Shared epitopes between Mycoplasma pneumoniae major adhesin protein P1 and a 140-kilodalton protein of Mycoplasma genitalium

Abstract

Previous serological data have demonstrated cross-reactive antigens between two pathogenic species of mycoplasmas, M. pneumoniae and M. genitalium. Preliminary analysis of sera and monoclonal antibodies (MAbs) to protein antigens of these species showed an immunodominance of adhesin P1 (165 kilodaltons [kDa]) of M. pneumoniae in mice and hamsters and a 140-kDa protein of M. genitalium in mice and experimentally infected chimpanzees. To further characterize these two proteins, we assayed multiple anti-Pl and anti-140-kDa protein MAbs by enzyme-linked immunosorbent assay, immunoblot, and radioimmunoprecipitation techniques. The 140-kDa M. genitalium protein was shown to be surface accessible and insensitive to levels of trypsin which readily degrade protein P1. Peptide mapping was used to identify a unique class of MAbs which bound a cross-reactive molecule common to both the major adhesin protein P1 of M. pneumoniae and the 140-kDa protein of M. genitalium. MAbs generated against both M. pneumoniae and M. genitalium which were reactive with this determinant blocked M. pneumoniae attachment to chicken erythrocytes. Mycoplasma pneumoniae and Mycoplasma genitalium are pathogens which share common ultrastructural, morphological, and serological features (3, 6, 9, 16, 17, 22, 25). In recent studies in our laboratory, various proteins of M. pneumoniae were identified as ligands mediating M. pneumoniae attachment to host cells (1, 2, 11, 13, 20). A trypsin-sensitive surface protein designated P1 (165 kilodaltons [kDa]) appears to be a primary ligand mediating cytadherence consistent with its dense clustering at the terminal nap region of the mycoplasma attachment organelle and its absence in specific nonadhering mycoplasma mutants (1, 8, 10, 12, 13). Moreover, monospecific and monoclonal antibodies (MAbs) to protein P1 of M. pneumoniae have been shown to block mycoplasma attachment to erythrocytes (RBCs) and respiratory epithelium (11, 20). Recent studies by Tully et al. (22, 23) have demonstrated that M. genitalium not only shares the flask shape of M. pneumoniae, but also possesses a predominant surface nap extending distally from the tip organelle. This structure appears to mediate the adherence of M. genitalium to Vero monkey kidney cell monolayers (22), thus implying that a process similar to that of M. pneumoniae regulates M. genitalium cytadherence. This study characterizes an immunodominant protein of M. genitalium with a molecular weight of 140,000. MAbs directed against both the 140-kDa protein and protein P1 of M. pneumoniae were used to examine the antigenic relatedness of these two proteins. Using this approach, a crossreactive epitope(s) on the two molecules was identified. MATERIALS AND METHODS Mycoplasma strains and culture conditions. Virulent, hemadsorbing M. pneumoniae M129-B16 was grown in 32-oz (946-ml) prescription bottles in 70 ml of Edward medium (7) at 37°C for 72 h. Glass-adherent mycoplasmas were washed four times with phosphate-buffered saline (PBS; pH 7.2) and collected by centrifugation (9,5...

mgpB and mgpC sequence diversity in Mycoplasma genitalium is generated by segmental reciprocal recombination with repetitive chromosomal sequences

“…Exhaustive studies mapping antibody-accessible epitopes within these proteins have not been performed, and reports concerning the location of MgPa-adherence epitopes are conflicting (Opitz and Jacobs, 1992;Svenstrup et al, 2002). Considering that both MgPa and P110 induce a humoral response in chimpanzees (Morrison-Plummer et al, 1987;Clausen et al, 2001;Svenstrup et al, 2006), men with acute urethritis (Morrison-Plummer et al, 1987;Clausen et al, 2001;Svenstrup et al, 2006), women with tubal-factor infertility (Morrison-Plummer et al, 1987;Clausen et al, 2001;Svenstrup et al, 2006), and women with lower tract M. genitalium infections (S.L. Iverson-Cabral and P.A.…”

Laboratory diagnosis of Mycoplasma pneumoniae infection

“…A main requirement with regard to the specificity of these ELISA tests is to avoid possible cross‐reactions with antibodies to Mycoplasma genitalium , the species most closely related to M. pneumoniae . The MgPa protein of M. genitalium (140 kDa) shows a high degree of similarity with the P1 protein of M. pneumoniae (169 kDa) [36]. Both proteins are important for cytoadherence, and the P1 protein is also the most potent immunogenic determinant of M. pneumoniae [37].…”

Cloning and sequence analysis of cytadhesin P1 gene from Mycoplasma pneumoniae

“…Mutants of M. pneumoniae which lack P1 or are unable to mobilize and anchor P1 at the tip are avirulent (1,15,16). Also, trypsin treatment of wild-type virulent mycoplasmas abrogates the functionality of P1 as an adhesin (1,2,10,11,23). Thus, it is well established that P1 is a critical virulence determinant but efforts to define structural-functional domains of this hydrophobic, integral membrane protein have failed.…”