Identification of the immunodominant regions of P1 protein of two genotypes of Mycoplasma pneumoniae through monoclonal antibodies

Mycoplasma pneumoniae (M. pneumoniae), is a significant human respiratory pathogen causing severe atypical pneumonia. Its pathogenicity critically depends on cell adhesion, primarily mediated by the large adhesin protein P1, which contains multiple immunodominant epitopes. However, a precise mapping of these epitopes, particularly in the context of prevalent genotypes I and II, is essential for advancing diagnostic and therapeutic strategies. This study aimed to address this gap by generating specific monoclonal antibodies (mAbs) and delineating the key immunodominant regions on the P1 protein. Sequence alignment of P1 from genotypes I and II revealed high homology, with bioinformatics predicting dominant epitopes clustered in the C-terminal region. Consequently, the C-terminal fragments of both genotypes were recombinantly expressed in a prokaryotic system and used to immunize BALB/c mice for mAb production. Guided by bioinformatic analysis, nine overlapping peptides spanning this region were synthesized. A systematic ELISA-based screening of five anti-P1 mAbs using these peptides. In summary, this study successfully produced genotype-specific mAbs against the P1 C-terminus and defined immunodominant epitopes. These findings provide crucial insights into the biological importance of the P1 protein in pathogenesis. Furthermore, the identified epitopes and specific mAbs establish a foundation for developing improved immunological detection methods and genotyping diagnostics for M. pneumoniae infections, potentially enhancing clinical management and epidemiological surveillance.