Molecular typing of BLV samples isolated from Holsteinized Russian Black Pied cattle was carried out, and various cytofluorometric and morphological blood indices were examined. We performed the total count of white blood cells (WBC), lymphocyte (lymf), granulocyte (gran), monocyte (mon), red blood cell (RBC), hemoglobin (HGB), hematocrit (HTC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), red blood cell distribution width (RDW), platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW), and platelet crit count (PCT). The LTR-region of BLV was haplotyped. Only viruses of haplotypes I (0.33±0.03) and III (0.67±0.03) of the eight possible were detected. The ratio of hematologically sick, healthy, and suspected carriers of BLV of haplotypes I and II was comparable with the results of other researchers. The numbers of leukocytes, erythrocytes and platelets in the blood of carriers of haplotype III exceeded the corresponding parameters of cattle affected by the virus of haplotype I. It is interesting to note that the difference in the hemolytic status of animals was manifested not only by the concentration of leukocytes as direct immune agents but also by the count of erythrocytes and platelets, which are not directly involved in the immune response. The number of particles of haplotype III of the BLV circulating in the blood of infected individuals exceeded that of the carriers of haplotype I. In this connection, an assumption was made about the evolutionary advantage of the more virulent haplotype III. However, the results of our own research in conjunction with the data of other scientists indicate that the high virulence of individual virus strains is a consequence of the tendency to implement the maximum possible intensity of the synthesis of virus particles but not of the high damaging effect alone. It is shown that high lethality is evolutionarily disadvantageous for viruses, since the extinction of the carrier as a biological species is fraught with the disappearance of the virus itself.

Background This study describes the biodiversity and properties of Bovine leukemia virus in Western Siberia. This paper explores the effect of different genotypes of the env gene of the cattle leukemia virus on hematological parameters of infected animals. The researchers focused on exploring the polymorphism of the env gene and, in doing so, discovered the new genotypes Ia and Ib, which differ from genotype I. Several hypotheses on the origin of the different genotypes in Siberia are discussed. Results We obtained varying length of the restriction fragments for genotypes I. Additionally using restrictase Hae III were received fragments was named genotype Ia, and genotype Ib. There are 2.57 ± 0.55% (20 out of 779) samples of genotype Ib 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%). 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 Ib (from 700 to 900 viral particles per 1000 healthy cells). Conclusions 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 (Ib) was found, which can be both a neoplasm and a relict strain.

The purpose of the study was the search for microorganisms capable of suppressing quorum feelings associated with the production of phenazines (pyocyanin). The formation of pyocyanine, related to oxyphenazines, is one of the indicators of the quorum-sensing reaction. In order to search for antagonistically active bacterial strains, the microorganisms were co-cullured with the cultures of Pseudomonas aeruginosa wherein the suppression of oxyphenazine production was determined. We used 14 cultures of bacteria from the genera Pseudomonas, Acinetobacter, Enterobacter, Staphylococcus, Microbacterium, Serratia, Sphingobacterium, Lactobacillus, Weisella to find strains suppressing the production of pyocyanin. Piocanin was successively extracted with chloroform and 0.2 M hydrochloric acid, after which its content was determined spectrophotometrically at a wavelength of 520 nm. Several bacterial cultures characterized by the ability to inhibit the production of oxyphenazine in co-cultivation tests with Pseudomonas aeruginosa were found. The identified microorganisms belonged to the microorganisms of the genera Acinetobacter and Pseudomonas, Lactobacillus and Weisella. The Kruskal-Wallis criterion - H (5, N = 21) = 11.86902 is statistically significant (p = 0.0366). The distribution of cultures in the inhibition of the production of oxyphenazines in the experiments on co-cultivation with Pseudomonas aeruginosa was not binomial, which implies the non-random nature of the distribution of cultures according to the results of co-cultivation. Thus, the levels of inhibition of the production of phenazines for different taxa of bacteria in the co-cultivation tests were statistically significantly different from each other. The largest sum of ranks belongs to the group Lactobacillus spp. and this taxon has the greatest effect on the content of phenazines. The decrease in the concentration of fhe final product (pyocyanin), the synthesis of which is initiated by butanol-homoserine lactone, can be associated with the mechanisms of quorum-quenching, and the mechanisms of antagonistic activity of microorganisms that affect the production of the aforementioned metabolites of P. aeruginosa.

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The analysis of the epizootic situation of cattle leukemia in the Siberian Federal District as a whole and in individual regions of the district is given. The study was carried out in the Republics of Altai, Tuva and Khakassia, in the Altai and Krasnoyarsk Territories and in five regions: Irkutsk, Kemerovo, Novosibirsk, Omsk and Tomsk. The materials of diagnostic studies obtained by veterinary specialists of the Siberian Federal District for 2017-2019 are presented. This information has been analyzed and summarized both for the Siberian Federal District as a whole and for its individual constituent entities. Studies show the spread of bovine leukemia virus infection in the whole district. A tense epizootic situation with cattle leukemia was noted, since the Siberian Federal District ranks second in Russia in terms of the number of adverse locations (322). However, compared to 2017, the number of adverse locations in 2019 decreased by 57, sick animals - by 977 heads, infected animals - by 70836 heads. The number of adverse locations has decreased slightly, while the number of infected animals in some regions has increased. As of January 1, 2020, no hematologically sick animals were found in the Republics of Altai, Khakassia, Buryatia and Tuva, but the number of animals infected with BLV increased. The experience of individual regions of the country that are free from BLV infection (Sverdlovsk, Vologda, Leningrad, Murmansk, Arkhangelsk, Kostroma, Kirov regions, Khanty-Mansi Autonomous District, etc.) shows that bovine leukemia is an infection that can be controlled. It is possible to eliminate the disease in herds of cattle with any level of BLV infection as a result of carrying out complex health-improving measures, as well as organizational and veterinary-sanitary measures with the obligatory removal of sick and BLV infected animals from the herd.