The objective of this study was to evaluate the efficacy of three commercial vaccines against experimental pneumonic pasteurellosis in cattle. The three vaccines were: (a) One Shot (SmithKline Beecham, West Chester, PA.), (b) Presponse (Langford Laboratories, Guelph, Ontario) and (c) Once PMH (BioCor, Omaha, NE.). Protective immunity was evaluated in terms of lower clinical and pneumonic lesion scores after endobronchial challenge with virulent P. haemolytica. The results indicate that One Shot elicited antibodies against leukotoxin (Lkt), capsular polysaccharide (CP) and surface antigens (SA), while Presponse and Once PMH elicited antibodies against CP and SA. There was significant correlation between lung and serum antibody levels against Lkt (P < 0.0001), CP (P ≤ 0.0001) and IROMPs (P ≤ 0.035). Animals that received the One Shot had significantly (P ≤ 0.05) lower mean pneumonic lesion score (36.6 ± 10.97) as compared to the control group (48.6 ± 25.92). A significant negative correlation (-0.41; P ≤ 0.008) existed between serum antibody levels against Lkt and pneumonic lesion score. High serum antibodies against SA did not correlate with reduction in pneumonic lesion score. In addition, high antibody levels against CP did not correlate consistently with reduced pneumonic lesion scores. The results from this study demonstrate that commercial vaccines evaluated in this trial did not confer optimal protection in vaccinated calves, against experimental pneumonic pasteurellosis. However, One Shot vaccinates showed a better protective immunity compared to the other two vaccine groups.
Bibliographical noteFunding Information:
This work was supportedb y USDA-Integrated Pest Management competitive grant 92-34103-7155a nd Minnesota Agricultural Experiment Station grant (awardedt o S.K.M and T.R.A).
- commercial vaccines
- pneumonic pasteurellosis
- protective immunity