IMMUNIZATION OF PREGNANT GILTS WITH PRCV INDUCES LACTOGENIC IMMUNITY FOR PROTECTION OF NURSING PIGLETS FROM CHALLENGE WITH TGEV

The level of passive protection against transmissible gastroenteritis virus (TGEV) was evaluated by experimentally infecting 12 pregnant gil ts with different doses of porcine respiratory coronavirus (PRCV) and challenging their litters at 4 days of age. An overall survival rate o f 70% was found for piglets nursing the 12 PRCV-infected gilts, compar ed to a 16% survival rate for piglets of nine uninfected control gilts . Six of the PRCV-infected gilts had adequate levels of immunity to re sist infection with TGEV following the challenge of their litters. The se six completely immuned gilts also solidly protected their litters f rom TGEV as shown by a 96% piglet survival rate through weaning at 3 w eeks of age. The results suggest that respiratory infection with PRCV induces a substantial degree of protective lactogenic immunity against TGEV.