ATYPICAL BOVINE PESTIVIRUSES (review)

Increasingly frequent outbreaks of atypical viral infections, detection of new viruses, modified isolates and quasispecies with a confirmed or potential emergence have become a worrying feature of the last decades characterized by extremely close international dealings.For the cattle industry, they pose real and serious threat because of a tendency to spread widely and quickly due to globalization and the use of standardized zootechnical and veterinary protocols.The Flaviviridae family comprises several genera of which the genus Pestivirus, including four viruses, i.e. the cattle viral diarrhea -mucosal disease (VD-MD) virus types 1 and 2, swine fever virus and sheep border disease virus, are important to farm animals (http://ictvonline.org/virusTaxonomy.asp).The characteristics of a new group of viruses genus Pestivirus of the Flaviviridae family, allocated in the period from 2000 to 2014 from the buffalo and cattle, as well as fetal calf serum used for cell cultures and vaccines production harvested in Australia, Canada, Mexico, Brazil and the United States and packaged in Europe (H.Schirrmeier et al., 2004; A. Cortez et al., 2006; E. Bianchi et al., 2011; B. Rodrigues et al., 2011; H. Xia et al., 2011; H. Xia et al., 2012; S. Peletto et al., 2012) are submitted in the review.The virus has been isolated in Thailand, Bangladesh and China (L.Liu et al., 2009; L. Mao et al., 2012; N. Haider et al., 2014).Messages on the isolation of the agent in other European countries, North America, Russia, India and Australia are absent (F.V. Bauermann et al., 2013).The widespread use of contaminated biological products can facilitate the penetration of the virus in different regions of continent causing their potential emergence for cattle.Strains of viruses presented cytopathogenic and non-cytopathogenic biotypes not officially classified and have a variety titles in literature: a third type of viral diarrhea-mucosal disease in cattle (BVDV), an atypical pestivirus (HoBi-like), the fifth type of Pestivirus genus (N.Decaro et al., 2012).Based on phylogenetic analysis were identified two genetic groups: Brazilian and Thai, which differ from the prototype member of the genus -the BVD virus but having a great similarity in the manifestation of clinical signs, the ability to infect the foetus of cattle and buffalo (F.V. Bauermann et al., 2013).In cattle a spontaneous or experimental infection caused by HoBi-like virus is very similar to the cattle VD-MD and manifests as diarrhea, abortion, respiratory syndrome, persistent infection (F.V. Bauermann et al., 2013).The situation is aggravated by the fact that they like the BVDV are able to induce persistent infection and forms permanent epizootic foci (M.N.Weber et al., 2014).The discovery of this group of viruses requires a critical assessment of the diagnostic tools and vaccines against the BVDV.To date, the there are no tests for the detection of ruminants' pestiviruses or their antibodies, particularly due to high variability of this virus group.That is why their laboratory diagnosis should not rely on the use of a single test.The best approach would be serological diagnosis of the herd followed by the identification of persistently infected animals, the virus isolation and molecular analysis (F.V. Bauermann et al., 2013).Given the lack of HoBi-like infection diagnostics, these viruses can remain unnoticed and, presumably, compromising the effectiveness of control or eradication programs of BVDV realized in certain European countries and the United States (K.Ståhl et al., 2004; J.F. Ridpath, 2010).

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