EN
The aim of the study was the comparison of the percentage of the T lymphocytes subpopulation in the blood of chickens vaccinated against Marek’s disease in ovo or during the first day of life. The commercial, lyophylised turkey vaccine strain HVT FC 126 was used in the experiment. A dose of 2400 PFU of the vaccine virus was applied to 28 chicken SPF embryos (group I) on the 18th day of incubation. Group II was constituted by 23 one-day-old chicks, inoculated with the mentioned dose of the virus, three hours after breeding. The control group was represented by twenty-two non vaccinated birds. All the groups were kept in separate rooms. Blood samples were collected on 1st , 3rd, 7th, 10th, 14th, 28th, 42th and 56th days of life. FICT labeled monoclonal mouse antibodies against chicken surface receptors CD3+, CD4+, and CD8+ were applied for determining T lymphocyte subpopulations. A flow cytometer was used for the designation of markers on the cell surface. In the first week of life, a higher percentage of T lymphocytes CD3+, CD4+, and CD8+ was observed in vaccinated birds (group I and II) in comparison to the control group. However, the observed differences were not statistically significant. Later on the examined parameters were similar to the physiological ones, but differentiation between particular groups was noticed. The vaccination with HVT FC 126 strain in ovo or in the first day of life did not result in quantitative changes in T lymphocyte subpopulations in peripheral blood.