The VRC01-class of potent, broadly neutralizing antibodies (bnAbs) targets the conserved CD4-binding site (CD4bs) of HIV-1 Env which has been a major target of HIV-vaccine design. The current best priming immunogen to engage the VRC01-class germline precursors is the eOD-GT8 60mer, which elicits VRC01-class precursors in multiple transgenic mouse models. However, a large proportion of the antibodies elicited by eOD-GT8 60mer are non-CD4bs or “off-target” antibodies, undermining its effectiveness in eliciting the VRC01-class bnAb precursors.

Researchers at the Vaccine Research Center (VRC) of the National Institute of Allergy and Infectious Diseases introduced multiple N-linked glycosylation sites to mask non-CD4bs regions of eOD-GT8 60mer to focus the antibody immune response to the CD4bs.

Several glycan-masked mutants showed significantly decreased antibody binding to non-CD4bs “off-target” epitopes while maintaining strong binding to CD4bs-specific bnAbs. Furthermore, in vivo studies showed that immunization with the best glycan-masked eOD-GT8 mutants resulted in significant increases in the elicitation of CD4bs-specific serum antibodies, CD4bs-specific B cells in the spleen, and VRC01-class precursors, compared to immunization with the parental eOD-GT8 immunogen. In conclusion, because of their improved antigenic and immunogenic profiles, glycan-masked eOD-GT8 60mer mutants may serve as improved priming immunogens to elicit VRC01-class bnAbs in humans.