Intranasal SARS-CoV-2 spike-based immunisation adjuvanted with polyethyleneimine elicits mucosal and systemic humoral responses in mice

J Immunol Methods. 2022 Dec;511:113380. doi: 10.1016/j.jim.2022.113380. Epub 2022 Oct 25.

Abstract

The SARS-CoV-2 pandemic continues despite the presence of effective vaccines, and novel vaccine approaches may help to reduce viral spread and associated COVID-19 disease. Current vaccine administration modalities are based on systemic needle-administered immunisation which may be suboptimal for mucosal pathogens. Here we demonstrate in a mouse model that small-volume intranasal administration of purified spike (S) protein in the adjuvant polyethylenemine (PEI) elicits robust antibody responses with modest systemic neutralisation activity. Further, we test a heterologous intranasal immunisation regimen, priming with S and boosting with RBD-Fc. Our data identify small volume PEI adjuvantation as a novel platform with potential for protective mucosal vaccine development.

Keywords: Adaptive immunity; COVID-19; Mucosal adjuvant; RBD; SARS-CoV-2; Spike; Vaccine.