Tandem use of OvMANE1 and Ov-16 ELISA tests increases the sensitivity for the diagnosis of human onchocerciasis

The current serological test for human onchocerciasis relies on IgG4 reactivity against the parasite Ov-16 antigen, with reported sensitivities of only 60-80%. It is therefore imperative to identify novel molecules that could improve the serodiagnosis reliability of this disease. In this study we compared the sensitivity of total IgG against OvMANE1 chimeric antigen with that of Ov-16 test to detect an Onchocerca volvulus infection in persons presenting with microfilaria in skin snips. From the 190 onchocerciasis serum samples obtained, 59 (31.1%) samples were from individuals with a positive skin snip test; 41 (69.5%) of these 59 samples were positive with the OvMANE1 test and 41 (69.5%) with the Ov-16 test; 30 (50.8%) samples were positive for both tests and in 52 (88.1%) at least one of the tests was positive. Testing the 131 sera from persons with a negative skin snip result revealed that 63 (48.1%) were positive exclusively with the OvMANE1 test, 13 (9.9%) exclusively with the Ov-16 test and 25 (19.1%) with both tests. Nine European samples and 15 Rwandan samples from an onchocerciasis non-endemic area were all negative for the OvMANE1 and Ov-16 tests. However, the specificity of both tests was difficult to determine due to the lack of a gold standard for antibody tests. In conclusion, the tandem use of OvMANE1 and Ov-16 tests improves the sensitivity of Onchocerca volvulus infection detection but, the OvMANE1 test needs to be further evaluated on samples from a population infected with other helminths to address its specificity.