RESUMEN
The results of phylogenetic analysis of three species of bovine pestiviruses circulating in six regions of Siberia, as well as those detected in fetal embryonic serum (FBS) and continuous cell cultures, are presented. The typing was made based on comparison of sequences from the 5' untranslated region (5'-UTR) of the viral genome. Among the highly productive dairy cattle, circulation of five subtypes of the BVDV1 (a, b, d, f, r) and BVDV2 was established. The predominant subtype was 1b (48% positive samples). The number of subtypes of BVDV1 was as follows: BVDV1: 1а (8%), 1b (48%), 1d (8%), 1f (16%) и 1r (8%) and BVDV2 (12%). Cell cultures revealed BVDV1a. The distribution of types and subtypes of viruses had geographical differences. BVDV1b, BVDV1d, BVDV1f и BVDV1r were detected in cattle or persistently infected (PI) animals in farms with respiratory distress. BVDV 1a revealed in the serum of PI heifer without manifestation of clinical symptoms. BVDV2 were detected in cattle with pathology of reproduction. The presence of the BVDV3 (atypical pestivirus) of the Italian group was established in seven lots of FBS obtained from two manufacturers. No evidence has been found for circulating of the atypical virus among cattle of various breeds, including imported, reindeers and red deers. Studies on the molecular epizootology of pestiviruses can be used to select and optimize the control strategy and address the issue of vaccine use in a particular region.
RESUMEN
The review presents the latest data about the types of vaccines against avian influenza that are used in current medical practice or are under development. Inactivated whole virion vaccines, live vector vaccines, as well as experimental vaccines developed using genetic engineering techniques (e.g. subunit vaccines, VLP vaccines, DNA vaccines) were considered. The efficiency of influenza reverse genetic technology for the development of prototype vaccine strains was noted.