Recent studies have shown that bovine leukemia virus (BLV) sequences can be classified into seven distinct genotypes based on full gp51 sequence. This classification was based on available sequence data that mainly represented the BLV population that is circulating in cattle from the US and South America. In order to aid with a global perspective inclusion of data from Eastern Europe is required. In this study we examined 44 BLV isolates from different geographical regions of Poland, Belarus, Ukraine, and Russia. Phylogenetic analysis based on a 444bp fragment of env gene revealed that most of isolates belonged to genotypes 4 and 7. Furthermore, we confirmed the existence of a new genotype, genotype 8, which was highly supported by phylogenetic computations. A significant number of amino acid substitutions were found in the sequences of the studied Eastern European isolates, of which 71% have not been described previously. The substitutions encompassed mainly the C-part of the CD4+ epitope, zinc binding peptide region, CD8+ T cell epitope, and overlapping linear epitope E. These observations highlight the use of sequence data to both elucidate phylogenetic relationships and the potential effect on serological detection of geographically diverse isolates.

The aim of the research is the use of serological and molecular genetic methods for detecting virus-infected cattle leukemia, as well as determining the significance of PCR in identifying BLV infected calves in the system of antiepizootic health measures. The developed technique for early diagnosis of leukemia in cattle made it possible to accelerate the process of recovery of disadvantaged farms in the Belgorod region by increasing the frequency of studies from 6 months to 2-3 months and an increase in the sensitivity of the agar-gel immunodiffusion test. This, in turn, leads to an increase in the sensitivity of the agar-gel immunodiffusion test and makes it possible to detect, on average, from 8.8% to 20.25% more animals infected with the leukemia virus compared to the standard reaction of the agar-gel immunodiffusion test. The additional use of molecular genetic tests for the detection of proviral DNA of the leukemia virus makes it possible to identify at the early stages of the development of the leukemia process, in calves from 15 days of age, the genomic material of bovine leukemia virus, which will also allow in a shorter time to carry out a qualitative improvement of young cattle in dysfunctional farms.

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PEtRoPavlovskIy, M., I. DoNNIk, N. BEzBoRoDova: Epizootiological and genetic characterization of the bovine leukemia virus in the Russian federation-evaluation of bovine leukemia virus in Russia. vet. arhiv 89, 785-798, 2019.

Leukemia in animals is a serious disease of the cancer naturethe hemoblastosis, the etiologic factor of which is the bovine leukemia virus belonging to the family Retroviridae, the genus Deltaretrovirus. The causative agent is widely spread all over the world, including the Russian Federation. The main symptom of the disease is the malignant proliferation of cells of the hematopoietic organs with a violation of their maturation. Developing quantitative and qualitative disorders of the hematopoietic system are noted in the diseased organism. This paper presents data on the effects of leukemia virus on the process of hematopoiesis in cattle in the conditions of the Ural region. Infected animals of the Tyumen region were identified by serological studies (RID, ELISA) and molecular genetic studies (PCR) of isolates of bovine leukemia virus. The RFLP method established the predominant presence of the "Belgian genotype" in the samples. The env (glycoprotein envelope) gene of leukemia pathogen was sequenced. The immunehematological studies of cattle, infected with leukemia virus in the conditions of the Ural region, were conducted. The obtained data showed a significant increase in the number of leukocytes, lymphocytes in the blood of leukemic animals, a sharp decrease in the number of eosinophils, monocytes, CIC (circulating immune complexes), phagocytosis, T and B lymphocytes.