MAb HGN194, isolated from a donor infected with CRF02_AG clade, neutralized 11/20 pseudoviruses in the HOS-based assay and 19/92 pseudoviruses in the TZM-bl-based assay. Of note, HGN194 neutralized all Tier-1 isolates tested (10/10 neutralized) across clades A, B, C and recombinant AG and BC. Using Pepscan analysis with linear and cyclic peptide libraries of gp120 the epitope recognized by HGN194 was mapped to the sequence RRSVRIGPGQTF in the crown of the V3-loop ( Figure 4A) . Similarly, the epitope of 7 additional gp120specific mAbs was mapped to the same V3 region using different peptide libraries generated from the sequence of the isolate to which each mAb was mostly reactive ( Figure 4A) . The minimal sequence recognized by these mAbs ranged from 7 to 17 amino acids and, with a single exception, comprised the G(A)PGR/Q/K sequence, which is modeled to interact with CCR5 or CXCR4 during the viral entry process [63] . However, in contrast to HGN194 which neutralizes with high potency all Tier-1 isolates tested, the other V3-specific mAbs neutralized only a few Tier-1 isolates ( Figure 1A -B and Figure 2 ), similar to the activity of other recently characterized V3 loop-specific mAbs derived from non-B clade infected individuals [38] . We confirmed the neutralization activity of HGN194 in an M7 cell-based assay challenged with replication-competent HIV-1 viruses carrying a Luc reporter [52] and we observed that 3/5 clade B viruses were neutralized (Table S5) .