Fig. 6

The α-helical form of V1V2 potentially engages the α4β7 integrin with high efficacy. a Cell surface staining of HIV-1 infected CD4⁺ T cells (strains 92TH023 and CMU06) using RV144 mAbs CH58 (left) and CH59 (right). An uninfected control (top panels) was included to estimate background and showed minimal (<1%) staining of cells. Plots are shown as forward scatter (cell size indicator) vs. level of phycoerythrin conjugated staining of either mAb. b Endpoint ELISA binding titres of V2p mAbs CAP228-16H (green), CAP228-3D (orange) or CH59 (light blue), quaternary structure dependent V2q mAb PGT145 (purple) or V2i mAb 830 A (yellow) to concentrated pseudovirus expressing the C1080 envelope. HIV-1 CD4 binding site-specific antibody VRC01, and an irrelevant Flu-specific antibody were used as positive or negative controls, respectively. c Models of the HIV-1 prefusion Env trimer (left), misfolded/refolded helical V1V2 (centre) or gp160 that has adopted the CD4-bound conformation (right) are shown. The latter two conformations of Env display highly exposed α4β7 binding sites (gold spheres) within helical V1V2, providing a potentially functional role for aberrant Env on the viral surface in α4β7 integrin binding and viral dissemination