POLY(METHACRYLIC ACID) HYDROGELS AS CARRIERS OF BACTERIAL EXOTOXINS IN AN ORAL VACCINE FOR CATTLE

Poly(methacrylic acid) hydrogels were tested as a delivery system for oral vaccines in cattle. Hydrogels were absorbed with a vaccine composed of culture supernatants of Pasteurella haemolytica, the most common cause of bacterial pneumonia in cattle. Hydrogels absorbed with culture supernatants were administered orally to calves. Calves were then challenged by an intrabronchial instillation of virulent P. haemolytica. For each calf survival time was recorded. All surviving calves were euthanatized 3 days after challenge. A post mortem examination was performed and the lungs of each calf were evaluated for the size and severity of pneumonic lesions. Calves vaccinated orally with culture supernatants had less lung affected by pneumonia, less severe pneumonic lesions, and lived longer than non-vaccinated calves. Results indicate that hydrogels can be used to deliver oral vaccines to calves to enhance resistance to pneumonia caused by P. haemolytica.