Focal accumulation of aromaticity at the CDRH3 loop mitigates 4E10 polyreactivity without altering its HIV neutralization profile.

Broadly neutralizing antibodies (bnAbs) against HIV-1 are frequently associated with the presence of autoreactivity/polyreactivity, a property that can limit their use as therapeutic agents. The bnAb 4E10, targeting the conserved Membrane proximal external region (MPER) of HIV-1, displays almost pan-neutralizing activity across globally circulating HIV-1 strains but exhibits nonspecific off-target interactions with lipid membranes. The hydrophobic apex of the third complementarity-determining region of the heavy chain (CDRH3) loop, which is essential for viral neutralization, critically contributes to this detrimental effect. Here, we have replaced the aromatic/hydrophobic residues from the apex of the CDRH3 of 4E10 with a single aromatic molecule through chemical modification to generate a variant that preserves the neutralization potency and breadth of 4E10 but with reduced autoreactivity. Collectively, our study suggests that the localized accumulation of aromaticity by chemical modification provides a pathway to ameliorate the adverse effects triggered by the CDRH3 of anti-HIV-1 MPER bnAbs.