Adsorption of colostral antibodies against classical swine fever, persistence of maternal antibodies, and effect on response to vaccination in baby pigs

Objective-To determine kinetics of antibody absorption, persistence of anti body concentrations, and influence of titers on vaccination of baby pigs wi th a vaccine against classical swine fever (CSF). Animals-15 sows and their litters. Procedure-Farrowings were supervised. Initial time of suckling was recorded . In the first experiment, blood samples were collected at farrowing, 2 and 4 hours after suckling, and hourly until 10 hours after ink tial suckling. Samples were assayed for CSF antibodies, using a serum neutralizing (SN) t est. A second experiment included 33 baby pigs vaccinated as follows: 10 pr ior to ingestion of colostrum, 18 between 1 and 4 hours after ingestion of colostrum, and 5 at 12 hours after ingestion of colostrum. Fourteen pigs we re vaccinated when 7 weeks old, and 15 pigs were not vaccinated. At 10 week s of age, pigs were challenge-exposed with virulent CSF virus. Blood sample s were collected and assayed for CSF antibodies and p125 antigen and p125 a ntibodies. Results-CSF antibodies were detected in pigs beginning 2 hours after suckli ng, Colostral antibodies persisted for > 7 weeks (half-life, 7.9 days). Vac cination of pigs before suckling provided effective protection from severe disease after challenge-exposure. However vaccination of neonates with anti body titers was not effective, because 19 of 23 (82%) pigs succumbed after challenge-exposure, All pigs vaccinated when 7 weeks old resisted challenge -exposure, whereas all unvaccinated control pigs succumbed. Conclusions and Clinical Relevance Vaccination before ingestion of colostru m conferred good protection against CSF in baby pigs. Vaccination of 7-week -old pigs that had decreasing concentrations of passively acquired antibodi es was efficacious.