Lateral flow-based antibody testing for Chlamydia trachomatis

Sarah Gwyn,Alexandria Mitchell,Deborah Dean,Harran Mkocha,Sukwan Handali,Diana L Martin

doi:10.1016/j.jim.2016.05.008

Abstract

We describe here a lateral flow-based assay (LFA) for the detection of antibodies against immunodominant antigen Pgp3 from Chlamydia trachomatis, the causative agent of urogenital chlamydia infection and ocular trachoma. Optimal signal detection was achieved when the gold-conjugate and test line contained Pgp3, creating a dual sandwich capture assay. The LFA yielded positive signals with serum and whole blood but not with eluted dried blood spots. For serum, the agreement of the LFA with the non-reference multiplex assay was 96%, the specificity using nonendemic pediatric sera was 100%, and the inter-rater agreement was κ=0.961. For whole blood, the agreement of LFA with multiplex was 81.5%, the specificity was 100%, and the inter-rater agreement was κ=0.940. The LFA was tested in a field environment and yielded similar results to those from laboratory-based testing. These data show the successful development of a lateral flow assay for detection of antibodies against Pgp3 with reliable use in field settings, which would make antibody-based testing for trachoma surveillance highly practical, especially after cessation of trachoma elimination programs.

Highlights

Trachoma, resulting from repeated infection with the bacterium Chlamydia trachomatis (Ct), is the leading global infectious cause of blindness
Serum samples were collected from a community in Nepal in 2000, 2002, or 2014 as part of a study of trachoma post-mass drug administration (MDA) serosurveillance (N = 432; age range 1–90 Gwyn et al, manuscript in preparation) that had been tested on a previously-described multiplex bead array (MBA) assay for antibodies against the Ct antigen Pgp3 (Goodhew et al, 2012, 2014; Martin et al, 2015b)
We describe here a lateral flow assay for detection of antibodies against the Ct antigen Pgp3 with good agreement compared to results from Pgp3 multiplex bead array testing and specificity against a panel of serum samples from children from a non-endemic country

Summary

Introduction

Trachoma, resulting from repeated infection with the bacterium Chlamydia trachomatis (Ct), is the leading global infectious cause of blindness. Blinding trachoma as a public health problem is targeted for elimination by 2020 using the SAFE strategy: Surgery for trichiasis, Antibiotics to treat infection, Facial cleanliness to prevent spread of infection, and Environmental improvement. Two years after stopping MDA, a survey is done to show continued TF levels b5%, which will provide the evidence for a dossier for validation of elimination of trachoma as a public health problem (“pre-validation survey”). In post-MDA settings where trachoma prevalence is low, the correlation between TF and active ocular infection breaks down (Mabey et al, 2003; Burton et al, 2011), in part because other pathogens can cause similar clinical signs (Dean et al, 2008; Capriotti et al, 2009; Dean et al, 2013)

Methods

Results

Conclusion