|Group:||Group IV ((+)ssRNA)|
|Bovine viral diarrhoea virus 1
Pestivirus is a genus of viruses that belong to the family Flaviviridae. Viruses in the genus Pestivirus infect mammals, including members of the family Bovidae (which includes, but is not limited to, cattle, sheep, and goats) and the family Suidae (which includes various species of swine).
Virus Genetics and Structure
Pestivirus viruses have a single strand of positive-sense RNA (i.e. RNA which can be directly translated into viral proteins) which is around 12.5 kilobases (kb) long (equal to the length of 12,500 nucleotides). Sometimes virions (individual virus particles) contain sections of an animal's genome which have been duplicated, though this is not normally the case. There is no Poly-A on the 3' end of the genome. (This means that these viruses have no post-transcriptional modifications, and have simple RNA genomes.) The genome contains RNA to encode both structural and non-structural proteins. The molecular biology of pestiviruses shares many similarities and peculiarities with the human hepaciviruses. Genome organisation and translation strategy are highly similar for the members of both genera. For BVDV frequently nonhomologous RNA recombination events lead to the appearance of genetically distinct viruses that are lethal to the host.
Transmission and Prevention
Pestivirus is widespread in Australia, mainly in cattle. Some adult cattle are immune to the disease, while others are lifelong carriers. If a foetus becomes infected within the first three to four months of gestation then it will fail to develop antibodies towards the virus. In these cases the animals often die before birth or shortly after. It is spread very easily among feedlot cattle as nasal secretions and close contact spread the disease, and animals with infected mucous membranes give off millions of particles of BVDV a day.
Pestivirus vaccines exist and the correct vaccine strain should be given, depending on the herd's location and the endemic strain in that region. This vaccination must be given regularly to maintain immunity.
Several additional isolates have been reported and may be recognised as species
- Border disease virus 2 (BDV-2)
- Bovine viral diarrhoea virus 3 (BVDV-3) (HoBi group)