Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2016
Publication Date: 4/4/2016
Publication URL: https://handle.nal.usda.gov/10113/5319117
Citation: Bearson, B.L., Bearson, S.M., Kich, J.D. 2016. A DIVA vaccine for cross-protection against Salmonella. Vaccine. 34:1241-1246. https://doi.org/10.1016/j.vaccine.2016.01.036.
Interpretive Summary: Salmonella is a leading cause of bacterial foodborne disease in humans. Pigs are often colonized with Salmonella in their gastrointestinal tract, which can negatively influence animal health and result in pork contamination during slaughter. Vaccination of pigs against Salmonella may effectively reduce colonization and disease due to the bacterial pathogen. However, current Salmonella vaccines provide limited protection against the large variety of Salmonella strains that exist. Furthermore, Salmonella vaccines can interfere with current surveillance programs that monitor the presence of Salmonella in swine herds. We developed and tested a Salmonella vaccine to protect against multiple Salmonella strains without interfering with Salmonella monitoring programs. The developed Salmonella vaccine is anticipated to protect animal health while enhancing food safety.
Technical Abstract: Swine are often asymptomatic carriers of Salmonella spp., a leading cause of human bacterial foodborne disease. Vaccination against Salmonella is effective for protection of animal health and enhancement of food safety. However, current vaccines for swine may only offer limited cross-protection against heterologous serovars as well as interfere with surveillance programs that monitor the Salmonella status of swine herds. To overcome Salmonella vaccine limitations, we rationally designed and constructed an attenuated Salmonella enterica serovar Typhimurium vaccine (BBS 866) by deletion of multiple small RNA (sRNA) genes (omrA, omrB, rybB, micA, and invR) in combination with an rfaH mutation. We vaccinated swine intranasally at 3-weeks of age with PBS (mock-vaccinated), BBS 866 or BBS 202 (S. Typhimurium rfaH, Bearson et al. 2014) and challenged at 7-weeks of age with virulent S. Choleraesuis. Vaccination with BBS 866 enhanced protection against S. Choleraesuis by significantly limiting the duration of fever, the levels of circulating INF', and the total number of swine with S. Choleraesuis septicemia. Vaccination with either BBS 866 or BBS 202 significantly reduced recovery of S. Choleraesuis from both systemic (spleen and liver) and gastrointestinal (Peyer’s Patch, Ileocecal lymph nodes, and cecum) tissues. Similar to our earlier report for BBS 202, the BBS 866 vaccine strain can be used in swine without compromising the differentiation of infected from vaccinated animals (DIVA). Therefore, the attenuated S. Typhimurium BBS 866 strain, containing mutations in rfaH and multiple sRNAs, addresses the limitations of current Salmonella vaccines by providing cross-protection against S. Choleraesuis in swine without interfering with established monitoring programs for Salmonella surveillance.