Molecular Point-of-Care diagnostic for Treponema pallidum subsp. pertenue (yaws)
thesisposted on 14.05.2019, 14:52 by Laud Anthony Basing
The eradication of yaws a neglected tropical disease caused by Treponema pallidum subsp. pertenue, which affects children living in very deprived hard to reach rural communities is constrained by the lack of rapid, accurate diagnosis. I sought to develop a molecular point-of-care test for the diagnosis of yaws. A Loop-mediated isothermal amplification (LAMP) assay with primers targeting the conserved gene, tp0967, with visual detection by lateral flow test strip was developed and optimized. The limit of detection was evaluated while 63 samples from clinical cases of yaws and 5 samples with PCR-confirmed syphilis were used to determine the sensitivity and specificity of the assay compared to the current molecular testing protocol. Reagents were dried in tubes and tested up to 14 days. The developed LAMP assay was found to be optimal when run at 65oC in a water bath for 30 minutes. The limit of detection was 2.7*104 DNA copies/ml. The sensitivity of the LAMP assay using unextracted and DNA extracted samples were 0.67 and 1.00 respectively. None of the syphilis samples tested positive in any of the assays. We show the development of a fast and sensitive LAMP assay for yaws detected by lateral flow test strip. Using extracted DNA, the assay sensitivity is at par with gold standard detection. The assay can be adapted to minimal sample processing required for in-field detection without DNA extraction.