Seven strains of mice as potential models of bovine pasteurellosis following intranasal challenge with a bovine pneumonic strain of Pasteurella multocida A:3; comparisons of disease and pathological outcomes.

The gram-negative bacterium Pasteurella multocida causes pneumonic and systemic pasteurellosis in bovids for which vaccines are either unavailable or inadequate. The work assessed whether an intranasal P. multocida challenge in mice might provide a model of infection for future vaccine development work. Clinical, pathological and biochemical responses were compared in seven strains of mice challenged with a virulent bovine pneumonic isolate of P. multocida A:3. Six mouse strains (Porton, CD-1, BALB/c, VM, C57BL/10 and C57BL/6) developed clinical signs of pneumonic disease and variable pneumonic lesions 41-70 h post-infection. In contrast, mouse strain RIII became septicaemic within 36 h post-infection. Concentrations of plasma acute phase proteins and serum lipopolysaccharide increased in all mice after infection, and the main or interaction effect of mouse strain and infection status was statistically significant (P<0.05). Responses in C57BL/10 mice showed close similarity to bovine pneumonic and in RIII mice to bovine systemic pasteurellosis.