Polymorphism of alpha-lactalbumin gene and expression of the p24 protein in the B and T lymphocyte subpopulations in cows naturally infected with bovine leukaemia virus

The aim of the study was to determine the relationship between the polymorphism of the ALA gene and the size of lymphocyte subpopulation expression of viral protein in cows naturally infected with bovine leukaemia virus. The studies were performed on a population of 97 Black-and-White breed cows, aged 3-8 years, from three large herds. The cows were examined three times in monthly intervals beginning from the second half of the first month after calving. Enzootic bovine leukosis diagnosis was based on the identification of p24 viral protein in the lymphocytes of the examined animals and on the white blood cell counts. The fluorescent antibody technique was used to detect p24 protein in the B (B-B2) and T CD4+ and CD8+ lymphocytes. The ALA gene polymorphism at the - 1689 position was assayed with the PCR-RFLP/Sdu I method. It was found that the ALA gene polymorphism differentiated the size of subpopulations of B-B2 lymphocytes and the T CD4+ lymphocytes expressing the p24 protein. This protein was more frequently registered in the B-B2 lymphocytes and in the T CD4+ and CD8 lymphocytes in cows with persistent lymphocytosis than in cows with the aleukaemic form.