Submitted to: American Association of Swine Practitioners Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 10, 1998
Publication Date: N/A
Technical Abstract: Porcine Reproductive and Respiratory Syndrome (PRRS) was first observed about 10 years ago. The viral etiology, PRRS virus (PRRSV), was discovered in 1991 which paved the way for a rapid and extensive flood of data describing almost every aspect of the disease and the biology of the virus. Despite all of this information, many questions still exist about the interactions of the virus with its host, especially when protective immunity and the efficacy of vaccines are discussed. A basic understanding of the swine immune response is necessary to fully understand and evaluate protective immunity and efficacy of vaccines. The preliminary studies reported here attempt to evaluate the humoral immune response in swine to inactivated and attenuated-live virus vaccines using (IFA) and ELISA tests. Twenty-four pigs were divided into 3 equal groups; 7 pigs in each group were vaccinated intramuscularly with 2 ml of a commercially prepared inactivated autogenous vaccine, the remaining pig was a contact control. Each group of vaccinated pigs received a second intramuscular vaccination at either 2, 3, or 4 weeks post-first vaccination. Blood was collected at weekly intervals from day 0 until 2 weeks after the last vaccination and sera was tested for PRRSV-specific antibodies. No antibodies were detected in any pig by the IFA test. Twenty gilts were vaccinated intramuscularly with a live vaccine on experiment days 0 and 28. On day 42 all gilts were seropositive by the IFA test; however, 8 gilts had a titer of 1:40 or less with this assay which may explain the seronegative vaccinated animals found in the field since the ELISA test utilizes sera at a 1:40 dilution. The apparent low antibody titers following vaccination will be further examined with the completion and expansion of these studies.