PESTIVIRUSES, WHICH CONTAMINATE IMPORTED FETAL BOVINE SERUM, MAY BE A CAUSE OF THE GLOBAL SPREADING OF VIRAL DIARRHEA IN CATTLE - A MINI REVIEW
Pestiviruses are an important cause of economic losses in the dairy and beef industry. Diseases caused by them are common around the world with varying prevalence associated with the features of regional strategy of livestock including in Russia (A.G. Glotov et al., 2002; M.I. Gulyukin et al., 2013; J.F. Ridpath, 2010). The bovine viral diarrhea virus is considered as a prototype member of the genus Pestivirus, Flaviviridae family. Two distinct viruses designated as BVDV1 and BVDV2 cause the disease in cattle. A candidate member of the genus is BVDV3, the atypical and not classified pestivirus which shows high similarity to BVDV1 and BVDV2. The BVDV3 presence in the cattle population can compromise BVDV control or eradication (F.V. Bauermann, 2013). This virus requires special attention. BVDV was isolated from commercial lots of fetal bovine serum used for cell culture and biologicals, and is dangerous because of possible spread to new regions (H. Schirrmeier et al., 2004). Viruses of this genus are contaminants of fetal serum, continuous cell line cultures, human and animal vaccines, interferons, trypsin, embryos, stem cells, etc. (B. Makoschey et al., 2003; S.Q. Zhang et al., 2014). Because of globalization and rapid development of cell biotechnology in veterinary and human medicine, the demand for fetal bovine serum, which is a by-product of beef industry, is annually increasing (G. Gstraunthaler et al., 2013). OIE has established product quality standards and regulations according to which all the cell cultures intended to use must be tested for the absence of the virus and its RNA in some passages. Blood serum including fetal serum must be free of the virus and also of the specific antibodies thereto (OIE, 2015). These requirements should also apply to BVDV3. The lack of fetal bovine serum production in Russia creates the possible risk of lots from foreign manufacturers of questionable quality. Special scholar publications report on cases of contamination of different cell cultures and sera by noncytopathic BVDV strains in Russia (S.V. Alekseenkova et al., 2013). The live vaccines prepared using low-quality raw materials can be a potential source of virus for susceptible animals, and contaminated diagnostic antigens can cause false results of the study. Thence, more strict control is extremely important to prevent biological contamination of vaccines and other biologicals.