Figure 2

Binding of anti-V3 mAbs to native viruses. Binding of anti-V3 MAbs to native, intact HIV-1 virions, Du156.12 (subtype-C) and JRFL (subtype-B). The supernatants of the two viruses were used at a final p24 concentration of 25 ng/ml. Antibody 904 displayed binding to both viruses (Du156.12 and JRFL), while antibodies 277 and 903 showed subtype-C (Du156.12) specific binding (A). The unrelated mAb 1418 against parvovirus B19 served as a negative control.The anti-V3 mAb 447-52D (known to bind SF162, a clade-B virus) and SF162 were used to validate the experiment. The binding of 447-52D to intact virus was performed by using a fixed concentration of antibody (10 μg/ml) with two-fold dilution of SF162 virus starting with 50 ng/ml of virus (B). The virus capture is determined by measuring the level of p24 (picograms per milliliter) released when bound virus is lysed with detergent. The viruses (Du156.12 and JRFL) were chosen for intact virion binding assay on the basis of their resemblance to the consensus-B and C V3 loop sequences (C). The V3 sequence of these viruses is aligned with their corresponding consensus-C and B V3 loop sequence using Seqpublish program (http://hiv.lanl.gov).