Phylogeny, classification and evolutionary insights into pestiviruses.

The genus Pestivirus comprises four established species: Bovine viral diarrhoea viruses 1 (BVDV-1) and 2 (BVDV-2), Border disease virus (BDV), and Classical swine fever virus (CSFV); and a tentative species, Pestivirus of giraffe. Additional pestiviruses have been identified and suggested for recognition as novel subgroups/species. To achieve a reliable phylogeny as the basis for classification of pestiviruses, a molecular dataset of 56 pestiviruses and 2089 characters, comprising the 5'UTR, complete N(pro) and E2 gene regions was analysed by Maximum likelihood and Bayesian approach. An identical, robust tree topology was inferred, where seven well-supported monophyletic clades and two highly divergent lineages were identified. Dating most recent common ancestor was estimated for major pestivirus lineages and their evolutionary histories were revealed. Accordingly, a new proposal is presented for the classification of pestiviruses into nine species: BVDV-1, BVDV-2, BVDV-3 (atypical bovine pestiviruses), Pestivirus of giraffe, CSFV, BDV, Tunisian sheep virus (TSV; previously termed "Tunisian isolates"), Antelope and Bungowannah.