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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 subsequent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avihepadnavirus
''Avihepadnavirus'' is a genus of viruses, in the family ''Hepadnaviridae''. Birds serve as natural hosts. There are five species in this genus. Diseases associated with this genus include: hepatitis, hepatocellular carcinomas (chronic infections), and cirrhosis. Taxonomy The genus contains the following species, listed by scientific name and followed by the exemplar virus of the species: * ''Avihepadnavirus anatigruidae'', 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 ma ... * ''Avihepadnavirus ciconiardeae'', Heron hepatitis B virus * ''Avihepadnavirus psittaunius'', Parrot hepatitis B virus 1 * ''Avihepadnavirus psittaduorum'', Parrot hepatitis B virus 2 * ''Avihepadnavirus bonicursoris'', Elegant-crested tinamou hepatitis B virus Structure Viruses in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viral Entry
Viral entry is the earliest stage of infection in the viral life cycle, as the virus comes into contact with the host cell (biology), cell and introduces viral material into the cell. The major steps involved in viral entry are shown below. Despite the variation among viruses, there are several shared generalities concerning viral entry. Reducing cellular proximity How a virus enters a cell is different depending on the type of virus it is. A virus with a Viral envelope, nonenveloped capsid enters the cell by attaching to the attachment factor located on a host cell. It then enters the cell by endocytosis or by making a hole in the membrane of the host cell and inserting its viral genome. Cell entry by enveloped viruses is more complicated. Enveloped viruses enter the cell by attaching to an attachment factor located on the surface of the host cell. They then enter by endocytosis or a direct membrane fusion event. The fusion event is when the virus membrane and the host cell m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Model
An animal model (short for animal disease model) is a living, non-human, often genetic-engineered animal used during the research and investigation of human disease, for the purpose of better understanding the disease process without the risk of harming a human. Although biological activity in an animal model does not ensure an effect in humans, many drugs, treatments and cures for human diseases are developed in part with the guidance of animal models. Animal models representing specific taxonomic groups in the research and study of developmental processes are also referred to as model organisms. There are three main types of animal models: Homologous, Isomorphic and Predictive. Homologous animals have the same causes, symptoms and treatment options as would humans who have the same disease. Isomorphic animals share the same symptoms and treatments, only. Predictive models are similar to a particular human disease in only a couple of aspects. However, these are useful in isolating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepatitis B Virus
Hepatitis B virus (HBV) is a partially double-stranded DNA virus, a species of the genus '' Orthohepadnavirus'' and a member of the '' Hepadnaviridae'' family of viruses. This virus causes the disease hepatitis B. Classification Hepatitis B virus is classified in the genus '' Orthohepadnavirus'', which contains 11 other species. The genus is classified as part of the '' Hepadnaviridae'' family, which contains four other genera, '' Avihepadnavirus'', '' Herpetohepadnavirus'', '' Metahepadnavirus'' and '' Parahepadnavirus''. This family of viruses is the only member of the viral order ''Blubervirales''. Viruses similar to hepatitis B have been found in all apes (orangutans, gibbons, bonobos, gorillas and chimpanzees), in Old World monkeys, and in New World woolly monkeys (the woolly monkey hepatitis B virus), suggesting an ancient origin for this virus in primates. The virus is divided into four major serotypes (adr, adw, ayr, ayw) based on antigenic epitopes present on it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Synthesis
Protein biosynthesis, or protein synthesis, is a core biological process, occurring inside cells, balancing the loss of cellular proteins (via degradation or export) through the production of new proteins. Proteins perform a number of critical functions as enzymes, structural proteins or hormones. Protein synthesis is a very similar process for both prokaryotes and eukaryotes but there are some distinct differences. Protein synthesis can be divided broadly into two phases: transcription and translation. During transcription, a section of DNA encoding a protein, known as a gene, is converted into a molecule called messenger RNA (mRNA). This conversion is carried out by enzymes, known as RNA polymerases, in the nucleus of the cell. In eukaryotes, this mRNA is initially produced in a premature form (pre-mRNA) which undergoes post-transcriptional modifications to produce mature mRNA. The mature mRNA is exported from the cell nucleus via nuclear pores to the cytoplasm of the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Translation (biology)
In biology, translation is the process in living Cell (biology), cells in which proteins are produced using RNA molecules as templates. The generated protein is a sequence of amino acids. This sequence is determined by the sequence of nucleotides in the RNA. The nucleotides are considered three at a time. Each such triple results in the addition of one specific amino acid to the protein being generated. The matching from nucleotide triple to amino acid is called the genetic code. The translation is performed by a large complex of functional RNA and proteins called ribosomes. The entire process is called gene expression. In translation, messenger RNA (mRNA) is decoded in a ribosome, outside the nucleus, to produce a specific amino acid chain, or polypeptide. The polypeptide later protein folding, folds into an Activation energy, active protein and performs its functions in the cell. The polypeptide can also start folding during protein synthesis. The ribosome facilitates decoding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (biology)
Transcription is the process of copying a segment of DNA into RNA for the purpose of gene expression. Some segments of DNA are transcribed into RNA molecules that can encode proteins, called messenger RNA (mRNA). Other segments of DNA are transcribed into RNA molecules called non-coding RNAs (ncRNAs). Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a Complementarity (molecular biology), complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, Antiparallel (biochemistry), antiparallel RNA strand called a primary transcript. In virology, the term transcription is used when referring to mRNA synthesis from a viral RNA molecule. The genome of many Orthornavirae, RNA viruses is composed of Sense (molecular biology), negative-sense RNA which acts as a template for positive sense viral messenger RNA - a necessary step in the synthesis of viral proteins needed for viral replication. This process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (; : nuclei) is a membrane-bound organelle found in eukaryote, eukaryotic cell (biology), cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have #Anucleated_cells, no nuclei, and a few others including osteoclasts have Multinucleate, many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long strands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are Nuclear organization, structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Reading Frame
In molecular biology, reading frames are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames will be "open" (the "reading", however, refers to the RNA produced by transcription of the DNA and its subsequent interaction with the ribosome in translation). Such an open reading frame (ORF) may contain a start codon (usually AUG in terms of RNA) and by definition cannot extend beyond a stop codon (usually UAA, UAG or UGA in RNA). That start codon (not necessarily the first) indicates where translation may start. The transcription termination site is located after the ORF, beyond the translation stop codon. If transcription were to cease before the stop codon, an incomplete protein would be made during translation. In eukaryotic genes with multiple exons, introns are removed and exons are then joined together after transcription to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepadnaviridae
''Hepadnaviridae'' is a family of viruses. Humans, apes, and birds serve as natural hosts. The family contains five 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 yellow fever vaccine. The vaccine contained human serum as a stabilizing agent which was HBV ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Pair
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, "Watson–Crick" (or "Watson–Crick–Franklin") base pairs (guanine–cytosine and adenine–thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence. The Complementarity (molecular biology), complementary nature of this based-paired structure provides a Redundancy (information theory), redundant copy of the genetic information encoded within each strand of DNA. The regular structure and data redundancy provided by the DNA double helix make DNA well suited to the storage of genetic information, while base-pairing between DNA and incoming nucleotides provides the mechanism through which DNA polymerase replicates DNA and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genome
A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of junk DNA with no evident function. Almost all eukaryotes have mitochondrial DNA, mitochondria and a small mitochondrial genome. Algae and plants also contain chloroplast DNA, chloroplasts with a chloroplast genome. The study of the genome is called genomics. The genomes of many organisms have been Whole-genome sequencing, sequenced and various regions have been annotated. The first genome to be sequenced was that of the virus φX174 in 1977; the first genome sequence of a prokaryote (''Haemophilus influenzae'') was published in 1995; the yeast (''Saccharomyces cerevisiae'') genome was the first eukaryotic genome to be sequenced in 1996. The Human Genome Project ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
