New mutations of env gene and its impact on virulence properties for Bovine leukemia virus

This study is the biodiversity and properties of bovine leukemia virus in Western Siberia. The researchers focused on exploring the polymorphism of the env gene and, in doing so, discovered the new genotypes I_a and I_b, which differ from genotype I. Restrictase Hae III sections the nucleotide sequence of the env gene intofragments with lengths of 316-27-95-5 bp (genotype I), 31-285-27-95-5 bp (genotype I_a), and 31-85-200-27-100 bp (genotype I_b). There are 2.57±0.55% (20 out of 779) samples of genotype I_b which does not differ significantly from 1% (χ²=2.46). Other genotypes were observed in the cattle of Siberia as wild type genotypes (their frequency varied from 17.84 to 32.73 %). This paper explores the effect of the env gene of the cattle leukemia virus on hematological parameters of infected animals. The maximum viral load was observed in animals with the II and IV viral genotypes (1000 – 1400 viral particles per 1000 healthy cells), and the minimum viral load was observed animals with genotype I_b (from 700 to 900 viral particles per 1000 healthy cells). Several hypotheses on the origin of the different genotypes in Siberia are discussed. The probability of the direct introduction of genotype II from South America to Siberia is extremely small and it is more likely that the strain originated independently in an autonomous population with its distribution also occurring independently. A new variety of genotype I (I_b) was found, which can be both a neoplasm and a relict strain.