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Avihepadnavirus
''Avihepadnavirus'' is a genus of viruses, in the family ''Hepadnaviridae''. Birds serve as natural hosts. There are three species in this genus. Diseases associated with this genus include: hepatitis, hepatocellular carcinomas (chronic infections), and cirrhosis. Taxonomy The genus contains the following species: * ''Duck hepatitis B virus'' * '' Heron hepatitis B virus'' * ''Parrot hepatitis B virus'' Structure Viruses in the genus ''Avihepadnavirus'' are enveloped, with spherical geometries, and T=4 symmetry. The diameter is around 42 nm. Genomes are circular, around 3.2kb in length. The genome codes for 7 proteins. Life cycle Viral replication is nucleo-cytoplasmic. Replication follows the dsDNA(RT) replication model. DNA-templated transcription, specifically dsDNA-RT transcription, with some alternative splicing mechanism is the method of transcription. Translation takes place by ribosomal shunting Ribosome shunting is a mechanism of translation initiation in which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepadnaviridae
''Hepadnaviridae'' is a family of viruses. Humans, apes, and birds serve as natural hosts. There are currently 18 species in this family, divided among 5 genera. Its best-known member is hepatitis B virus. Diseases associated with this family include: liver infections, such as hepatitis, hepatocellular carcinomas (chronic infections), and cirrhosis. It is the sole accepted family in the order ''Blubervirales''. Taxonomy The following genera are recognized: * '' Avihepadnavirus'' * '' Orthohepadnavirus'' * '' Herpetohepadnavirus'' * '' Metahepadnavirus'' * '' Parahepadnavirus'' History and discovery Although liver diseases transmissible among human populations were identified early in the history of medicine, the first known hepatitis with a viral etiological agent was Hepatitis A, in the picornaviridae family. Hepatitis B Virus (HBV) was identified as an infection distinct from Hepatitis A through its contamination of measles, mumps, and yellow fever vaccines in the 1930s and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duck Hepatitis B Virus
''Duck hepatitis B virus'', abbreviated DHBV, is part of the genus '' Avihepadnavirus'' of the '' Hepadnaviridae'', and is the causal agent of duck hepatitis B. DHBV is a small DNA virus with a diameter of 40–45 nm. The viral envelope is made up from host cell lipid, with viral surface antigens (DHBsAg). The icosahedral nucleocapsid within, is composed of the virus core antigen (DHBcAg) and surrounds the DNA genome and viral polymerase. The viral genome is a circular double stranded DNA molecule about 3000 base pairs long. The genome has three overlapping open reading frames or ORFs: * C-ORF – encoding the core antigen and pre-core protein which are processed and secreted as DHBcAg * S-ORF – codes for the surface antigen DHBsAg * P-ORF – encoding the viral polymerase. On binding and entry of the virus to the host cell, the genome is transported to the nucleus to be transcribed. Novel viral RNA is then transferred to the cytoplasm for translation and sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parrot Hepatitis B Virus
Parrots, also known as psittacines (), are birds of the roughly 398 species in 92 genus (biology), genera comprising the order (biology), order Psittaciformes (), found mostly in tropics, tropical and subtropics, subtropical regions. The order is subdivided into three superfamilies: the true parrot, Psittacoidea ("true" parrots), the Cockatoo, Cacatuoidea (cockatoos), and the New Zealand parrot, Strigopoidea (New Zealand parrots). One-third of all parrot species are threatened by extinction, with higher aggregate extinction risk (Red List Index, IUCN Red List Index) than any other comparable bird group. Parrots have a generally pantropical distribution with several species inhabiting temperateness, temperate regions in the Southern Hemisphere, as well. The greatest biodiversity, diversity of parrots is in South America and Australasia. Characteristic features of parrots include a strong, curved beak, bill, an upright stance, strong legs, and clawed Dactyly#In birds, zygodactyl f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
A virus is a wikt:submicroscopic, submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898,Dimmock p. 4 more than 9,000 virus species have been described in detail of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles, or ''virions'', consisti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepatitis
Hepatitis is inflammation of the liver parenchyma, liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes (jaundice), Anorexia (symptom), poor appetite, vomiting, fatigue (medicine), tiredness, abdominal pain, and diarrhea. Hepatitis is ''acute (medicine), acute'' if it resolves within six months, and ''chronic condition, chronic'' if it lasts longer than six months. Acute hepatitis can self-limiting (biology), resolve on its own, progress to chronic hepatitis, or (rarely) result in acute liver failure. Chronic hepatitis may progress to scarring of the liver (cirrhosis), liver failure, and liver cancer. Hepatitis is most commonly caused by the virus ''hepatovirus A'', ''hepatitis B virus, B'', ''hepatitis C virus, C'', ''hepatitis D virus, D'', and ''hepatitis E virus, E''. Other Viral hepatitis, viruses can also cause liver inflammation, including cytomegalovirus, Epstein–Barr virus, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepatocellular Carcinoma
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide. It occurs in the setting of chronic liver inflammation, and is most closely linked to chronic viral hepatitis infection (hepatitis B or C) or exposure to toxins such as alcohol, aflatoxin, or pyrrolizidine alkaloids. Certain diseases, such as hemochromatosis and alpha 1-antitrypsin deficiency, markedly increase the risk of developing HCC. Metabolic syndrome and NASH are also increasingly recognized as risk factors for HCC. As with any cancer, the treatment and prognosis of HCC vary depending on the specifics of tumor histology, size, how far the cancer has spread, and overall health. The vast majority of HCC cases and the lowest survival rates after treatment occur in Asia and sub-Saharan Africa, in countries where hepatitis B infection is ende ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cirrhosis
Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue repair and subsequent formation of scar tissue, which over time can replace normal parenchyma, functioning tissue, leading to the impaired liver function of cirrhosis. The disease typically develops slowly over months or years. Early symptoms may include Fatigue (medicine), tiredness, Asthenia, weakness, Anorexia (symptom), loss of appetite, weight loss, unexplained weight loss, nausea and vomiting, and discomfort in the right upper quadrant of the abdomen. As the disease worsens, symptoms may include Pruritus, itchiness, peripheral edema, swelling in the lower legs, ascites, fluid build-up in the abdomen, jaundice, coagulopathy, bruising easily, and the development of spider angioma, spider-like blood vessels in the skin. The fluid build-up in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomal Shunting
Ribosome shunting is a mechanism of translation initiation in which ribosomes bypass, or "shunt over", parts of the 5' untranslated region to reach the start codon. However, a benefit of ribosomal shunting is that it can translate backwards allowing more information to be stored than usual in an mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of synthesizing a protein. mRNA is created during the ... molecule. Some viral RNAs have been shown to use ribosome shunting as a more efficient form of translation during certain stages of viral life cycle or when translation initiation factors are scarce (e.g. cleavage by viral proteases). Some viruses known to use this mechanism include adenovirus, Sendai virus, human papillomavirus, duck hepatitis B pararetrovirus, rice tungro bacilliform viruses, and cauliflower mosaic virus. In these viru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
