Human isotype antibody responses to an Onchocerca volvulus glutathione S-transferase

Human isotype specific antibody responses to a recombinant pi-class glutathione S-transferase (Ov24) from Onchocerca volvulus were assessed by ELISA, using a large and well-characterized bank sera (n = 238) from an hyper-endemic area of moderate intensity from Sierra Leone. IgG1, IgG4 and IgA responses, but neither IgG2 nor IgE response, to Ov24 were detected in infected subjects. The relationships between Ov24 antibody levels and skin microfilarial density, number of nodules, age, sex, eosinophil counts and clinical sign of reactive and chronic pathology were analysed using Pearson's correlation coefficient. Significant correlations between both IgA and IgG3 antibody levels and age were found (P < 0.01). Although no firm conclusions could be drawn from this study sample regarding the relationships between antibody levels and parasite load or clinical status, a negative correlation (P = 0.06) between Ov24 IgG3 antibody levels and microfilarodermia was found.