Homologous Bacterial DNA as an Adjuvant for the development of humoral and cellular immune responses against Pasteurella multocida in sheep

Pasteurella (P.) maltocida is the cause of pasteurellosis. Animals and sometimes humans are involved with this bacterium. The aim of this study was to evaluate immune responses in sheep vaccinated with inactive antigen along with alum and AbDNA adjuvant by tracking IgG and cytokine levels on serum samples.

Sheep were immunized with two doses of inactivated vaccine with formalin at an interval of 2 weeks. Alum and DNA of P.maltocida serotype A strain were used as an adjuvant. One milliliter of immunogen was inoculated subcutaneously to the animals. After  ELISA design, immune response was evaluated by measuring specific IgG antibody titer and TNF-α measurement on serum samples and lymphocyte cell culture.

The antibody titer in the group receiving DNA was higher than the group receiving Alum and the control groups. The highest antibody level (1.463) was related to the FIV-AbDNA group in the fourth week. In the FIV-Alum group, the highest titer was 1.054, which indicates a weaker immune response compared to the DNA group. AbDNA also increased the production of TNF-α. TNF-α in immunized animals increased significantly compared to the control groups. The highest titer of TNF-α (1.44) was related to the FIV-AbDNA group on the serum sample.

P.maltocida antigen together with bacterial DNA as an adjuvant is an alternative candidate for making new vaccines against P.maltocida. Considering the ability of AbDNA to   create immune responses through the release of different cytokines, it is suggested to evaluate different types of cytokines.