Porcine transmissible gastroenteritis virus

Synonym for Transmissible gastroenteritis virus.

Porcine type C oncovirus (PCOV) A species in the genus Gammaretrovirus. Identified in a cell line, originating from a lymph node of a leukemic pig, after treatment with 5-bromodeoxyuridine and dimethyl sulfoxide. The porcine lymphoma cell particle (PLCP) is serologically distinct from mouse and cat oncoviruses but contains mammalian interspecies antigen B only. It is thus more like Woolly monkey and Gibbon ape leukemia viruses than the cat and mouse oncoviruses. It is endogenous and the DNA sequences are present in the cellular DNA of domestic pigs and other species of the family Suidae.

porcupine parvovirus The investigation into the deaths of six porcupines over a 142-day period, showed histological findings indicative of parvovirus infection. However, electron microscopy, serology and virological studies failed to demonstrate parvovirus as the etiologi-cal agent.

Frelier PF et al (1984) J Am Vet Med Assoc 185, 1291

porpoise distemper virus A strain of Cetacean morbillivirus, in the genus Morbillivirus, first identified in 1988 in harbor porpoises, Phocoena phocoena, in the North Sea. Closely related genetically to dolphin morbillivirus.

Bolt G et al (1994) Virus Res 34, 291 Kennedy S (1998) J Comp Pathol 119, 201

Portillo virus A possible species in the genus Arenavirus. A member of the Tacaribe serogroup, and closely related antigenically to Junin virus. Has been isolated from infants in Buenos Aires with hemolytic-uremic disease.

Porton virus (PORV) A tentative species in the genus Vesiculovirus. Isolated from mosquitoes, Mansonia uniformis in Malaysia. Not reported to cause disease in humans.

positive strand One of the two possible RNA strands. The one which functions as mRNA is known as the 'positive strand': the complementary strand is called the 'negative strand'. See genome. Synonym: plus strand.

possum papillomavirus A possible species in the genus Papillomavirus identified by electron microscopy and PCR analysis of epithelial tissues from a brushtail possum, Trichosurus vulpecula. Phylo-genetic analysis suggests that this is a new papillomavirus.

Perrott MR et al (2000) Arch Virol 145, 1247

post-polio syndrome A rare condition in which persons who have survived an initial attack of poliomyelitis suffer a degeneration of function many years later. Infectious virus cannot be isolated. Sequences of poliovirus-related RNA have been detected in the CSF in such cases, which may indicate that the virus can persist in neural cells, but this is not proven.

Stone R (1994) Science 264, 909

post-transcriptional modification Alterations in the structure of RNA transcripts prior to utilization as mRNA. These may include splicing, capping with a blocked methylated structure at the 5' end, addition of poly A at the 3' end, or methylation of certain bases internally in the RNA, particularly adenylic and cytidylic acids. These modifications all occur in most species of eukaryotic cell mRNA, and are apparently accomplished by enzymes in the cell nucleus. Viral RNA transcripts synthesized within the cell nucleus (e.g. Orthomyxoviridae, Retroviridae, Papovaviridae, Adenoviridae and Herpesviridae) may be modified by these cell enzymes. Viruses replicating wholly in the cytoplasm (e.g. Paramyxoviridae, Rhabdoviridae, Picorna-viridae, Togaviridae and Poxviridae) carry similar enzymes in the virion or induce their synthesis in infected cells.

post-translational cleavage Division of a large protein molecule (polyprotein) after translation from the viral genome. The polyprotein is cleaved at specific sites to produce smaller functional proteins; this may involve a series of cleavages as with human poliovirus. Post-translational cleavage is a necessary feature of the replication of positive-strand RNA viruses, since it appears that eukaryotic ribosomes only recognize one initiation site on these polycistronic genomes. Most other viruses induce the formation of monocistronic mRNAs during replication, so that functional proteins may be formed directly. Cleavage may also occur within the assembled virion. Cleavage of the surface glycoproteins appears to increase virulence in the case of Paramyxoviridae.

Ehrenfeld E (1993) Semin Virol 4, 199

post-translational modification A variety of different modifications have been found to occur after translation of a viral protein, for reasons that are not fully understood. These include cleavage into smaller fragments, glycosylation, phos-phorylation, prenylation and myristylation.

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