Use of Inactivated Corynebacterium pseudotuberculosis as an Immunostimulant with Pneumobac Vaccine

Sheep breeders in Egypt suffer from pneumonic pasteurellosis caused by Pasteurella trehalosi, Pasteurella multocida, and Mannheimia haemolytica. The disease is responsible for significant economic losses in the sheep industry according to the high mortality rate and reduced carcass values. Pneumobac® is the primary vaccine in Egypt used to control pasteurellosis in sheep. Therefore, the aim of the present study was to estimate the nonspecific immune stimulating impact of Corynebacterium pseudotuberculosis ovis against Pasteurella in sheep vaccinated with Pneumobac®. Nine sheep were classified into three groups, each with three animals. The sheep in the first and second groups were inoculated with the inactivated culture of Pneumobac® and a combined inactivated culture of Pneumobac® with Corynebacterium pseudotuberculosis ovis bacterin, respectively. The third group was nonvaccinated and kept in control. Indirect haemagglutination test (IHA) and enzyme-linked immunosorbent assay (ELISA) were used to measure the humoral immune response to the produced vaccines. The results of the present study confirmed that the antibodies titer against Pasteurella multocida type A, D, and B6, Pasteurella trehalosi type T, and Mannheimia haemolytica type A significantly increased in sheep vaccinated with a combined vaccine (Pneumobac® and Corynebacterium pseudotuberculosis ovis bacterin), compared to those vaccinated with Pneumobac® alone. It was concluded that the addition of Corynebacterium pseudotuberculosis ovis bacterin to inactivated Pneumobac® vaccine could increase the immune response against pneumonic pasteurellosis.