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 distribution of MD virus (MDV) among T cell subsets from chickens vaccinated or non-vaccinated with MD vaccine and subsequently challenged with a virulent MDV. The challenged MDV was reisolated preferentially from CD4+ T cells, and the average titers of challenged MDV rescued were significantly lower in vaccinated chickens compared to that of non-vaccinated chickens. In addition, it was also shown that different serotypes of MDV, CVI988 and SB-1, have 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 virulent MDV to splenocytes.