are a number of recognized subspecies.Acute Disease: Disease having a short and relatively severe course.Drug Therapy, Combination: Therapy with two or more separate preparations given for a combined effect.Jaundice: A clinical manifestation of HYPERBILIRUBINEMIA, characterized by the yellowish staining of the SKIN; MUCOUS MEMBRANE; and SCLERA. Clinical jaundice usually is a sign of LIVER dysfunction.Substance Abuse, Intravenous: Abuse, overuse, or misuse of a substance by its injection into a vein.Aspartate Aminotransferases: Enzymes of the transferase class that catalyze the conversion of L-aspartate and 2-ketoglutarate to oxaloacetate and L-glutamate. EC 2.6.1.1.Drug-Induced Liver Injury: A spectrum of clinical liver diseases ranging from mild biochemical abnormalities to ACUTE LIVER FAILURE, caused by drugs, drug metabolites, and chemicals from the environment.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.Replicon: Any DNA sequence capable of independent replication or a molecule that possesses a REPLICATION ORIGIN and which is therefore potentially capable of being replicated in a suitable cell. (Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)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.DucksInterferons: Proteins secreted by vertebrate cells in response to a wide variety of inducers. They confer resistance against many different viruses, inhibit proliferation of normal and malignant cells, impede multiplication of intracellular parasites, enhance macrophage and granulocyte phagocytosis, augment natural killer cell activity, and show several other immunomodulatory functions.Cryoglobulinemia: A condition characterized by the presence of abnormal quantities of CRYOGLOBULINS in the blood. Upon cold exposure, these abnormal proteins precipitate into the microvasculature leading to restricted blood flow in the exposed areas.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Chronic Disease: Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care. (Dictionary of Health Services Management, 2d ed)Organophosphonates: 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.Cell Line: Established cell cultures that have the potential to propagate indefinitely.HIV Infections: Includes the spectrum of human immunodeficiency virus infections that range from asymptomatic seropositivity, thru AIDS-related complex (ARC), to acquired immunodeficiency syndrome (AIDS).Liver Failure: Severe inability of the LIVER to perform its normal metabolic functions, as evidenced by severe JAUNDICE and abnormal serum levels of AMMONIA; BILIRUBIN; ALKALINE PHOSPHATASE; ASPARTATE AMINOTRANSFERASE; LACTATE DEHYDROGENASES; and albumin/globulin ratio. (Blakiston's Gould Medical Dictionary, 4th ed)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.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Drug Resistance, Viral: The ability of viruses to resist or to become tolerant to chemotherapeutic agents or antiviral agents. This resistance is acquired through gene mutation.Biopsy: Removal and pathologic examination of specimens in the form of small pieces of tissue from the living body.Coinfection: Simultaneous infection of a host organism by two or more pathogens. In virology, coinfection commonly refers to simultaneous infection of a single cell by two or more different viruses.Antigens, CD81: Tetraspanin proteins that are involved in a variety of cellular functions including BASEMENT MEMBRANE assembly, and in the formation of a molecular complexes on the surface of LYMPHOCYTES.Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.Vaccination: Administration of vaccines to stimulate the host's immune response. This includes any preparation intended for active immunological prophylaxis.Hepadnaviridae: A family of hepatotropic DNA viruses which contains double-stranded DNA genomes and causes hepatitis in humans and animals. There are two genera: AVIHEPADNAVIRUS and ORTHOHEPADNAVIRUS. Hepadnaviruses include HEPATITIS B VIRUS, duck hepatitis B virus (HEPATITIS B VIRUS, DUCK), heron hepatitis B virus, ground squirrel hepatitis virus, and woodchuck hepatitis B virus (HEPATITIS B VIRUS, WOODCHUCK).Viremia: The presence of viruses in the blood.Blood Transfusion: The introduction of whole blood or blood component directly into the blood stream. (Dorland, 27th ed)Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Hepatitis Virus, Duck: Unassigned species, in the family PICORNAVIRIDAE, causing high mortality in ducklings 3 days to 3 weeks old.Egypt: A country in northern Africa, bordering the Mediterranean Sea, between Libya and the Gaza Strip, and the Red Sea north of Sudan, and includes the Asian Sinai Peninsula Its capital is Cairo.Adenine: A purine base and a fundamental unit of ADENINE NUCLEOTIDES.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Recurrence: The return of a sign, symptom, or disease after a remission.Hepadnaviridae Infections: Virus diseases caused by the HEPADNAVIRIDAE.Time Factors: Elements of limited time intervals, contributing to particular results or situations.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.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.Tattooing: The indelible marking of TISSUES, primarily SKIN, by pricking it with NEEDLES to imbed various COLORING AGENTS. Tattooing of the CORNEA is done to colorize LEUKOMA spots.Viral Proteins: Proteins found in any species of virus.Liver Failure, Acute: A form of rapid-onset LIVER FAILURE, also known as fulminant hepatic failure, caused by severe liver injury or massive loss of HEPATOCYTES. It is characterized by sudden development of liver dysfunction and JAUNDICE. Acute liver failure may progress to exhibit cerebral dysfunction even HEPATIC COMA depending on the etiology that includes hepatic ISCHEMIA, drug toxicity, malignant infiltration, and viral hepatitis such as post-transfusion HEPATITIS B and HEPATITIS C.Gene Expression Regulation, Viral: Any of the processes by which cytoplasmic factors influence the differential control of gene action in viruses.China: A country spanning from central Asia to the Pacific Ocean.Hepatitis, Infectious Canine: A contagious disease caused by canine adenovirus (ADENOVIRUSES, CANINE) infecting the LIVER, the EYE, the KIDNEY, and other organs in dogs, other canids, and bears. Symptoms include FEVER; EDEMA; VOMITING; and DIARRHEA.Pregnancy Complications, Infectious: The co-occurrence of pregnancy and an INFECTION. The infection may precede or follow FERTILIZATION.Serologic Tests: Diagnostic procedures involving immunoglobulin reactions.Reverse Transcriptase Inhibitors: Inhibitors of reverse transcriptase (RNA-DIRECTED DNA POLYMERASE), an enzyme that synthesizes DNA on an RNA template.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Virion: 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.Antigens, Viral: Substances elaborated by viruses that have antigenic activity.GB virus C: A species of virus (unassigned to a genus) in the family FLAVIVIRIDAE. It is genetically heterogeneous, of human origin, and transmitted by blood or blood products. Despite its alternate name (Hepatitis G virus), its pathogenicity remains controversial.5' Untranslated Regions: The sequence at the 5' end of the messenger RNA that does not code for product. This sequence contains the ribosome binding site and other transcription and translation regulating sequences.Flaviviridae Infections: Infections with viruses of the family FLAVIVIRIDAE.Genes, Viral: The functional hereditary units of VIRUSES.Infectious Disease Transmission, Vertical: 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.Immunoglobulin M: A class of immunoglobulin bearing mu chains (IMMUNOGLOBULIN MU-CHAINS). IgM can fix COMPLEMENT. The name comes from its high molecular weight and originally being called a macroglobulin.Bilirubin: A bile pigment that is a degradation product of HEME.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Transaminases: A subclass of enzymes of the transferase class that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally a 2-keto acid). Most of these enzymes are pyridoxyl phosphate proteins. (Dorland, 28th ed) EC 2.6.1.Blood-Borne Pathogens: Infectious organisms in the BLOOD, of which the predominant medical interest is their contamination of blood-soiled linens, towels, gowns, BANDAGES, other items from individuals in risk categories, NEEDLES and other sharp objects, MEDICAL WASTE and DENTAL WASTE, all of which health workers are exposed to. This concept is differentiated from the clinical conditions of BACTEREMIA; VIREMIA; and FUNGEMIA where the organism is present in the blood of a patient as the result of a natural infectious process.Saguinus: A genus in the subfamily CALLITRICHINAE consisting of 12 species and found in Panama as well as South America. Species seen most frequently in the literature are S. oedipus (cotton-top marmoset), S. nigricollis, and S. fusicollis.Biological Markers: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.Disease Progression: The worsening of a disease over time. This concept is most often used for chronic and incurable diseases where the stage of the disease is an important determinant of therapy and prognosis.Immunization Schedule: Schedule giving optimum times usually for primary and/or secondary immunization.Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Coronavirus Infections: Virus diseases caused by the CORONAVIRUS genus. Some specifics include transmissible enteritis of turkeys (ENTERITIS, TRANSMISSIBLE, OF TURKEYS); FELINE INFECTIOUS PERITONITIS; and transmissible gastroenteritis of swine (GASTROENTERITIS, TRANSMISSIBLE, OF SWINE).Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.BrazilCase-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Epitopes: Sites on an antigen that interact with specific antibodies.Immunoglobulin G: The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.Disease Outbreaks: Sudden increase in the incidence of a disease. The concept includes EPIDEMICS and PANDEMICS.Sciuridae: A family of the order Rodentia which contains 49 genera. Some of the more common genera are MARMOTA, which includes the marmot and woodchuck; Sciurus, the gray squirrel, S. carolinensis, and the fox squirrel, S. niger; Tamias, the eastern and western chipmunk; and Tamiasciurus, the red squirrel. The flying squirrels, except the scaly-tailed Anomaluridae, also belong to this family.Transfection: 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.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.DNA Primers: 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.RNA Replicase: An enzyme that catalyses RNA-template-directed extension of the 3'- end of an RNA strand by one nucleotide at a time, and can initiate a chain de novo. (Enzyme Nomenclature, 1992, p293)Immunization Programs: Organized services to administer immunization procedures in the prevention of various diseases. The programs are made available over a wide range of sites: schools, hospitals, public health agencies, voluntary health agencies, etc. They are administered to an equally wide range of population groups or on various administrative levels: community, municipal, state, national, international.Reverse Transcriptase Polymerase Chain Reaction: A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.Hepatic Encephalopathy: A syndrome characterized by central nervous system dysfunction in association with LIVER FAILURE, including portal-systemic shunts. Clinical features include lethargy and CONFUSION (frequently progressing to COMA); ASTERIXIS; NYSTAGMUS, PATHOLOGIC; brisk oculovestibular reflexes; decorticate and decerebrate posturing; MUSCLE SPASTICITY; and bilateral extensor plantar reflexes (see REFLEX, BABINSKI). ELECTROENCEPHALOGRAPHY may demonstrate triphasic waves. (From Adams et al., Principles of Neurology, 6th ed, pp1117-20; Plum & Posner, Diagnosis of Stupor and Coma, 3rd ed, p222-5)Genetic Variation: Genotypic differences observed among individuals in a population.Sexually Transmitted Diseases, Viral: Viral diseases which are transmitted or propagated by sexual conduct.Virus Internalization: The entering of cells by viruses following VIRUS ATTACHMENT. This is achieved by ENDOCYTOSIS, by direct MEMBRANE FUSION of the viral membrane with the CELL MEMBRANE, or by translocation of the whole virus across the cell membrane.Gene Products, pol: 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.Orthohepadnavirus: A genus of HEPADNAVIRIDAE causing hepatitis in humans, woodchucks (HEPATITIS B VIRUS, WOODCHUCK) and ground squirrels. hepatitis b virus is the type species.DNA Virus InfectionsPakistanLiver Cirrhosis, Biliary: FIBROSIS of the hepatic parenchyma due to obstruction of BILE flow (CHOLESTASIS) in the intrahepatic or extrahepatic bile ducts (BILE DUCTS, INTRAHEPATIC; BILE DUCTS, EXTRAHEPATIC). Primary biliary cirrhosis involves the destruction of small intra-hepatic bile ducts and bile secretion. Secondary biliary cirrhosis is produced by prolonged obstruction of large intrahepatic or extrahepatic bile ducts from a variety of causes.Trans-Activators: Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins.Liver Cirrhosis, Alcoholic: FIBROSIS of the hepatic parenchyma due to chronic excess ALCOHOL DRINKING.Protein PrecursorsHemophilia A: The classic hemophilia resulting from a deficiency of factor VIII. It is an inherited disorder of blood coagulation characterized by a permanent tendency to hemorrhage.Prisons: Penal institutions, or places of confinement for war prisoners.Immunoenzyme Techniques: Immunologic techniques based on the use of: (1) enzyme-antibody conjugates; (2) enzyme-antigen conjugates; (3) antienzyme antibody followed by its homologous enzyme; or (4) enzyme-antienzyme complexes. These are used histologically for visualizing or labeling tissue specimens.Virus Activation: 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.Virus Assembly: The assembly of VIRAL STRUCTURAL PROTEINS and nucleic acid (VIRAL DNA or VIRAL RNA) to form a VIRUS PARTICLE.Virology: The study of the structure, growth, function, genetics, and reproduction of viruses, and VIRUS DISEASES.Immunoglobulins: Multi-subunit proteins which function in IMMUNITY. They are produced by B LYMPHOCYTES from the IMMUNOGLOBULIN GENES. They are comprised of two heavy (IMMUNOGLOBULIN HEAVY CHAINS) and two light chains (IMMUNOGLOBULIN LIGHT CHAINS) with additional ancillary polypeptide chains depending on their isoforms. The variety of isoforms include monomeric or polymeric forms, and transmembrane forms (B-CELL ANTIGEN RECEPTORS) or secreted forms (ANTIBODIES). They are divided by the amino acid sequence of their heavy chains into five classes (IMMUNOGLOBULIN A; IMMUNOGLOBULIN D; IMMUNOGLOBULIN E; IMMUNOGLOBULIN G; IMMUNOGLOBULIN M) and various subclasses.Cross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.PrisonersRadioimmunoassay: Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.Fatty Liver: Lipid infiltration of the hepatic parenchymal cells resulting in a yellow-colored liver. The abnormal lipid accumulation is usually in the form of TRIGLYCERIDES, either as a single large droplet or multiple small droplets. Fatty liver is caused by an imbalance in the metabolism of FATTY ACIDS.Tupaia: A genus of tree shrews of the family TUPAIIDAE which consists of about 12 species. One of the most frequently encountered species is T. glis. Members of this genus inhabit rain forests and secondary growth areas in southeast Asia.Nucleosides: Purine or pyrimidine bases attached to a ribose or deoxyribose. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Vaccines, Synthetic: 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.TaiwanInfant, Newborn: An infant during the first month after birth.Nucleocapsid: A protein-nucleic acid complex which forms part or all of a virion. It consists of a CAPSID plus enclosed nucleic acid. Depending on the virus, the nucleocapsid may correspond to a naked core or be surrounded by a membranous envelope.Cell Line, Tumor: A cell line derived from cultured tumor cells.GuanineTorque teno virus: A species of non-enveloped DNA virus in the genus ANELLOVIRUS, associated with BLOOD TRANSFUSIONS; and HEPATITIS. However, no etiological role has been found for TTV in hepatitis.Renal Dialysis: Therapy for the insufficient cleansing of the BLOOD by the kidneys based on dialysis and including hemodialysis, PERITONEAL DIALYSIS, and HEMODIAFILTRATION.Plasmids: 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.Viral Structural Proteins: Viral proteins that are components of the mature assembled VIRUS PARTICLES. They may include nucleocapsid core proteins (gag proteins), enzymes packaged within the virus particle (pol proteins), and membrane components (env proteins). These do not include the proteins encoded in the VIRAL GENOME that are produced in infected cells but which are not packaged in the mature virus particle,i.e. the so called non-structural proteins (VIRAL NONSTRUCTURAL PROTEINS).Disease Transmission, Infectious: The transmission of infectious disease or pathogens. When transmission is within the same species, the mode can be horizontal or vertical (INFECTIOUS DISEASE TRANSMISSION, VERTICAL).Hemodialysis Units, Hospital: Hospital units in which care is provided the hemodialysis patient. This includes hemodialysis centers in hospitals.United StatesHep G2 Cells: A human liver tumor cell line used to study a variety of liver-specific metabolic functions.Infectious Disease Transmission, Professional-to-Patient: The transmission of infectious disease or pathogens from health professional or health care worker to patients. It includes transmission via direct or indirect exposure to bacterial, fungal, parasitic, or viral agents.Interleukins: Soluble factors which stimulate growth-related activities of leukocytes as well as other cell types. They enhance cell proliferation and differentiation, DNA synthesis, secretion of other biologically active molecules and responses to immune and inflammatory stimuli.Reagent Kits, Diagnostic: Commercially prepared reagent sets, with accessory devices, containing all of the major components and literature necessary to perform one or more designated diagnostic tests or procedures. They may be for laboratory or personal use.alpha-Fetoproteins: The first alpha-globulins to appear in mammalian sera during FETAL DEVELOPMENT and the dominant serum proteins in early embryonic life.Polyproteins: Proteins which are synthesized as a single polymer and then cleaved into several distinct proteins.Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.