Studies on pasteurellosis. V. Two immunogenic types of Pasteurella multocida associated with fowl cholera
Avian Dis 6(3): 315-321
Two strains of P. multocida isolated from birds with fowl cholera were different immunological types. A vaccine prepared with one type did not stimulate immunity against the other. A bivalent emulsified killed vaccine of these 2 types stimulated and maintained a high level of immunity for 37 weeks (duration of test) against both types. A bivalent aluminum-hydroxide-adsorbed vaccine, however, did not maintain a high level of immunity. Serological tests showed that the 2 strains were different serotypes (Little and Lyons' classification). Serotype 1 fermented dulcitol but not xylose, and was virulent for 16-and 45-week-old chickens. Serotype 3 fermented xylose but not dulcitol, and was virulent for 16-week-old turkeys and 45-week-old chickens; 16-week-old chickens, however, were more resistant to this type.