Immune response of chicks inoculated with chicken anemia agent alone or in combination with Marek's disease virus or turkey herpesvirus.

In order to elucidate the depressive effect of chicken anemia agent (CAA) infection on vaccinal immunity of turkey herpesvirus (HVT), cell-mediated and humoral immune responses were studied in chicks inoculated either with chick-passaged CAA alone or with CAA and Marek's disease virus (MDV) or HVT. The response to phytohemagglutinin (PHA) stimulation of splenic lymphocytes from chicks inoculated with chick-passaged CAA at one or seven days of age was significantly depressed on day 12 to 13 postinoculation (PI), but not on day 19 PI. Chicks inoculated with CAA at 14 days of age showed no significantly greater response to PHA. The response was more markedly depressed in chicks dually inoculated with CAA and MDV or HVT than in chicks receiving CAA alone. Serum immunoglobulin levels were apparently normal or relatively low in chicks inoculated with MDV alone or in combination with CAA at one day of age. In contrast, chicks inoculated with HVT at one day of age and/or CAA at one or seven days of age as well as chicks inoculated with MDV at one day of age followed seven days later by CAA inoculation exhibited elevated serum immunoglobulin levels. The production of antibody against HVT was temporarily depressed by CAA infection.