In order to determine the specificity of the anti-V3 mAbs generated from these three patients, we performed the ELISA binding titration of the anti-V3 mAbs with recombinant envelope gp120 proteins and HIV-1 derived peptides (Table 3 ). In addition to three Indian anti-V3 mAbs, which were generated in this study, we also tested the binding of an anti-V3 bNAb (447-52D), isolated from a subtype-B HIV-1 infected individual living in USA. The binding curves of mAbs to con-C and B V3 peptides and subtype-C (Du156.12) and B (JRFL) gp120 proteins are depicted in the representative Figure 1 . The mAbs were also tested with a series of peptides and proteins for quality control purpose and the 50% maximal binding (Max50) binding titers are summarized (Table 3) . Overall, the mAbs 277 and 903 showed binding to subtype-A or C V3 while the antibody 904 also reacted with subtype-B V3 region ( Figure 1A -B, Table 3 ). We further tested the mAbs by ELISA binding assays using Three anti-V3 monoclonal Abs listed were derived from HIV-1 infected Indian donors. 2 Immunoglobulin gene usage for heavy (IGHV) and amino acid sequences of 3 CDRH3 domains was determined using IMGT system; an asterisk indicates allele. Figure 1 Relative binding affinity of anti-V3 antibodies to HIV-1 derived peptides and proteins. The binding pattern of anti-V3 mAbs derived from Indian donors (red) and 447-52D (an anti-V3 Ab isolated from HIV-1 subtype-B infected American individual) (green) to consensus-C and B V3 peptides (1A), and subtype-C (Du156.12) and subtype-B (JRFL) derived envelope gp120 proteins (1B). The binding of anti-V3 mAbs was tested by ELISA using mAbs at a concentration ranging from 10 to 0.00003 μg/ml (12 dilutions). Human anti-parvovirus B19 mAb 1418 was used as negative control. Relative reactivity of anti-V3 plasma antibodies to consensus-B and C V3 peptides is shown in terms of 50% ELISA binding titers (Max50) for three patients from whom antibodies were generated (1C). Two plasma samples 277 and 904 showed cross clade reactive binding while 903 displayed subtype-C specific binding.