Colostral immunity in piglets from sows vaccinated with inactivated Aujeszky disease virus vaccine.

Neutralizing antibodies against ADV were transmitted from sows, vaccinated with inactivated ADV adjuvanted with DEAE dextran, to their offspring via colostrum. The suckling piglets were protected by colostral immunity against contact infection with ADV at week 1 p.p., however, they were not protected against i.n. infection (10(8) TCD50). At 2 and 3 weeks p.p. all the piglets were protected against both contact infection and i.n. infection. At 4 weeks p.p. 50 per cent of the litter were protected against i.n. infection, in spite of very low antibody titres (1:2--1:4). The colostral antibodies did not interfere with active antibody response when the piglets were vaccinated with the inactivated vaccine from 2 weeks p.p. onward. Lymphocytes from suckling piglets of a vaccinated sow showed in vitro reactivity (enhanced 3H-thymidine incorporation) against ADV and BHK antigen, both contained in the vaccine used for the immunization of the sow.