Immunity to experimental dermatophilosis in rabbits and cattle following immunisation with a live whole cell vaccine

Abstract

The ability of a live whole cell Dermatophilus congolensis vaccine to protect against experimental Dermatophilus infection in rabbits and cattle was assessed. Rabbits were vaccinated intradermally or subcutaneously 7 days before challenge with the vaccine homologous strain of D. congolensis. Intradermally vaccinated animals were revaccinated and both groups together with a third unvaccinated control group were challenged as before.

The cattle were vaccinated intradermally on two occasions and challenged with the vaccine homologous strain 14 days after each vaccination together with control unvaccinated animals. A third challenge or all cattle using the vaccine homologous and a heterologous strain was carried out to examine cross-immunity between different strains of D. congolensis.

In both rabbits and cattle vaccination led to a significant reduction in lesion severity and duration following experimental infection. A similar reduction was observed following infection alone. This effect was less pronounced following heterologous challenge indicating a lack of cross-immunity between different D. congolensis strains. There was no correlation between levels of serum IgG antibody to D. congolensis and lesion severity.