The Ab accessibility on the HIV-1 native virus is often challenged by the glycosylation pattern and epitope masking [39, 62, 63] . This effect has been particularly recognized for the V3 region wherein the neighboring regions including V1/V2 shield the epitopes recognized by anti-V3 Abs [46] . Although studies have suggested that the HIV-1 V3 loop remains accessible on most of the viruses [36] , however this information is limited to subtype-B viruses and remains to be explored for other subtypes. Consistent with the binding to gp120 proteins (Du156.12 and JRFL), the three anti-V3 mAbs were able to bind intact native virions with a similar binding pattern (Figure 2A) . The results suggest that V3 epitopes are well exposed over the intact trimeric viruses (Du156.12 and JRFL), and these findings are highly supported by previous work in the literature [36, 43] . The rationale of using same proteins (gp120) and its corresponding viruses (intact virion) for the binding assays was to minimize the effect of both, the V3 loop sequence and the neighboring regions, on the local and global orientation of V3 and on the subsequent binding of Abs.