Re-isolation of Marek's disease virus from T cell subsets of vaccinated and non-vaccinated chickens

To know the effect of Marek's disease (MD) vaccines, we analyzed the distri bution of MD virus (MDV) among T cell subsets from chickens vaccinated or n on-vaccinated with MD vaccine and subsequently challenged with a virulent M DV. The challenged MDV was reisolated preferentially from CD4(+) T cells, a nd the average titers of challenged MDV rescued were significantly lower in vaccinated chickens compared to that of non-vaccinated chickens. In additi on, it was also shown that different serotypes of MDV, CVI988 and SB-1, hav e remarkable difference in recovery rates of viruses from CD4(+) and CD8(+) T cells, though both CVI988 and SB-1 can reduce the infection rates of vir ulent MDV to splenocytes.