Immunisation of chickens against Campylobacter infections (CAMPIMMUN)

Contaminated poultry meat is the most important source for Campylobacter jejuni infections in humans, the cost of which is estimated at  almost 11 billion euro per year in Belgium. At present there are yet no efficient control measures to reduce the Campylobacter prevalence of broilers during primary production. In previous research, we have demonstrated that oral passive immunization with antibodies from eggs against C. jejuni can reduce the Campylobacter load in the cecum drastically. This project aims to investigate whether this strategy in order to combat C. jejuni and C. coli infections of chickens is practable under field conditions. Furthermore, we investigate to what extent active immunization of chickens can protect against colonization with C. jejuni and C. coli.

First, the project coordinator (Ghent University) has composed the vaccines to vaccinate layer hens (production of hyperimmune eggs for passive immunization) and broilers (active immunization). For that purpose, two strategies have been chosen: 1) a bacterin of a mixture of C. jejuni and C. coli strains that are as diverse as possible (obtained from ILVO) and 2) a subunit vaccine consisting of a mixture of immunoreactive antigens. In a second step, the layers were vaccinated with the bacterin or with the subunit vaccine. Subsequently, the hyperimmune eggs were used to optimize oral passive immunization of broilers. The extent to which each of the two vaccines is able to protect broilers against Campylobacter infections after in ovo vaccination was examined. Finally, we calculated the cost of possible passive and/or active immunization of broilers.

In-ovo vaccination with the subunit vaccine or the bacterin did not elicit a significant antibody response in broilers and therefore does not protect against Campylobacter colonization. In contrast, oral passive immunization of broilers with hyperimmune egg yolks from subunit or bacterin immunized layers resulted in a significant reduction of the number of Campylobacter bacteria in the ceca of a colonized animal, but only upon supplementation of bacterin egg yolks. A better protection was achieved with a preventive application, where both treatments resulted in significant lowering of the percentage of Campylobacter infected animals. From the cost-benefit analysis, it seems that preventive oral passive immunization is not economically feasible due to the cost of the eggs. According to the researchers, the vaccines could be used in other alternative ways. The results have been presented at an international poultry congress and published in two scientific A1 articles, and will result in a publicly defended PhD thesis at Ghent University.

External partner(s)
UGent