Detection of antibodies to the α4β7 integrin binding site on HIV-1 gp120 V2 loop using a novel cell adhesion assay

Background The gut mucosal homing integrin receptor a4b7 present on activated CD4+ T-cells interacts with the HIV-1 gp120 second variable loop (V2). Case control analysis of the RV144 phase III vaccine trial showed that antibodies induced by the vaccine bound to a MuLV-gp70 scaffolded V1V2 loop of gp120 (V1V2-gp70) and correlated inversely with infection. These, and other data, generate the hypothesis that the vaccine-elicited antibodies may have been involved in limiting HIV-1 acquisition. We have developed a high-throughput assay to evaluate antibodies that block a4b7 binding. We have named this the RAP assay.