Pestivirus is a genus of viruses, in the family Flaviviridae. Viruses in the genus Pestivirus infect mammals, including members of the family Bovidae (which includes cattle, sheep, and goats) and the family Suidae (which includes various species of swine). There are 11 species in this genus. Diseases associated with this genus include: hemorrhagic syndromes, abortion, and fatal mucosal disease. Structure Viruses in Pestivirus are enveloped, with spherical geometries. Their diameter is around 50 nm. Genomes are linear and not segmented, around 12kb in length. Lifecycle Entry into the host cell is achieved by attachment of the viral envelope protein E2 to host receptors, which mediates clathrin-mediated endocytosis. The main viral replication process happens in host cytoplasm. Replication follows the positive strand RNA virus replication model. An IRES RNA element at the 5'-nontranslated region (NTR) of the viral genome recruits viral and cellular translation factors to initiate viral protein translation. Viral proteins are first translated as polyprotein, and then processed into individual structure and non-structure proteins by both viral and host proteases. The virus exits the host cell by budding. Mammals serve as the natural hosts.When infected, the host sheds viruses in almost all body secretions including saliva, nasal discharge, milk, and feaces. Vertical transmission (viruses crossing the placenta and infecting the fetus) are also common. Genome Pestivirus viruses have a single strand of positive-sense RNA (i.e. RNA which can be directly translated into viral proteins) that is around 12.5 kilobases (kb) long (equal to the length of 12,500 nucleotides), but due to recombination events has been observed up to 16.5 kilobases in length. Sometimes, virions (individual virus particles) contain sections of an animal's genome that have been duplicated, though this is not normally the case. Although lacking Poly-A tail at the 3' end of the genome, it contains stem-loop regions that might be involved in viral translation and replication. The genome contains RNA to encode both structural and nonstructural 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 A 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