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Capsid
A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The proteins making up the capsid are called capsid proteins or viral coat proteins (VCP). The capsid and inner genome is called the nucleocapsid. Capsids are broadly classified according to their structure. The majority of the viruses have capsids with either helical or icosahedral structure. Some viruses, such as bacteriophages, have developed more complicated structures due to constraints of elasticity and electrostatics. The icosahedral shape, which has 20 equilateral triangular faces, approximates a sphere, while the helical shape resembles the shape of a spring, taking the space of a cylinder but not being a cylinder itself. The capsid faces may consist of one or m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 capable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foot-and-mouth Disease
Foot-and-mouth disease (FMD) or hoof-and-mouth disease (HMD) is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, including domestic and wild bovids. The virus causes a high fever lasting two to six days, followed by blisters inside the mouth and near the hoof that may rupture and cause lameness. FMD has very severe implications for animal farming, since it is highly infectious and can be spread by infected animals comparatively easily through contact with contaminated farming equipment, vehicles, clothing, and feed, and by domestic and wild predators. Its containment demands considerable efforts in vaccination, strict monitoring, trade restrictions, quarantines, and the culling of both infected and healthy (uninfected) animals. Susceptible animals include cattle, water buffalo, sheep, goats, pigs, antelope, deer, and bison. It has also been known to infect hedgehogs and elephants; llamas and alpacas may develop mild symptoms, but are res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mimivirus
''Mimivirus'' is a genus of giant viruses, in the family '' Mimiviridae''. Amoeba serve as their natural hosts. This genus contains a single identified species named ''Acanthamoeba polyphaga mimivirus'' (APMV). It also refers to a group of phylogenetically related large viruses. In colloquial speech, APMV is more commonly referred to as just "mimivirus". Mimivirus, short for "mimicking microbe", is so called to reflect its large size and apparent Gram-staining properties. Mimivirus has a large and complex genome compared with most other viruses. Until 2013, when a larger virus '' Pandoravirus'' was described, it had the largest capsid diameter of all known viruses. History APMV was discovered accidentally in 1992 within the amoeba '' Acanthamoeba polyphaga'', after which it is named, during research into legionellosis by researchers from Marseille and Leeds. The virus was observed in a Gram stain and mistakenly thought to be a Gram-positive bacterium. As a consequence it was ... [...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] |
Chlorovirus
''Chlorovirus'', also known as Chlorella virus, is a genus of giant double-stranded DNA viruses, in the family '' Phycodnaviridae''. This genus is found globally in freshwater environments where freshwater microscopic algae serve as natural hosts. There are 19 species in this genus. ''Chlorovirus'' was initially discovered in 1981 by Russel H. Meints, James L. Van Etten, Daniel Kuczmarski, Kit Lee, and Barbara Ang while attempting to culture Chlorella-like algae. During the attempted process viral particles were discovered in the cells 2 to 6 hours after being initially isolated, followed by lysis after 12 to 20 hours. This virus was initially called HVCV (Hydra viridis Chlorella virus) since it was first found to infect Chlorella-like algae. Though relatively new to virologists and thus not extensively studied, one species, Chlorovirus ATCV-1, commonly found in lakes, has been recently found to infect humans. New studies focusing on effects of infection in mouse model are curr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacteriophage
A bacteriophage (), also known informally as a ''phage'' (), is a duplodnaviria virus that infects and replicates within bacteria and archaea. The term was derived from "bacteria" and the Greek φαγεῖν ('), meaning "to devour". Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have structures that are either simple or elaborate. Their genomes may encode as few as four genes (e.g. MS2) and as many as hundreds of genes. Phages replicate within the bacterium following the injection of their genome into its cytoplasm. Bacteriophages are among the most common and diverse entities in the biosphere. Bacteriophages are ubiquitous viruses, found wherever bacteria exist. It is estimated there are more than 1031 bacteriophages on the planet, more than every other organism on Earth, including bacteria, combined. Viruses are the most abundant biological entity in the water column of the world's oceans, and the second largest component o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus Capsid T Number
A virus is a submicroscopic infectious agent that replicates only inside the living 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'', consisting of (i) the genetic material, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Papillomaviruses
''Papillomaviridae'' is a family of non- enveloped DNA viruses whose members are known as papillomaviruses. Several hundred species of papillomaviruses, traditionally referred to as "types", have been identified infecting all carefully inspected mammals, but also other vertebrates such as birds, snakes, turtles and fish. Infection by most papillomavirus types, depending on the type, is either asymptomatic (e.g. most Beta-PVs) or causes small benign tumors, known as papillomas or warts (e.g. human papillomavirus 1, HPV6 or HPV11). Papillomas caused by some types, however, such as human papillomaviruses 16 and 18, carry a risk of becoming cancerous. Papillomaviruses are usually considered as highly host- and tissue- tropic, and are thought to rarely be transmitted between species. Papillomaviruses replicate exclusively in the basal layer of the body surface tissues. All known papillomavirus types infect a particular body surface, typically the skin or mucosal epithelium of the g ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goldberg Polyhedra
In mathematics, and more specifically in polyhedral combinatorics, a Goldberg polyhedron is a convex polyhedron made from hexagons and pentagons. They were first described in 1937 by Michael Goldberg (1902–1990). They are defined by three properties: each face is either a pentagon or hexagon, exactly three faces meet at each vertex, and they have rotational icosahedral symmetry. They are not necessarily mirror-symmetric; e.g. and are enantiomorphs of each other. A Goldberg polyhedron is a dual polyhedron of a geodesic sphere. A consequence of Euler's polyhedron formula is that a Goldberg polyhedron always has exactly twelve pentagonal faces. Icosahedral symmetry ensures that the pentagons are always regular and that there are always 12 of them. If the vertices are not constrained to a sphere, the polyhedron can be constructed with planar equilateral (but not in general equiangular) faces. Simple examples of Goldberg polyhedra include the dodecahedron and truncated icosah ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
A virus is a submicroscopic infectious agent that replicates only inside the living 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'', consisting of (i) the genetic mate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Donald Caspar
Donald L. D. Caspar (January 8, 1927 - November 27, 2021) was an American structural biologist (the very term he coined) known for his works on the structures of biological molecules, particularly of the tobacco mosaic virus. He was an emeritus professor of biological science at the Institute of Molecular Biophysics, Florida State University, and an emeritus professor of biology at the Rosenstiel Basic Medical Sciences Research Center, Brandeis University. He has made significant scientific contributions in virus biology, X -ray, neutron and electron diffraction, and protein plasticity. Caspar completed his BA in physics from Cornell University in 1950. He joined Yale University from where he earned his PhD in biophysics in 1955. He was supervised by Ernest C. Pollard. His thesis was on the structure of tobacco mosaic virus (TMV) titled ''The Radial Structure of Tobacco Mosaic Virus''. While waiting for his degree he worked under Max Delbrück at the California Institute of Tec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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