Detection of Salmonella-specific antibody in swine oral fluids

Authors: Atkinson, Briony; Bearson, Bradley - Brad; Loving, Crystal; ZIMMERMAN, JEFFREY - Iowa State University; KICH, JALUSA - Embrapa-Pigs And Poultry; Bearson, Shawn

Submitted to: BMC Porcine Health Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2019
Publication Date: 12/16/2019
Citation: Atkinson, B.M., Bearson, B.L., Loving, C.L., Zimmerman, J.J., Kich, J.D., Bearson, S.M. 2019. Detection of Salmonella-specific antibody in swine oral fluids. BMC Porcine Health Management. 5(29). https://doi.org/10.1186/s40813-019-0136-7.
DOI: https://doi.org/10.1186/s40813-019-0136-7

Interpretive Summary: Salmonella is a common source of bacterial foodborne-related illness, and between 1998-2016, pork products were the third highest associated food source. Because pigs are often colonized with Salmonella without showing clinical signs (i.e. carriers), the swine industry would benefit from an assay that detects Salmonella exposure and herd level immunity. The immune system of an animal makes antibodies to bacteria during an infection. A study was performed that evaluated the oral fluids (saliva) of pigs for antibodies against Salmonella. Oral fluids were collected from cotton ropes chewed on by a group of Salmonella-positive pigs. Using a laboratory assay to detect antibodies, the oral fluid samples tested positive for Salmonella antibodies. The results suggest that oral fluids could serve as a non-invasive sample source to detect anti-Salmonella antibody, thereby functioning as a valuable surveillance tool for herd level monitoring of Salmonella exposure.

Technical Abstract: Salmonella is a leading cause of bacterial foodborne-related illness, and over the last two decades, pork products were the third highest food-associated source. With greater than 50 percent of U.S. swine herds testing positive for Salmonella, carrier pigs that shed Salmonella in their feces without showing clinical signs are a food safety and environmental contamination issue. Herd level surveillance of Salmonella shedding status is useful, but collection of feces and culture methods for Salmonella detection are laborious and time-consuming. Surveillance for Salmonella-exposure through detection of Salmonella-specific serum antibody is a reliable method, but presents labor and animal-welfare issues. Oral fluids are a reliable, antemortem sample with proven utility for surveillance in the swine industry. In the current study, we tested oral fluid samples as a potential non-invasive, repeatable sample type for Salmonella-specific antibodies. A laboratory-developed, indirect enzyme-linked immunosorbent assay (ELISA) detected anti-Salmonella IgG, IgM, and predominantly IgA in oral fluids from Salmonella enterica serovar Typhimurium-exposed pigs. Furthermore, with minor modifications, a commercial ELISA-based kit also detected Salmonella-specific antibodies in oral fluids. Collectively, oral fluids may serve as a prospective surveillance tool for herd level monitoring of Salmonella exposure.