Mycoplasma genitalium (MG) is a sexually-transmitted pathogen of men (urethritis) and women (cervicitis, pelvic inflammatory disease, ectopic pregnancy, infertility) with a similar prevalence as compared to Chlamydia trachomatis and Neisseria gonorrhoeae. Antibiotic resistance is increasing in MG, and some infections are untreatable with recommended regimens in the US. MG was included on the Watch List of the CDC 2019 Antimicrobial Threat Report, and was recognized as an understudied cause of PID at the November 2019 workshop ?New frontiers in STD-related PID, infertility, and other sequelae?. The recent FDA approval of two diagnostic tests will certainly increase public awareness of MG, and demands for improved treatments. Our laboratory has focused on understanding the ability of MG to persist for weeks to years despite the presence of specific antibodies in the genital tract, the variability of the immunodominant MgpB and MgpC adherence proteins, and the local and systemic antibody response to these proteins during infection. We demonstrated that MgpB and MgpC undergo phase and antigenic variation via a unique system of recombination between the mgpBC expression site and partial copies archived in the chromosome. In the parent grant (R21AI148816- 01), we extend these studies to define the epitopes and the consequences of antibody binding to the conserved and variable regions of MgpC. Further, we define the role of the newly identified MG281 antibody binding protein in evasion of the innate and specific immune response including binding to non-specific IgG and IgA, effect on MG complement resistance, and the effect of MG281 antibody binding on opsonophagocytic killing of MG. We hypothesize that MG281 protects MG from attack by innate defenses of the genital tract early in infection. As MgpB and MgpC are the dominant antigens targeted by patient antibodies, we further hypothesize that MG281 protects MG against killing by specific antibodies by preventing complement attack and opsonophagocytosis by genital tract immune cells. With this diversity supplement application, we seek support for an underrepresented minority pre-med, undergraduate student (Zoie Bailey) to expand upon Aims 2 and 3 of the parent award by identifying proteins that interact directly with MG281. Two types of interaction partners will be identified: (1) MG proteins that interact with MG281, and may augment its function, will be identified by co-immunoprecipitation of FLAG-tagged MG281, and (2) human serum proteins that bind recombinant MG281 will be identified by affinity chromatography. These proposed experiments complement our accompanying application in which we seek funding for a second undergraduate student (Victoria Bowman) as suggested by PA-18-906 who will identify functional domains within MG281. This project provides a unique opportunity for trainees to learn cutting- edge techniques applicable to many fields in biomedical research, contribute to our understanding of MG molecular pathogenesis, and receive training and mentoring as they begin careers in biomedical research.
The proposed studies seek to understand how Mycoplasma genitalium (MG), a sexually-transmitted bacterium, causes reproductive tract disease in men and women. MG avoids killing by the host immune response enabling persistence for weeks to years if untreated, and is increasingly resistant to antibiotics. Our studies will explore the interactions between MG surface molecules and host immune effectors including specific and non- specific antibodies, complement, and phagocytes.
