Detection of specific antibodies of classes G and M to bovine leukemia virus in the blood serum

[Characterization of B1-cells during experimental leukomogenesis.]

BACKGROUND

Bovine leukemia causes a significant polyclonal expansion of CD5+, IgM+ B lymphocytes, known as persistent lymphocytosis (PL), in approximately 30% of infected cattle. However, it is not yet clear what happens to this subpopulation of B cells in the early period of infection of animals.

PURPOSE

Quantitative characterization of IgM+ and CD5+ B cells during the immune response, which can provide important information on the mechanisms of lymphocyte priming in BLV infection.

MATERIAL AND METHODS

The experiment used BLV-negative calves of black-motley breed at the age of 8 months (n = 11). Animals (n = 8) were intravenously injected with blood of a BLV-positive cow. Control calves (n = 3) were injected with saline. Studies were performed before and after infection on days 5, 7, 14, 21, 28 and 65 of the immune response. The determination of the number of B-lymphocytes in the blood was carried out by the method of immunoperoxidase staining based on monoclonal antibodies to IgM, CD5.

RESULTS

As a result of the studies, it was found that the level of CD5+ B cells increases on the 14th day of the primary immune response, characterized by polyclonal proliferation of CD5+ B cells, which are the primary target for BLV. Our research data confirm that in the lymphocytes of experimentally infected cattle, surface aggregation of IgM and CD5 molecules on B-lymphocytes is absent.

DISCUSSION

It is known that the wave-like nature of IgM synthesis, which was shown in previous studies, depends on a subpopulation of B1 cells. After 7 days of the immune response, IgM+ and CD5+ cells do not correlate, which shows their functional difference. The increase in CD5+ cells is probably not associated with B cells, but with T cells differentiating under the influence of the virus.

CONCLUSIONS

A subset of B1 cells is the primary target of cattle leukemia virus. The 65th day of the immune response is characterized by the expansion of IgM+ B cells, a decrease in the number of CD5+ cells and a uniform distribution of receptors around the perimeter of the cells.

Development of approaches to the diagnosis of cattle leukemia in the system of antiepizootic measures in the Belgorod Region

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.