Lymphocyte responses to African swine fever virus infection.

The immunological response of pigs infected with African swine fever virus was related to both quantitative and qualitative changes in the lymphocyte population. The cytolytic effect of the virus on lymphocytes caused a proportionally greater drop in B cell than in T cell numbers. A blastogenic test was developed to measure the appearance of specifically sensitised lymphocytes in the circulation. These appeared about 10 days after infection in animals infected with attenuated virus; pigs infected with virulent strains died before the appearance of this response.