ANTIGENICITY AND SPECIFICITY OF VERY-LOW MOLECULAR-WEIGHT ONCHOCERCA-VOLVULUS POLYPEPTIDES IN THE RANGE 2.2-12.5 KD

Onchocerca volvulus polypeptides in the molecular mass range of 2.2 to 12.5 kD were separated by Tricine-SDS-PAGE and the serological recogn ition of these very low molecular weight antigens (VLMW-OvAg) was then investigated by immune-blotting. Sera from 21 onchocerciasis patients as well as from 53 individuals with other filariases were used to det ermine the sensitivity and specificity of detection of individual VLMW -OvAg. In onchocerciasis patients, up to 16 VLMW-OvAg were recognized predominantly by IgG1 and IgG4, while only few antigens were recognize d by IgG2 and IgG3. The antigen recognition pattern varied individuall y, but 4 VLMW-OvAg of 8.6, 6.2, 5.4, and 5.1 kD, respectively, were bo und by IgG4 from more than 90% of the onchocerciasis patients. Six VLM W-OvAg of 7.3, 5.8, 5.4, 4.0, 3.8, and 3.6 kD were recognized exclusiv ely by IgG1 from onchocerciasis patients. In amicrofilaraemic filarias is patients with lymphatic pathology, a strong reactivity of IgG3 to a n OvAg of 2.2 kD was observed, indicating a possible contribution of t his antigen to the pathogenesis. In the molecular mass range below 13 kD, no specific carbohydrate residues or phosphorylcholine-containing (PC) determinants could be identified by lectin-blotting or PC-specifi c immunoblotting, respectively. Two-dimensional separation and immunob lotting distinctly reserved more than 40 antigenic polypeptides, the m ajority focusing at acidic isoelectric points. In O. volvulus-infected chimpanzees the IgG1- and IgG4-reactivity against OvAg below 13 kD ap peared concurrently with onset of patent infection. These data suggest that some of these VLMW-OvAg might be associated with the production and release of microfilariae from gravid female worms as well as be in volved in immune-mediated pathogenesis during filarial infections.