Immune response of sows vaccinated with attenuated transmissible gastroenteritis virus (TGEV) and recombinant TGEV spike protein vaccines and protection of their suckling pigs against virulent TGEV challenge exposure
Park, S.; Sestak, K.; Hodgins, D.C.; Shoup, D.I.; Ward, L.A.; Jackwood, D.J.; Saif, L.J.
American Journal of Veterinary Research 59(8): 1002-1008
1998
ISSN/ISBN: 0002-9645 PMID: 9706204 Document Number: 492052
TGEV-seronegative sows and their pigs were used in an investigation comparing recombinant TGEV spike protein (SP), R2-2, with attenuated live virus (ALV) vaccine in sows during late pregnancy. At prepartum weeks (PPW) 6 and 4, sows of groups 1 (3 sows, 28 pigs) and 2 (3 sows, 25 pigs) received ALV via the oral/intranasal (o.r./i.n.) route. At PPW 2, group-1 sows received ALV i.m. and group-2 sows received SPR2-2 i.m. Group-3 (3 sows, 21 pigs) sows received SPR2-2 i.m. at PPW 4 and ALV o.r./i.n. at PPW 2. Sows of group 4 (negative controls, 4 sows, 32 pigs) were inoculated o.r./i.n. with mock-infected ST cell fluids at PPW 6 and 4 and i.m. with Sf9 cell lysates at PPW2 (2 sows), or i.m. with Sf9 cell lysates at PPW4 and o.r./i.n. with mock-infected ST cell fluids at PPW2 (2 sows). Serum, colostrum and milk samples were tested for antibody to TGEV, and a lymphoproliferative (LP) assay was performed on blood mononuclear cells. Suckling pigs were challenge-exposed with virulent TGEV. Sows of groups 1 and 2 had higher IgG and significantly higher antibody titres in colostrum. Their pigs had significantly higher serum antibody titre. At challenge exposure of their pigs, LP responses of group-2 sows were significantly higher than those of sows in the other 3 groups. Mean pig mortality ranged from 43 (group 2) to 92% (group 4). There were significant negative correlations between litter mortality and sow LP response, colostral titre and pig serum titre at time of challenge exposure. In sows vaccinated twice with attenuated live TGEV, the recombinant SPR2-2 administered i.m. may be comparable to ALV administered i.m. as a booster. Vaccination failed to provide complete protection to suckling pigs after challenge exposure.