Passive cross-protection provided by antisera directed against in-vivo-expressed antigens of Pasteurella multocida.

Chicken antisera produced against the detergent-insoluble fraction of in vivo-grown P-1059 (serotype 3) Pasteurella multocida passively protected against heterologous X-73 (serotype 1) challenge. Likewise, antisera from chickens that survived infection by live P-1059 provided passive heterologous protection. The two antisera, which contained cross-protection antibodies, were adsorbed with the detergent-insoluble fraction of in vitro-grown P-1059 and still passively cross-protected against heterologous serotype challenge. The proteins of in vivo-grown P-1059 that had molecular weights of 204,000, 192,000, 179,000, and 153,000, which were recognized by the adsorbed antisera on immunoblots, may be responsible for cross-protection.