Clostridium perfringens is a bacterial strain that resides in the intestines of chickens. When the
bacterium is able to multiply, it can cause necrotic enteritis within the gut. This disease can cause
severe (damaged gut with lesions or sores leading to death) or mild (small lesions, lower body
weight gain, high feed conversion ratio) symptoms and has a huge economic impact on the poultry
industry. In the past, antibiotics were used as a growth promoter in order to fatten the animals.
Since the ban of these drugs due to the concern of antibiotic resistance, the prevalence of the
disease has risen. Vaccination could be a good alternative. Classic vaccination using a needle
however is not applicable in the field. During this project, an oral vaccine will be developed that
can be added to the feed or water supply of the animals. A modified Bacillus subtilis strain will be
used as a vector to deliver and present an antigen to the immune system of the broiler. These
resistant spores will be administered orally because they are able to survive the harsh conditions
in the gastrointestinal tract. In order to extend the residence time in the gut and eventually
increase the interaction with immune cells, the spores are made sticky. The best sticky molecule as
well as the best antigen and expression site will be chosen in a step-by-step manner. After
developing the optimal modified strain, its protective effect will be assessed in an infection trial.