Fig. 4: Ad26 encoding HIV-1 Env can boost particle prime induced antibody responses.

a Antigenic binding profile of a trivalent mixture of Ad26.RnS.Env, encoding membrane-expressed clade C ConC, sC4, and C97ZA. Binding to a panel of broadly neutralizing antibodies (bNAbs) (2G12, PGT128, VRC26, and PGDM1400) and non-bNAbs (F105, b6, 14e, and 17b) was assessed by flow cytometry. CR9506 antibody was used as an isotype control. Bars represent average ± standard deviation (SD) of n = 2 technical replicates (open circles). b Schematic of Ad26 boost phase; the Env-CoP2 and control groups (highlighted boxes) were immunized with Ad26.RnS.Env or buffer respectively, at week 34 and blood sampling for immunogenicity was done two weeks later at week 36. c Direct ELISA titers of immunized animals against the ConC gp140 trimer to detect all binding antibodies in the Ad26 boost phase at weeks 34 and 36 in comparison to week 18. d Capture ELISA titers against the ConC gp140 trimer to detect antibodies binding to conformational epitopes in the Ad26 vs. particle immunization phases. Bars in c, d represent median with 95% confidence interval (CI) for individual rabbits within the Env-CoP2-Ad26 (N = 9) and control (N = 4) groups, dotted lines represent the ELISA assay LLOD and numbers at the bottom of the graphs denote median values. Source data are provided as a Source Data file.