Intranasal administration of unadjuvanted SARS‐CoV‐2 spike antigen boosts antigen‐specific immune responses induced by parenteral protein subunit vaccine prime in mice and hamsters

• DOI: 10.1002/eji.202350620
• Publication Date: 2024-04-02T05:49:15Z
• Authors: Gerard Agbayani; Bassel Akache; Tyler M. Renner; Anh Tran; Matthew Stuible; Renu Dudani; Blair A. Harrison; Diana Duque; Jegarubee Bavanan...; Lise Deschatelets; Usha D. Hemraz; Sophie Régnier; Yves Durocher; Michael J. McCluskie
• Keywords: Priming (agriculture); Heterologous

Abstract With the continued transmission of SARS‐CoV‐2 across widely vaccinated populations, it remains important to develop new vaccines and vaccination strategies capable providing protective immunity limiting spread disease. Heterologous prime‐boost based on selection different vaccine formulations administration routes for priming booster doses presents a promising strategy inducing broader immune responses in key systemic respiratory mucosal compartments. Intranasal can induce at site infection; however, lack clinically approved adjuvants makes difficult robust with protein subunit vaccines. Herein, we evaluated immunogenicity heterologous regimens mice hamsters parenteral antigen combination sulfated lactosylarchaeol (SLA) archaeosomes, liposome adjuvant comprised single semisynthetic archaeal lipid, followed by an intranasally administered unadjuvanted spike antigen. increased serum spike‐specific IgG titers spike‐neutralizing activity compared nonboosted animals. Spike‐specific IgA were also detected bronchoalveolar lavage fluid lungs that received intranasal boost. In hamsters, boost showed high efficacy against infection protecting from body weight loss reducing viral nasal turbinate. Overall, our intramuscular prime‐intranasal SLA‐adjuvanted spike, respectively, demonstrated potential promote antigen‐specific responses.