M. pneumoniae is elongated and consists of a longer tail-like rear end, a thicker body part and a frontal attachment organelle. Cytadherence requires a complex interaction of several M. pneumoniae proteins present on the attachment organelle, including the adhesins P1 (170 kDa), P30 (30 kDa), and P116 (116 kDa) RG7112 mw and proteins HMW1 to HMW3, as well as proteins A, B and C [4, 10–15]. Protein P1 and P30 appear to be directly involved in receptor binding [8, 16]. The HMW proteins and proteins A, B, and C are accessory proteins as they are not adhesins, but are required for proper attachment. The P1 protein, which is mainly

concentrated at the tip of apical organelle, is one of the major adhesins in M. pneumoniae as mutants lacking the P1 protein lose cytadherence and virulence capabilities [17, 18]. Vistusertib In addition, treatment of M. pneumoniae infection with anti-P1 antibodies has been shown to effect the gliding speed of M. pneumoniae, thus hampering the mobility of the bacterium and possibly its ability to find suitable host adhesion receptors [19]. Besides its role in M. pneumoniae cytadherence, P1 antigen is an important immunogen and is also being developed

as defined and specific antigen for the serodiagnosis of M. pneumoniae infection [20]. Previous reports and we have shown that a C-terminal region of P1 antigen can comparably diagnose M. pneumoniae infection taking the Methane monooxygenase Serion-Virion ELISA as the standard [14, 21]. Serum samples from patients Erismodegib chemical structure suffering from M. pneumoniae infection have also been shown to bind the peptide

fragments located in the middle of the ~170 kDa P1 antigens [22]. Since P1 is one of the major surface molecules on the apical organelles of M. pneumoniae, a number of studies have been performed to determine its immunogenicity as well as to characterize its role in adhesion/cytadherence. Using λgt11 recombinant DNA expression library of M. pneumoniae, Dallo et al. for the first time identified cytadherence (epitopes) at the C-terminal region of P1 gene [23]. Subsequently, in two independent studies based on topological mapping of the P1 binding sites, Gerstenecker et al. and Opitz et al. identified adherence associated region(s) across the length of P1 gene [11, 24]. Jacobs et al. further defined immunodominant epitopes of 338 amino acids between leucine 801 and leucine 1139 residues [25]. In 2002, Svenstrup et al. expressed P1 fragments lacking the tryptophan codon which codes for a stop codon in M. pneumoniae and identified adhesion epitopes in the C-terminal part of M. pneumoniae P1 gene using monospecific antibodies [14]. Although these above mentioned studies identified few adhesion/cytadherence segment(s) in M. pneumoniae P1 protein, a systematic study defining the region(s) involved in these processes across the entire length of P1 protein is lacking, therefore leading to contradicting results.