Formulation of an effective Pasteurella multocida vaccine for sheep.

An effective vaccine for the immunization of sheep against Pasteurella multocida infection was prepared from P. multocida Strain D4 (Type D) and a selected strain of P. multocida Type A. Provided an adequate concentration of bacteria was used, the vaccine thus formulated induced antibodies in sheep that protected mice not only against the vaccine strains but also against infection by a number of heterologous Type A and Type D strains as well as untypable strains. A locally prepared A1(OH)3 gel was found to be an effective adjuvant.