Fig. 8.

Localization of the gp-41 binding site on the A-chain of C1q.

Various peptides from selected regions of the A-chain of C1q were synthesized and 100 μl of 1 mg/ml of each was coated onto ELISA wells in duplicates following the standard ELISA described above. After blocking, 100 μl of either 5 μg/ml of gC1qR or 200 μg/ml of gp41-3S were added and incubated overnight at 4 °C. After removal of the excess unbound reactants and washing, the bound gC1qR and gp41-3S were detected using mAb 74.5.2 or anti-gp41-3S antibody respectively, following standard ELISA procedure. The designation QQ (residues 155–164) indicates that two Q residues at positions 162 and 163 substituted the two R residues. The significance of binding of gp41-3S to C1q peptide 14–16 was (p ≤ 0.05; n = 3) whereas to 76–92 was (p ≤ 0.001).