Designed mosaic nanoparticles enhance cross-reactive immune responses in mice.

Wang, Eric; Cohen, Alexander A; Caldera, Luis F; Keeffe, Jennifer R; Rorick, Annie V; Adia, Yusuf M; Gnanapragasam, Priyanthi N P; Bjorkman, Pamela J et al. · Cell · 2025

basic_science · Level V

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Abstract

Nanoparticle vaccines displaying combinations of SARS-like betacoronavirus (sarbecovirus) receptor-binding domains (RBDs) could protect against SARS-CoV-2 variants and spillover of zoonotic sarbecoviruses into humans. Using a computational approach, we designed variants of SARS-CoV-2 RBDs and selected 7 natural sarbecovirus RBDs, each predicted to fold properly and abrogate antibody responses to variable epitopes. RBDs were attached to 60-mer nanoparticles to make immunogens displaying two (mosaic-2<sub>COM</sub>s), five (mosaic-5<sub>COM</sub>), or seven (mosaic-7<sub>COM</sub>) different RBDs for comparisons with mosaic-8b, which elicited cross-reactive antibodies and protected animals from sarbecovirus challenges. Naive and COVID-19 pre-vaccinated mice immunized with mosaic-7<sub>COM</sub> elicited antibodies targeting conserved RBD epitopes, and their sera exhibited higher binding and neutralization titers against sarbecoviruses than mosaic-8b. Mosaic-2<sub>COM</sub>s and mosaic-5<sub>COM</sub> elicited higher antibody potencies against some SARS-CoV-2 variants than mosaic-7<sub>COM</sub>. However, mosaic-7<sub>COM</sub> elicited more potent responses against zoonotic sarbecoviruses and highly mutated Omicrons, supporting its use to protect against SARS-CoV-2 variants and zoonotic sarbecoviruses.

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