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Polyomavirus
''Polyomaviridae'' is a family of viruses whose natural hosts are primarily mammals and birds. As of 2020, there are six recognized genera and 117 species, five of which are unassigned to a genus. 14 species are known to infect humans, while others, such as Simian Virus 40, have been identified in humans to a lesser extent. Most of these viruses are very common and typically asymptomatic in most human populations studied. BK virus is associated with nephropathy in renal transplant and non-renal solid organ transplant patients, JC virus with progressive multifocal leukoencephalopathy, and Merkel cell virus with Merkel cell cancer. Structure and genome Polyomaviruses are non-enveloped double-stranded DNA viruses with circular genomes of around 5000 base pairs. The genome is packaged in a viral capsid of about 40-50 nanometers in diameter, which is icosahedral in shape (T=7 symmetry). The capsid is composed of 72 pentameric capsomeres of a protein called VP1, which is capabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merkel Cell Virus
Merkel cell polyomavirus (MCV or MCPyV) was first described in January 2008 in Pittsburgh, Pennsylvania. It was the first example of a human viral pathogen discovered using unbiased metagenomic next-generation sequencing with a technique called digital transcriptome subtraction. MCV is one of seven currently known human oncoviruses. It is suspected to cause the majority of cases of Merkel cell carcinoma, a rare but aggressive form of skin cancer. Approximately 80% of Merkel cell carcinoma (MCC) tumors have been found to be infected with MCV. MCV appears to be a common—if not universal—infection of older children and adults. It is found in respiratory secretions suggesting that it may be transmitted by a respiratory route. But it also can be found shedding from healthy skin, and in gastrointestinal tract tissues and elsewhere, and so its precise mode of transmission remains unknown. In addition, recent studies suggest that this virus may latently infect the human sera and peri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simian Virus 40
SV40 is an abbreviation for simian vacuolating virus 40 or simian virus 40, a polyomavirus that is found in both monkeys and humans. Like other polyomaviruses, SV40 is a DNA virus that has the potential to cause tumors in animals, but most often persists as a latent infection. SV40 has been widely studied as a model eukaryotic virus, leading to many early discoveries in eukaryotic DNA replication and transcription. Human disease The hypothesis that SV40 might cause cancer in humans has been a particularly controversial area of research. It is currently unclear whether SV40 has any role in causing tumors. As a result of these uncertainties, academic opinion remains divided, with some arguing that this hypothesis is not supported by the data and others arguing that some cancers may involve SV40. The US National Cancer Institute announced in 2004 that although SV40 does cause cancer in some animal models, "substantial epidemiological evidence has accumulated to indicate that SV40 l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merkel Cell Cancer
Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer occurring in about 3 people per 1,000,000 members of the population. It is also known as cutaneous APUDoma, primary neuroendocrine carcinoma of the skin, primary small cell carcinoma of the skin, and trabecular carcinoma of the skin. Factors involved in the development of MCC include the Merkel cell polyomavirus (MCPyV or MCV), a weakened immune system, and exposure to ultraviolet radiation. Merkel-cell carcinoma usually arises on the head, neck, and extremities, as well as in the perianal region and on the eyelid. It is more common in people over 60 years old, Caucasian people, and males. MCC is less common in children. Signs and symptoms Merkel cell carcinoma (MCC) usually presents as a firm nodule (up to 2 cm diameter) or mass (>2 cm diameter). These flesh-colored, red, or blue tumors typically vary in size from 0.5 cm (less than one-quarter of an inch) to more than 5 cm (2 inches) in diame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minor Capsid Proteins VP2 And VP3
Minor capsid protein VP2 and minor capsid protein VP3 are viral proteins that are components of the polyomavirus capsid. Polyomavirus capsids are composed of three proteins; the major component is major capsid protein VP1, which self-assembles into pentamers that in turn self-assemble into enclosed icosahedral structures. The minor components are VP2 and VP3, which bind in the interior of the capsid. Gene expression All three capsid proteins are expressed from alternative start sites on a single transcript of the "late region" of the circular viral chromosome (so named because it is transcribed late in the process of viral infection). The VP3 start site is in frame downstream from that of VP2; in consequence VP3's sequence is identical to the C-terminal portion of VP2, which has an additional N-terminal extension. In at least some polyomaviruses, the VP2 N-terminus is myristoylated. Some members of the polyomavirus family, such as Merkel cell polyomavirus, do not appear to enco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Progressive Multifocal Leukoencephalopathy
Progressive multifocal leukoencephalopathy (PML) is a rare and often fatal viral disease characterized by progressive damage (''-pathy'') or inflammation of the white matter (''leuko-'') of the brain (''-encephalo-'') at multiple locations (''multifocal''). It is caused by the JC virus, which is normally present and kept under control by the immune system. The JC virus is harmless except in cases of weakened immune systems. In general, PML has a mortality rate of 30–50% in the first few months, and those who survive can be left with varying degrees of neurological disabilities. PML occurs almost exclusively in patients with severe immune deficiency, most commonly among patients with acquired immune deficiency syndrome (AIDS), but people on chronic immunosuppressive medications including chemotherapy are also at increased risk of PML, such as patients with transplants, Hodgkin's lymphoma, multiple sclerosis, psoriasis, rheumatoid arthritis, and other autoimmune diseases. Sign ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyomavirus Capsid Protein (VP1)
Major capsid protein VP1 is a viral protein that is the main component of the polyomavirus capsid. VP1 monomers are generally around 350 amino acids long and are capable of self-assembly into an icosahedral structure consisting of 360 VP1 molecules organized into 72 pentamers. VP1 molecules possess a surface binding site that interacts with sialic acids attached to glycans, including some gangliosides, on the surfaces of cells to initiate the process of viral infection. The VP1 protein, along with capsid components VP2 and VP3, is expressed from the "late region" of the circular viral genome. Structure VP1 is the major structural component of the polyomavirus icosahedral capsid, which has T=7 symmetry and a diameter of 40-45 nm. The capsid contains three proteins; VP1 is the primary component and forms a 360-unit outer capsid layer composed of 72 pentamers. The other two components, VP2 and VP3, have high sequence similarity to each other, with VP3 truncated at the N-term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viral Envelope
A viral envelope is the outermost layer of many types of viruses. It protects the genetic material in their life cycle when traveling between host cells. Not all viruses have envelopes. Numerous human pathogenic viruses in circulation are encased in lipid bilayers, and they infect their target cells by causing the viral envelope and cell membrane to fuse. Although there are effective vaccines against some of these viruses, there is no preventative or curative medicine for the majority of them. In most cases, the known vaccines operate by inducing antibodies that prevent the pathogen from entering cells. This happens in the case of enveloped viruses when the antibodies bind to the viral envelope proteins. The membrane fusion event that triggers viral entrance is caused by the viral fusion protein. Many enveloped viruses only have one protein visible on the surface of the particle, which is required for both mediating adhesion to the cell surface and for the subsequent membrane fusi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaynor Plospathogens 2007 WUvirusgenome
Gaynor is both a surname and a given name. Notable people with the name include: Surname * Adam Gaynor (born 1963), American guitarist * Barrington Gaynor (1965–2011), Jamaican footballer * Ciara Gaynor (born 1979), Irish camogie player * Dave Gaynor, English drummer * Gloria Gaynor (born 1943), American singer * Janet Gaynor (1906–1984), American actress * Jessie Gaynor (1863–1921), American composer * John A. Gaynor (1846–1915), American politician * Katie Gaynor (born 1977), Australian baseball player * Len Gaynor (born 1944), Irish hurling manager * Len Gaynor (footballer) (born 1949), English footballer * Mel Gaynor (born 1960), British musician * Mitzi Gaynor (born 1931), American actress, singer and dancer * Pete Gaynor (born 1958), U.S. Administrator of FEMA * Ross Gaynor (born 1987), Irish footballer * Tomas Gaynor (born 1991), Australian rapper, singer and songwriter, known professionally as Allday * Tommy Gaynor (born 1963), Irish footballer * William Jay Gayn ... [...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 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 RNA polymerase transcribes DNA in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capsomere
The capsomere is a subunit of the capsid, an outer covering of protein that protects the genetic material of a virus. Capsomeres self-assemble to form the capsid. Subunits called protomers aggregate to form capsomeres. Various arrangements of capsomeres are: 1) Icosahedral, 2) Helical, and 3) Complex. 1) Icosahedral- An icosahedron is a polyhedron with 12 vertices and 20 faces. Two types of capsomeres constitute the icosahedral capsid: pentagonal (pentons) at the vertices and hexagonal ( hexons) at the faces. There are always twelve pentons, but the number of hexons varies among virus groups. In electron micrographs, capsomeres are recognized as regularly spaced rings with a central hole. 2) Helical- The protomers are not grouped in capsomeres, but are bound to each other so as to form a ribbon-like structure. This structure folds into a helix because the protomers are thicker at one end than at the other. The diameter of the helical capsid is determined by characteristics of i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Icosahedral
In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes and . The plural can be either "icosahedra" () or "icosahedrons". There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrical than others. The best known is the (convex, non- stellated) regular icosahedron—one of the Platonic solids—whose faces are 20 equilateral triangles. Regular icosahedra There are two objects, one convex and one nonconvex, that can both be called regular icosahedra. Each has 30 edges and 20 equilateral triangle faces with five meeting at each of its twelve vertices. Both have icosahedral symmetry. The term "regular icosahedron" generally refers to the convex variety, while the nonconvex form is called a ''great icosahedron''. Convex regular icosahedron The convex regular icosahedron is usually referred to simply as the ''regular icosahedron'', one of the five regular Platonic solids, and is represented by its Schläfli symbol , co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
