Syphilis is a sexually transmitted disease caused by Treponema pallidum subsp. pallidum; it can be effectively treated with penicillin yet remains prevalent worldwide, due in part to the shortcomings of current diagnostic tests. Here we report the production of soluble recombinant versions of three novel diagnostic candidate proteins, Tp0326, Tp0453, and a Tp0453-Tp0326 chimera. The sensitivities of these recombinant proteins were assessed by screening characterized serum samples from primary, secondary, and latent stages of infection (n ‫؍‬ 169). The specificities were assessed by screening false positives identified with the standard diagnostic testing algorithm (n ‫؍‬ 21), samples from patients with potentially cross-reactive infections (Leptospira spp., Borrelia burgdorferi, Helicobacter pylori, Epstein-Barr virus, hepatitis B virus, hepatitis C virus, or cytomegalovirus) (n ‫؍‬ 38), and samples from uninfected individuals (n ‫؍‬ 11). The sensitivities of Tp0326, Tp0453, and the Tp0453-Tp0326 chimera were found to be 86%, 98%, and 98%, respectively, and the specificities were 99%, 100%, and 99%. In a direct comparison, the Captia syphilis (T. pallidum)-G enzyme immunoassay (Trinity Biotech) was used to screen the same serum samples and was found to have a sensitivity of 98% and a specificity of 90%. In particular, Tp0453 and the chimera exhibited superior accuracy in classifying analytical false-positive samples (100%, compared to 43% for the Captia assay). These findings identify Tp0453 and the Tp0453-Tp0326 chimera as novel syphilis-specific diagnostic candidates that surpass the performance of a currently available diagnostic enzyme immunoassay test for syphilis and that allow accurate detection of all stages of infection.

suggests that phylotypes differ phenotypically. An accurate survey of genetic diversity and population structure will facilitate responsible selection of drug and/or vaccine targets for future treatments, and will enable better understanding of virulence factors contributing to the wide range of severity of symptoms associated with trichomoniasis. Objectives To develop a novel diagnostic protein in order to enhance early detection of syphilis infections and improve overall syphilis diagnosis. Methods Using pooled serum samples from patients infected with syphilis, immunoreactive regions of two previously identified diagnostic protein candidates, Tp0326 and Tp0453, were elucidated. Focusing on these regions, a chimeric protein construct was created for expression in Escherichia coli and expression conditions were optimised to produce soluble protein expression. This Tp0326/Tp0453 chimeric construct was screened against serum samples from; patients with primary, secondary, latent, and neurosyphilis and uninfected individuals. These results were directly compared to the rapid plasma regain (RPR) test, and the microhemagglutination assay for T pallidum (MHA-TP). P4-S3.08Results Screening results show high degrees of sensitivity and specificity for the Tp0326/Tp0453 chimeric construct, identifying all stages of syphilis infection from early primary to late latent. Conclusion The Tp0326/Tp0453 chimera shows promise as a new diagnostic antigen for detecting all stages of syphilis infection and for development into point-of-care diagnostic test formats. Objective Trichomonas vaginalis, a highly prevalent non-viral sexually transmitted infection, has been shown to be infected by a doublestranded RNA virus known as T vaginalis virus (TVV). The presence of this virus has been associated with increased trafficking of the immunogenic P270 to the surface of the parasite, and has therefore been hypothesised to be an important virulence factor in trichomoniasis. In the present study, we investigate the prevalence of TVV in globally distributed T vaginalis isolates and find an association between TVV infection and genetically distinct T vaginalis populations. Methods 150 T vaginalis isolates from the USA, Mexico, Italy, Southern Africa, Papua New Guinea and Australia were screened for TVV infection by running total RNA extract on 1% agarose gels to detect the presence or absence of the diagnostic 4.5 kb dsRNA genome of the virus. The prevalence of TVV in genetically distinct T vaginalis phylotypes was compared using c 2 tests. Results TVV was found to be present in 37% of T vaginalis isolates. We find a difference in the prevalence of TVV infection between genetically distinct populations of parasites, with 3% of phylotype 1 isolates containing the virus vs 73% of phylotype 2 parasites (<0.001). P4-S3.09 THE PREVALENCE OF TRICHOMONAS VAGINALISConclusions TVV prevalence varies between T vaginalis phylotypes 1 and 2. This finding has implications suggesting that TVV is transmitted vertically among parasites, as more closely relate...