Effect of vaccination against Salmonella Typhimurium in pigs under field conditions (SUSALVAC)

The general aim of the project is to improve the control of Salmonella infections of pigs to deliver scientifically sound advice about the effect of vaccination against Salmonella under field conditions and its eventual implementation in a national control program. The specific objectives are: 1. To investigate to which extent vaccination of sows and/or piglets can play a role in the control of Salmonella Typhimurium (S. Typhimurium) infection under Belgian pig production conditions. The ultimate goal is to produce slaughter pigs that present only a marginal risk for S. Typhimurium exposure to humans. The experiments are conducted under field conditions on farms with differing Salmonella status and management. 2. To investigate how vaccination can be incorporated in a new Salmonella control program that accounts for the necessity of monitoring the farm contamination status and the Salmonella status of herds of slaughter pigs.

First we investigate several vaccination schemes on a number of closed pig farms with a commercial live attenuated S. Typhimurium vaccine (Salmoporc, IDT Biologika) given to sows and/or piglets. Then we determine the effect of group vaccination of sows on breeding farms. The excretion of Salmonella is investigated through bacteriological analysis of feces of sows and pigs. Carriers are determined by bacteriological analysis of lymph nodes of slaughter pigs or breeding animals. Serological analysis is also performed on different age groups. Later we type the Salmonella strains isolated from animals of different groups and ages. This will give us information of the eventual differential effect of vaccination on different Salmonella types, and it will show to which extent Salmonella strains from different age groups and matrices (feces, lymph nodes) are identical. Typing also allows to investigate the eventual shedding and persistence of the vaccine strain. Finally, the possible implementation of vaccination in a new Salmonella control program will be assessed. For that purpose, the effectiveness of the investigated vaccination schemes, the possible shedding of the vaccine strain and the effect of vaccination on the monitoring of the Salmonella contamination (serological, bacteriological) of farms and herds of slaughter pigs will be taken into account.

This project allows government authorities to assess the validity of vaccination in a national Salmonella control program for the pig sector. If the vaccination program were to be applied,  this project reveals how the contamination status of vaccinated farms can best be monitored. The type of studies performed and the use of the only available commercial vaccine ensure that the results are specific and concrete, ideal for the governmental authorities. The project also feeds possible future studies on immune response, the effect on zootechnical parameters, different application modes, etc. Such research could lead to better vaccines. We plan to publish the results in scientific journals and to present them at national and international scientific symposia and congresses.

External partner(s)
CODA-CERVA - Centrum Onderzoek Diergeneeskunde & Agrochemie
DGZ - Dierengezondheidszorg Vlaanderen
UGent
Ugent - Fac. Diergeneeskunde