Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 21, 2011
Publication Date: July 19, 2011
Citation: Bearson, B.L., Bearson, S.M. 2011. Serological response of swine to an attenuated Salmonella enterica serovar Typhimurium strain that reduces gastrointestinal colonization, fecal shedding and disease due to virulent Salmonella Typhimurium. 9th International Conference on the Epidemiology and Control of biological, chemical and physical hazards in pigs and pork, June 19-22, 2011, Maastricht, Netherlands. p. 228. Technical Abstract: Swine are often asymptomatic carriers of Salmonella spp. Interventions are needed to limit Salmonella colonization of swine to enhance food safety. An attenuated Salmonella enterica serovar Typhimurium mutant strain (BBS 202) was tested in swine to determine whether vaccination could provide protection against wild-type S. Typhimurium challenge. Two groups of piglets (n=14/group) received an intranasal inoculation of BBS 202 or a PBS placebo at 6-weeks of age with a booster 2-weeks later. At 11-weeks of age, all pigs were challenged with the parental, wild-type S. Typhimurium by intranasal inoculation. Average swine rectal temperature (fever) was significantly decreased in BBS 202-vaccinated pigs at days 1 and 2 post-challenge with virulent S. Typhimurium compared to mock-vaccinated pigs. Fecal shedding of wild-type S. Typhimurium was significantly reduced at 2-days post-challenge in BBS 202-vaccinated pigs compared to mock-vaccinated pigs. Colonization of tissues within the gastrointestinal tract by wild-type S. Typhimurium was reduced in BBS 202-vaccinated pigs; a significant decrease in S. Typhimurium colonization of the ileal Peyer’s patch region and ileocecal lymph nodes at 7-days post-challenge was observed. Serological analysis using the IDEXX HerdChek Swine Salmonella Test Kit indicated that all pigs were negative for antibodies to LPS derived from Salmonella serogroups B, C1, and D prior to challenge with wild-type S. Typhimurium. Thus, although vaccinated pigs had received two doses of BBS 202, antibodies from these pigs were not reactive to the LPS antigen in the ELISA test. However, sera from 85% of vaccinated and 78% of mock-vaccinated pigs were positive in the ELISA assay at day-7 post-challenge with wild-type S. Typhimurium. Therefore, preliminary results indicate that vaccination of swine with BBS 202 confers protection against challenge with virulent S. Typhimurium by reducing disease severity, pathogen fecal shedding, and gastrointestinal colonization but does not interfere with herd level monitoring for Salmonella spp.