A Triad Approach Towards Improved Diagnostics for Maternal and Congenital Syphilis

Project Summary
Syphilis is a sexually and vertically transmitted disease caused by Treponema pallidum subspecies pallidum
(TPA). While adult syphilis is often asymptomatic and self-resolving, congenital syphilis – fetal infection during
pregnancy – can cause birth defects and neonatal death. Since 2017, syphilis has climbed 170% in reproductive
age women and 203% among newborns. Syphilis is treatable with penicillin, but timely maternal and newborn
diagnosis remains a complex social and scientific problem. Polymerase chain reaction (PCR) can detect TPA in
newborns and in adult chancres from initial (primary syphilis) and sores from subsequent flu-like (secondary
syphilis) stages. But poverty, abusive relations, and information gap often prevent women from seeking timely
care while high cost, long turnaround time and lack of knowledge diminishes clinical uptake. Pregnant patients
often present in asymptomatic latent (late) syphilis stage when PCR has low sensitivity in peripheral blood, saliva,
and urine. Meanwhile, studies have not looked at specimens, such as vaginal fluids, interfacing the uterine
environment, which we hypothesize, are more likely to contain elevated TPA and correlated microbiome
biomarkers for development of novel maternal diagnostics. Immunoassays also have poor sensitivity and
specificity and require physical exam and treatment data. New molecular tests that make diagnosis easier, faster,
more reliable, and accessible are urgently needed to fight the syphilis epidemic and prevent congenital infections.
Our goal is to address this need using a triad approach where in Aim 1 we will develop a point-of-care nucleic
acid test (POC NAT) and automate it on microfluidic rapid and autonomous analytical devices (microRAAD) with
colorimetric readout. Without complex instruments, this POC NAT will allow rapid detection of congenital syphilis
in neonatal peripheral blood and would be reconfigurable for adult swab self-testing. By using engineered DNA
polymerases for amplification of multiple genes (sensitive) with sequence decoding strand exchange probes that
will logically calculate an integrated colorimetric signal (specific) on a lateral flow dipstick (practical), our test
should be more sensitive, more specific, faster, and more easily adapted to POC use than anything currently
available. To ensure wide reach and uptake of this diagnostic, we will perform early end user assessment of
feasibility, acceptability, usability, and implementation preferences (Aim 3). Finally, to enable new maternal
syphilis diagnostics, we will evaluate TPA detectability and microbiome perturbation in maternal vaginal self-
swabs (Aim 2). Our Aims are highly achievable because we have a history of collaboration, in-depth expertise,
validated assay and device technologies, and public health nexus with sexual healthcare. The resulting data
would facilitate future clinical validation and translation into practice via Early Translational Research Awards
and industry partnerships for manufacturing. Taken together, by making syphilis diagnosis easier, more accurate,
and accessible, this research will make a significant impact on congenital syphilis prevention. Moreover, this
robust approach to fast and accurate pathogen detection can be readily diversified to a wider array of pathogens.

Grant Number: 5R21AI185965-02
NIH Institute/Center: NIH
Principal Investigator: Sanchita Bhadra