EVALUATION OF AN ORALLY-ADMINISTERED VACCINE, USING HYDROGELS CONTAINING BACTERIAL EXOTOXINS OF PASTEURELLA-HAEMOLYTICA, IN CATTLE

Poly(methacrylic acid) hydrogels were tested for oral delivery of a va ccine against Pasteurella haemolytica infection in cattle. Culture sup ernatants of P haemolytica, the most common bacterium associated with pneumonia in cattle, were used as the antigens in the vaccine. Hydroge ls containing culture supernatants were administered orally to calves. Calves were then challenge-exposed with virulent P haemolytica. Calve s were euthanatized 3 days after challenge exposure. The lungs of each calf were scored for severity and size of pneumonic lesions. Results indicated that vaccinated calves had smaller, less severe pneumonic le sions and lived longer than nonvaccinated calves. These results indica ted that hydrogels can be used to deliver vaccines orally to calves to enhance resistance to pneumonia caused by P haemolytica.