Advancing Prevention of STIs by Developing Specific Serodiagnostic Targets: <i>Trichomonas vginalis</i> as a Model

• Main Author: John F. Alderete
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: International Journal of Environmental Research and Public Health
• Subjects: diagnostic; diagnostic targets; ELISA-enzyme linked immunosorbent assay; epitopes; immunogens; sera
• Online Access: https://www.mdpi.com/1660-4601/17/16/5783

Point-of-Care (POC) serum antibody screening of large cohorts of women and men at risk for the sexually transmitted infection (STI) caused by <i>Trichomonas vaginalis</i> requires the availability of targets with high specificity. Such targets should comprise epitopes unique to <i>T. vaginalis</i> immunogenic proteins detected by sera of women and men patients with trichomonosis but not uninfected controls. Three enzymes to which patients make serum IgG antibody were identified as fructose-1,6-bisphosphate aldolase (A), α-enolase (E), and glyceraldehyde-3-phosphate dehydrogenase (G). Epitopes within these proteins were identified that had no sequence identity to enzymes of humans and other pathogens. Therefore, I constructed a chimeric recombinant String-Of-Epitopes (SOE) protein consisting of 15-mer peptides, within which are the epitopes of A, E, and G. This novel protein of ~36-kD is comprised of two epitopes of A, ten epitopes of E, and seven epitopes of G (AEG::SOE2). The AEG::SOE2 protein was detected both by immunoblot and by enzyme-linked immunosorbent assay (ELISA) using highly reactive sera of women and men but not negative serum unreactive to <i>T. vaginalis</i> proteins. Finally, AEG::SOE2 was found to be immunogenic, as evidenced by serum IgG from immunized mice. I discuss how this approach is important in relation to infectious disease diagnostic targets for detection of serum IgG antibody in exposed and/or infected individuals and how such novel targets may have potential as subunit vaccine candidates against microbial pathogens.