Polyomavirus is the sole genus of viruses within the family Polyomaviridae. Polyomaviruses are DNA-based (double-stranded DNA,~5000 base pairs,circular genome), small (40-50 nanometers in diameter), and icosahedral in shape, and do not have a lipoprotein envelope. They are potentially oncogenic (tumor-causing); they often persist as latent infections in a host without causing disease, but may produce tumors in a host of a different species, or a host with an ineffective immune system. The name polyoma refers to the viruses' ability to produce multiple (poly-) tumors (-oma). In biology, a genus (plural genera) is a taxonomic grouping. ... The human immunodeficiency virus (HIV) A bacteriophage virus A virus is a submicroscopic parasitic particle that infects cells in biological organisms. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... A DNA virus is a virus that has DNA as its genetic material and does not use an RNA intermediate during replication. ... A nanometre (American spelling: nanometer) is 1. ... An icosahedron [ˌaıkəsəhiːdrən] noun (plural: -drons, -dra [-drə]) is a polyhedron having 20 faces, but usually a regular icosahedron is meant. ... A lipoprotein is a biochemical assembly that contains both proteins and lipids and may be structural or catalytic in function. ... An oncogenic process which is any tumor-forming process. ... Tumor (American English) or tumour (British English) originally means swelling, and is sometimes still used with that meaning. ... The immune system is the system of specialized cells and organs that protect an organism from outside biological influences. ...

There are two polyomaviruses found in humans: JC virus, which can infect the respiratory system, kidneys, or brain (sometimes causing the fatal progressive multifocal leukoencephalopathy in the latter case), and BK virus, which produces a mild respiratory infection and can affect the kidneys of immunosuppressed transplant patients. Both viruses are very widespread: approximately 80 percent of the adult population in the United States have antibodies to BK and JC. JC virus (JCV) or JC polyomavirus is a type of human polyomavirus, genetically similar to BK virus and SV40. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... Comparative brain sizes In animals, the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ... Progressive multifocal leukoencephalopathy (PML), also known as progressive multifocal leukoencephalitis, is a rare and usually fatal viral disease that is characterized by progressive damage (-pathy) or inflammation (-itis) of the white matter (leuko-) of the brain (-encephalo-) at multiple locations (multifocal). ... BK virus is a member of the polyomavirus family. ... An organ transplant is the transplantation of a whole or partial organ from one body to another (or from a donor site on the patients own body), for the purpose of replacing the recipients damaged or failing organ with a working one from the donor site. ...

The Simian vacuolating virus 40 replicates in the kidneys of monkeys without causing disease, but causes sarcomas in hamsters. It is unknown whether it can cause disease in humans, which has caused concern since the virus may have been introduced into the general population in the 1950s through a contaminated polio vaccine. SV40 is an abbreviation for Simian vacuolating virus 40 or Simian virus 40, a polyomavirus that is found in both monkeys and humans. ... Cynomolgus Monkey at Batu Caves, Malaysia Monkeys, Mori Sosen (1749-1821) A monkey is any member of two of the three groupings of simian primates. ... A sarcoma is a cancer of the bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. ... Genera Mesocricetus Phodopus Cricetus Cricetulus Allocricetulus Cansumys Tscherskia A hamster is a rodent belonging to subfamily Cricetinae. ... Two polio vaccines are used throughout the world to combat polio. ...

An avian polyomavirus sometimes referred to as the Budgerigar fledgling disease virus is a frequent cause of death among caged birds. For other meanings of bird, see bird (disambiguation). ...

The genus Polyomavirus used to be one of two genera within the now obsolete family Papovaviridae (the other genus being Papillomavirus which is now assigned to its own family Papillomaviridae). The name Papovaviridae derives from three abbreviations: Pa for Papillomavirus, Po for Polyomavirus, and Va for "vacuolating". Species See text Papillomaviruses are viruses that commonly cause warts. ... Species See text Papillomaviruses are viruses that commonly cause warts. ...

Replication

Polyomaviruses replicate in the nucleus of the host. They are able to utilise the host’s machinery because the genomic structure is homologous to that of the mammalian host. Viral replication occurs in two distinct phases; early and late gene expression, separated by genome replication. Nucleus usually refers to the center of something, but can mean: In science: Atomic nucleus, the collection of protons and neutrons in the center of an atom that carries the bulk of the atoms mass and positive charge Cell nucleus, the membrane-bound subcellular organelle found in eukaryotes, visible... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... In biology, two or more structures are said to be homologous if they are alike because of shared ancestry. ... Self-replication is the process by which some things make copies of themselves. ...

Early gene expression is responsible for the synthesis of non-structural proteins. Since Polyomaviruses rely on the host to control both the gene expression, the role of the non-structural proteins is to regulate the cellular mechanisms. Gene expression, also called protein expression or often simply expression is the process by which a genes DNA sequence is converted into the structures and functions of a cell. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

Genome replication acts to separate the early and late phase gene expression. The duplicated viral genome is synthesised and processed as if it was cellular DNA, exploiting the host’s machinery. As the daughter viral DNA are synthesised they associate with cellular nucleosomes to form structures that are often referred to as "minichromosomes". In this manner the DNA is packaged more efficiently. A nucleosome is a unit made of DNA and histones. ...

Late gene expression synthesises the structural proteins, responsible for the viral particle composition. This occurs during and after genome replication. As with the early gene expression products, late gene expression generates an array of proteins as a result of alternative splicing. Various modes of alternative splicing Alternative splicing is the process that occurs in eukaryotes in which the splicing process of a pre_mRNA can lead to different ripe mRNA molecules and therefore to different proteins. ...

External Links

• Polyomavirus at the University of Leicester

Species

• African green monkey polyomavirus (AGMPyV)
• Baboon polyomavirus 2 (PPyV)
• BK polyomavirus (BKPyV)
• Bovine polyomavirus (BPyV)
• Budgerigar fledgling disease virus (BFPyV)
• Hamster polyomavirus (HaPyV)
• JC polyomavirus (JCPyV)
• Murine pneumotropic virus (MPtV)
• Murine polyomavirus (MPyV)
• Rabbit kidney vacuolating virus (RKV)
• Simian virus 12 (SV-12)
• Simian virus 40 (SV-40, type species)