Identification of mimotope of Mycoplasma pneumoniae P1 protein and its potential value in serodiagnosis

Traditional diagnostic methods cannot meet the requirements for rapid diagnosis of Mycoplasma pneumoniae. Therefore, developing a serological diagnostic method with high specificity and sensitivity is urgent. In this study, we expressed and purified the recombinant P1' protein, which comprises amino-acid residues 1160-1498 of the P1 protein. Thereafter, after immunising New Zealand rabbits, we purified the anti-P1' polyclonal antibody using cyanogen bromide-activated sepharose 4B. By using this purified antibody as target molecule, we then performed a 4-round biopanning for a phage display random 12-mer peptide library. After sequencing analysis, we found that the polypeptide HLQMRLTKLRMP was a 12-mer peptide specifically binding to the anti-P1' polyclonal antibody and had 75% homology with the 1266-1272 amino acid (QVRTKLR) of the M. pneumoniae P1 protein. Besides, we further confirmed that the representative phage 1 which displayed this peptide could specifically bind to the anti-P1' polyclonal antibody by dot immunobinding assay. Indirect ELISA showed that the synthesized 12-mer peptide could specifically bind to the serum of M. pneumoniae positive patients. The sensitivity and the specificity were 81.87% and 95%, respectively. These results indicated that HLQMRLTKLRMP might be a dominant epitope of the P1 and has the potential for serological diagnosis of M. pneumoniae.