Abstract
Pasteurella multocida (Pm) is a major zoonotic pathogen that causes avian cholera in poultry, leading to significant economic losses. Although inactivated vaccines are commonly used, their immunogenicity is limited, highlighting the need for safer and more effective vaccine strategies. PlpE is a conserved antigen of Pm, making it a promising candidate for the development of subunit vaccines. This study aimed to evaluate the immuno-enhancing effect of a PlpE multi-epitope protein incorporated into an aluminum hydroxide-adjuvanted inactivated vaccine against local Pm strain infection. Antigenic epitopes of PlpE were identified through bioinformatics analysis, and regions rich in antigenic epitopes were selected for protein expression and purification. Concurrently, an aluminum hydroxide-adjuvanted inactivated vaccine was prepared, and the purified PlpE multi-epitope protein was incorporated into the vaccine formulation. The immunoprotective effects of these vaccines were tested in chicken models. The results showed that the survival rate was 80 % in the PlpE multi-epitope protein combined with the aluminum hydroxide-adjuvanted inactivated vaccine group, which was higher than the rate of the aluminum hydroxide-adjuvanted inactivated vaccine group (70 %) and the PlpE multi-epitope protein vaccine group (50 %). The degree of pathological changes was significantly reduced and the IgG levels were significant elevated in the PlpE multi-epitope protein combined with the aluminum hydroxide-adjuvanted inactivated vaccine group compared with the aluminum hydroxide-adjuvanted inactivated vaccine group and the PlpE multi-epitope protein vaccine group. In conclusion, incorporating the PlpE multi-epitope protein into the aluminum hydroxide-adjuvanted inactivated vaccine significantly enhances its immunoprotective efficacy against Pm infection in chickens.