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 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 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 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 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: INFLAMMATION of the LIVER.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.Immunoelectrophoresis: A technique that combines protein electrophoresis and double immunodiffusion. In this procedure proteins are first separated by gel electrophoresis (usually agarose), then made visible by immunodiffusion of specific antibodies. A distinct elliptical precipitin arc results for each protein detectable by the antisera.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.Counterimmunoelectrophoresis: Immunoelectrophoresis in which immunoprecipitation occurs when antigen at the cathode is caused to migrate in an electric field through a suitable medium of diffusion against a stream of antibody migrating from the anode as a result of endosmotic flow.Hepatitis B Core Antigens: The hepatitis B antigen within the core of the Dane particle, the infectious hepatitis virion.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 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.Blood DonorsCarrier State: The condition of harboring an infective organism without manifesting symptoms of infection. The organism must be readily transmissible to another susceptible host.Hemagglutination Tests: Sensitive tests to measure certain antigens, antibodies, or viruses, using their ability to agglutinate certain erythrocytes. (From Stedman, 26th ed)Radioimmunoassay: 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.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.Antigens: Substances that are recognized by the immune system and induce an immune reaction.Immunodiffusion: Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction.Complement Fixation Tests: Serologic tests based on inactivation of complement by the antigen-antibody complex (stage 1). Binding of free complement can be visualized by addition of a second antigen-antibody system such as red cells and appropriate red cell antibody (hemolysin) requiring complement for its completion (stage 2). Failure of the red cells to lyse indicates that a specific antigen-antibody reaction has taken place in stage 1. If red cells lyse, free complement is present indicating no antigen-antibody reaction occurred in stage 1.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 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.Blood Transfusion: The introduction of whole blood or blood component directly into the blood stream. (Dorland, 27th ed)Liver Diseases: Pathological processes of the LIVER.Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.ABO Blood-Group System: The major human blood type system which depends on the presence or absence of two antigens A and B. Type O occurs when neither A nor B is present and AB when both are present. A and B are genetic factors that determine the presence of enzymes for the synthesis of certain glycoproteins mainly in the red cell membrane.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 Virus, Duck: A DNA virus that closely resembles human hepatitis B virus. It has been recovered from naturally infected ducks.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 Antibodies: Immunoglobulins raised by any form of viral hepatitis; some of these antibodies are used to diagnose the specific kind of hepatitis.Antigens, Viral: Substances elaborated by viruses that have antigenic activity.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.Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.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 A Vaccines: Vaccines or candidate vaccines used to prevent infection with hepatitis A virus (HEPATOVIRUS).DNA, Viral: Deoxyribonucleic acid that makes up the genetic material of viruses.Hepatitis C Antibodies: Antibodies to the HEPATITIS C ANTIGENS including antibodies to envelope, core, and non-structural proteins.Iodine Radioisotopes: Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.Antigens, Neoplasm: Proteins, glycoprotein, or lipoprotein moieties on surfaces of tumor cells that are usually identified by monoclonal antibodies. Many of these are of either embryonic or viral origin.Hepatitis, Viral, Animal: INFLAMMATION of the LIVER in animals due to viral infection.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.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.Blood Group Antigens: Sets of cell surface antigens located on BLOOD CELLS. They are usually membrane GLYCOPROTEINS or GLYCOLIPIDS that are antigenically distinguished by their carbohydrate moieties.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.Viral Hepatitis Vaccines: Any vaccine raised against any virus or viral derivative that causes hepatitis.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.HLA Antigens: Antigens determined by leukocyte loci found on chromosome 6, the major histocompatibility loci in humans. They are polypeptides or glycoproteins found on most nucleated cells and platelets, determine tissue types for transplantation, and are associated with certain diseases.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.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.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 A Antibodies: Antibodies to the HEPATITIS A 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, Autoimmune: A chronic self-perpetuating hepatocellular INFLAMMATION of unknown cause, usually with HYPERGAMMAGLOBULINEMIA and serum AUTOANTIBODIES.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 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.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.Liver Neoplasms: Tumors or cancer of the LIVER.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.Hepatitis, Animal: INFLAMMATION of the LIVER in non-human animals.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.Epitopes: Sites on an antigen that interact with specific antibodies.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.RNA, Viral: Ribonucleic acid that makes up the genetic material of viruses.HLA-B Antigens: Class I human histocompatibility (HLA) surface antigens encoded by more than 30 detectable alleles on locus B of the HLA complex, the most polymorphic of all the HLA specificities. Several of these antigens (e.g., HLA-B27, -B7, -B8) are strongly associated with predisposition to rheumatoid and other autoimmune disorders. Like other class I HLA determinants, they are involved in the cellular immune reactivity of cytolytic T lymphocytes.Hepatitis B Virus, Woodchuck: An ORTHOHEPADNAVIRUS causing chronic liver disease and hepatocellular carcinoma in woodchucks. It closely resembles the human hepatitis B virus.Hepatitis delta Antigens: Antigens produced by various strains of HEPATITIS D VIRUS.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 C Antigens: Antigens of the virions of HEPACIVIRUS, their surface, core, or other associated antigens.Hepatitis Antigens: Antigens from any of the hepatitis viruses including surface, core, and other associated antigens.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.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.HLA-A Antigens: Polymorphic class I human histocompatibility (HLA) surface antigens present on almost all nucleated cells. At least 20 antigens have been identified which are encoded by the A locus of multiple alleles on chromosome 6. They serve as targets for T-cell cytolytic responses and are involved with acceptance or rejection of tissue/organ grafts.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.Immunoglobulin G: The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.Antigens, Protozoan: Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.DucksAntibodies, Monoclonal: Antibodies produced by a single clone of cells.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).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.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.Hepatitis A Antigens: Antigens produced by various strains of HEPATITIS A VIRUS such as the human hepatitis A virus (HEPATITIS A VIRUS, HUMAN).Cell Line: Established cell cultures that have the potential to propagate indefinitely.Antigens, Polyomavirus Transforming: Polyomavirus antigens which cause infection and cellular transformation. The large T antigen is necessary for the initiation of viral DNA synthesis, repression of transcription of the early region and is responsible in conjunction with the middle T antigen for the transformation of primary cells. Small T antigen is necessary for the completion of the productive infection cycle.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Antigens, CD: Differentiation antigens residing on mammalian leukocytes. CD stands for cluster of differentiation, which refers to groups of monoclonal antibodies that show similar reactivity with certain subpopulations of antigens of a particular lineage or differentiation stage. The subpopulations of antigens are also known by the same CD designation.Herpesvirus 2, Gallid: The type species of the genus MARDIVIRUS in the family HERPESVIRIDAE. It is the etiologic agent of MAREK DISEASE, infecting domestic fowl and wild birds.Vaccination: Administration of vaccines to stimulate the host's immune response. This includes any preparation intended for active immunological prophylaxis.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.Antigen-Antibody Reactions: The processes triggered by interactions of ANTIBODIES with their ANTIGENS.Marmota: A genus of Sciuridae consisting of 14 species. They are shortlegged, burrowing rodents which hibernate in winter.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.Cross Reactions: Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.Antigens, Fungal: Substances of fungal origin 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.H-2 Antigens: The major group of transplantation antigens in the mouse.Hepadnaviridae Infections: Virus diseases caused by the HEPADNAVIRIDAE.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.Antigens, Helminth: Any part or derivative of a helminth that elicits an immune reaction. The most commonly seen helminth antigens are those of the schistosomes.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.Adenine: A purine base and a fundamental unit of ADENINE NUCLEOTIDES.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.Liver Transplantation: The transference of a part of or an entire liver from one human or animal to another.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.Ribavirin: A nucleoside antimetabolite antiviral agent that blocks nucleic acid synthesis and is used against both RNA and DNA viruses.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.Genome, Viral: The complete genetic complement contained in a DNA or RNA molecule in a virus.Recombinant Proteins: Proteins prepared by recombinant DNA technology.