ITIH4 and infection: These and previous data (Karasavvas et al., 2012) generated the hypothesis that IgG Abs to epitopes in both the V2 and V3 regions of gp120 are part of a complex interplay of immune responses that contributed to the reduced rate of infection in RV144 participants, and suggested that further delineation of additional elements of the V3 Ab response might reveal important information about the factors involved in blocking HIV infection.