Ag85A, As an S2 Vaccine Carrier, Reduces the Toxicity of the S2 Vaccine and Enhances the Protective Ability of Mice against Brucella

Brucella is a globally distributed zoonotic disease that can cause abortion and changes in immune function in humans and animals. At present, there is no good treatment plan for Brucella, and animals can only be treated harmlessly once they become ill, resulting in huge economic losses. Therefore, the prevention of Brucella infection is a very crucial step. Although a variety of Brucella vaccines have been widely used, they have varying degrees of shortcomings. For example, some Brucella vaccines have residual virulence, which leads to the emergence of Brucella in animals during the immunization process. Bacillus infection and other conditions occur. To further reduce the toxicity of the Brucella vaccine and enhance its protective effect on animals, this study used Antigen 85A (Ag85A) as a carrier of the Brucella vaccine to fuse with the Brucella S2 vaccine. The results of the study found that the S2-Ag85A oral Brucella vaccine could effectively reduce the toxicity residue of the S2 vaccine, stimulate the mice to produce a better immunogenic response, and effectively activate the expression levels of Brucella heterozygous IgG1 and IgG2a. Experiments have shown that the expression of IFN-γ in the peripheral blood serum and spleen of mice is significantly increased, and the expression levels of IL-1β, TNF-α, and IL-6 are significantly reduced, which may indicate that S2-Ag85A oral Brucella vaccine could induce the expression of IFN-γ, thus downregulating the expression levels of IL-6 and TNF-α in the spleen tissue. The above results indicate that the S2-Ag85A oral vaccine is an effective attenuated vaccine for preventing Brucella infection.