Immunogenicity Evaluation of Six Key Antigens of Mycoplasma pneumoniae in BALB/c Mice

Background/Objective:Mycoplasma pneumoniae (MP) remains a significant pathogen causing respiratory tract inflammation, particularly in the elderly and children under 5 years old. The lack of an effective vaccine is primarily attributed to the absence of well-defined immunological targets. This study systematically evaluated the immunological characteristics of six key MP proteins to facilitate vaccine development. Methods: We constructed recombinant plasmids (pET30a-CARDS/P1/P40-90/P30/P116/MPN133), expressed them in Escherichia coli, and evaluated their immunogenicity and immune reactivity against MP infection in BALB/c mice. Results: Six proteins induced strong antibody responses. Sera from all protein-immunized groups exhibited MP growth inhibitory activity, with P116 and MPN133 showing more pronounced inhibitory effects. After MP challenge, lung histopathological findings demonstrated that, except for the P1 group, the lung pathological scores of the protein-immunized groups were lower than those of the PBS control group, and the lung injury in the CARDS, P116 and MPN133 groups was significantly alleviated. Conclusions: The six recombinant proteins demonstrate good immunogenicity. Among them, CARDS induces a strong primary antibody response, while P116 and MPN133 elicit potent anti-MP antibodies. In addition, CARDS, P116 and MPN133 significantly alleviate lung pathological damage (n = 6, p < 0.01), indicating that these three proteins have greater potential as MP vaccine targets among the six candidate proteins.