Summary: This experiment was conducted to evaluate the cellular and mucosal responses in the respiratory tract of Nigerian goats vaccinated intranasally with recombinant
Mannheimia hemolytica
bacterine. Twenty one goats were divided into five groups, five goats each in three vaccinated groups while three goats each in two other groups serve as positive and negative control. Group A was vaccinated once; group B was vaccinated twice at one week interval, and group D at twice at two weeks interval. Group C1 were the unvaccinated and challenged, while group C2 were unvaccinated and unchallenged. The bronchoalveolar lavage differential counts and bronchial associated lymphoid tissue (BALT) responses were measured using Giemsa stained thin smear of the cell fraction of the lavage and histomorphometry. ANOVA were employed and significance was at p>0.05. The post-challenge macrophage to neutrophil (M:N) ratio values of group B goats was the highest and the ratio differed from other groups which had much lower M:N values. The exposure in group B resulted in significant increase in number and size of BALTs as well as the number of lymphocytes in BALT than those of the other groups. This study showed that intranasal vaccination of the recombinant
Mannheimia hemolytica bacterine twice at a week interval was more efficient in inducing strong mucosal and defensive cellular responses in the respiratory tract.
