Integrating multiple biomarkers to increase sensitivity for the detection of Onchocerca volvulus infection

: Serological assessments for human onchocerciasis are based on IgG4 reactivity against the OV-16 antigen, with sensitivity around 60-80%. We previously identified 7 novel proteins that could enhance onchocerciasis sero-diagnosis. Further screening by luciferase immunoprecipitation assays identified OVOC10469 and OVOC3261 as the most promising candidates. IgG4-based ELISA using recombinant proteins, yielded sensitivities of 53% for rOVOC10469 and 78% for rOVOC3261, while specificity for each was >99%. Moreover, the newly-identified biomarkers detected some (but not all) of the mf-positive samples not detected by OV-16. The new antigens in combination with OV-16, increased the sensitivity for patent infections to 94%, demonstrating the benefits of adding a complementary antigen to OV-16-based serology. The kinetics of appearance of these IgG4 responses based on experimentally infected non-human primates indicated that they were patency driven. Of note, the IgG4 responses to both OVOC10469 and OVOC3261 (as well as to OV-16) drop significantly (p<0.05) following successful treatment for onchocerciasis. A prototype of a lateral flow rapid assay was developed and tested, showing an overall 94% sensitivity. These data showed that the combined use of rOVOC3261 with OV-16 improved case detection, a current and urgent need for the efforts to achieve the worldwide elimination of transmission of O. volvulus.