Kinetic analysis of T cells and antibody production in chickens infected with Marek's disease virus

In chickens inoculated with a Marek's disease (MD) vaccine and subsequently with virulent MD virus (MDV), CD4+ T cell population was drastically decreased following a transient increase at 21 days after hatching (16 days after MDV infection). To elucidate the immune response after the decrease of CD4+ T cell population, the antibody production against sheep red blood cells (SRBC) was examined in these chickens. Chickens challenged with a virulent MDV after MD vaccination produced lower titers, of anti-SRBC antibody than untreated control chickens. Antibody production against SRBC was also lowered in vaccinated chickens or chickens challenged with a virulent MDV.