Onchocerca Diagnostic Testing of Polymorphisms; Effects of Antigenic Mutations on Detection of Antibodies by OV-16 ELISA

Onchocerca is a filarial parasite transmitted to humans by the female blackfly of the Simulium genus that is known to cause “river blindness” among humans in regions of Africa and the Americas. ELISA (Enzyme-linked Immunosorbent Assay) serological testing for the presence of antibodies to a diagnostic antigen (Ov16) is a diagnostic tool in current use for verifying suppression of transmission of the parasite. Recently a humanized monoclonal antibody has been developed to use as a positive control in the Ov16 ELISA. This was done as it is becoming harder to obtain positive samples for use as pooled sera for a source of positive controls as elimination grows closer. Recently we have discovered that naturally occurring polymorphisms in the Ov16 antigen affect the binding of this monoclonal antibody. Here, we have identified the particular polymorphism responsible for the loss of monoclonal antibody reactivity and investigated the potential effect these polymorphisms may have on the sensitivity of the Ov16 ELISA for the detection of parasite exposure.