Preliminary Evaluation of the Diagnostic Performance of OvMANE1 and OvMCBL02 Multiepitope Antigens for the Non-Invasive Diagnosis of Onchocerciasis Exposure

A shift in the public health goal for onchocerciasis from control to elimination implies that the treatment of onchocerciasis must be extended to communities that are hypoendemic for the disease. However, in such communities, the majority of the population may not manifest the symptoms of onchocerciasis. As a result, they may be reluctant to take part in epidemiological surveys aimed at monitoring parasite transmission, particularly due to the invasive nature of the currently approved diagnostic tests. This reluctance is compounded by the absence of visible, severe manifestations of the disease in these areas. On the other hand, diagnostic methods that utilize samples collected by a non-invasive procedure, such as urine, are generally painless and not risky. In this context, we evaluated the diagnostic performances of OvMANE1 and OvMCBL02 multiepitope antigens using urine samples. The evaluation of total IgG and IgG subclass responses revealed IgG3 as the most effective IgG for the OvMANE1 test (sensitivity = 87.5%, specificity = 100.0%), total IgG for the OvMCBL02 test (sensitivity = 92.5%, specificity = 100.0%), and IgG3 for the OvMANE1_OvMCBL02 cocktail test (sensitivity = 92.5%, specificity = 100.0%). These tests have the potential to meet the criteria of a diagnostic test's target product profile to map onchocerciasis in low-prevalence areas, where a sensitivity of ≥60.0% and specificity of ≥99.8% are recommended. Furthermore, the OvMCBL02 and OvMANE1_OvMCBL02 cocktail tests may have the features of a diagnostic test's target product profile to determine treatment endpoints (recommended sensitivity ≥ 89.0%, specificity ≥ 99.8%) as reported by the Diagnostics Technical Advisory Group for Neglected Tropical Diseases of the World Health Organization. Consequently, further characterization of these multiepitope antigens may enable urine, which can be collected non-invasively, to be used in the OvMANE1 and OvMCBL02 tests for the field evaluation of onchocerciasis.