Depression of vaccinal immunity to Marek's disease by infection with chicken anaemia agent.
Chicken anaemia agent (CAA) depressed protective vaccinal immunity against Marek's disease (MD) when vaccinated chicks were inoculated with CAA at 1 to 14 days of age. In chicks inoculated with CAA alone, a typical CAA infection as manifested by early mortality, decrease in haematocrit value, severe lymphoid depletion in the lymphoid organs, and aplasia of the bone marrow occurred only when one-day-old chicks were inoculated. When both turkey herpesvirus (HVT) and CAA were inoculated, a typical CAA infection occurred even if chicks were inoculated with CAA at 8 days of age. The response of splenic lymphocytes to mitogen stimulation was more severely depressed in chicks dually inoculated with HVT and CAA than in chicks inoculated with CAA alone. These results suggest that the depressive effect of CAA infection on HVT vaccinal immunity may be due to a severe impairment to T cell-mediated immunity resulting from enhanced pathogenicity of CAA in vaccinated chicks.
Otaaki
Y
Y
Nippon Institute for Biological Science, Tokyo, Japan.
Nunoya
T
T
Tajima
M
M
Kato
A
A
Nomura
Y
Y