LAUSR

The genetic characterization of bovine leukemia virus (BLV) is an important task in scientific research in many countries of the world. According to the sequenced gene region env BLV isolates have been found in different geographical locations of the world, and up to 10 different genetic groups of the virus have been identified and classified. As part of the research, we monitored the epizootic situation of the BLV in Russia. For grouping of animals (n = 54) Holstein-Frisian (imported breed) and Russian Black Pied (local breed) were selected, belonging to agricultural organizations in the Tyumen region. Serological screening methods (ELISA, AGID) were used in the cattle to identify infected animals. Immunological evaluation of the animals in all the test groups was also done. A primary A nested-PCR study was performed, which resulted in a fragment of the env 444 bp gene in the studied samples. RFLP analysis of this fragment established that in 94% of the samples there was the «Belgian type» of the leukemia virus, in 4% of samples the «Australian» type, and in 2% a «mixed type». The phylogenetic evaluation of the BLV genome env site in the isolated samples and the immunological evaluation of the infected animals helped to obtain new data that will enable information on the genetic groups of the BLV in the territory of the Russian Federation to be updated. key words: bovine leukemia virus; cattle; phylogenetic classification; serological screening; polymerase chain reaction; epizootic monitoring ________________________________________________________________________________________