Mechanism of a COVID-19 nanoparticle vaccine candidate that elicits a broadly neutralizing antibody response to SARS-CoV-2 variants

Zhang, Yi-Nan; Paynter, Jennifer; Fourfouris, Tatiana; Sou, Cindy; Ngo, Timothy; He, Linling; Zhu, Jiang

Vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are essential for combating the coronavirus disease 2019 (COVID-19) pandemic. Neutralizing antibody responses to the original Wuhan-Hu-1 strain that were generated during infection and vaccination showed lower effectiveness against variants of concern. Here, we demonstrated that mouse plasma induced by protein nanoparticles that present rationally designed S2GΔHR2 spikes can neutralize the B.1.1.7, B.1.351, and P.1 variants with comparable titers. The mechanism of nanoparticle vaccine-induced immunity was examined in mice for an I3–01v9 60-mer that presents 20 stabilized spikes. Compared with the soluble spike, this nanoparticle showed 6-fold longer retention, 4-fold greater presentation on follicular dendritic cell dendrites, and 5-fold higher germinal center reactions in lymph node follicles. Intact nanoparticles in lymph node tissues were visualized by transmission electron microscopy. In conclusion, spike-presenting protein nanoparticles that induce robust long-lived germinal centers may provide a vaccine solution for emerging SARS-CoV-2 variants.