SARS‐CoV‐2 nucleocapsid protein intranasal inoculation induces local and systemic T cell responses in mice

SARS‐CoV‐2 nucleocapsid (N) protein has been proposed as a good vaccine target. N‐specific T cells were observed in SARS‐CoV‐2 N immunized mice and COVID‐19 convalescents. It is of importance to identify the T cell responses triggered by SARS‐CoV‐2 N protein. Intradermal immunization with SARS‐CoV N protein was demonstrated to elicit non‐protective T cell responses which may be avoided by intranasal vaccination. Therefore, we conducted intranasal vaccination of BALB/c mice with recombinant adenovirus type‐5 expressing SARS‐CoV‐2 N protein. Such procedure induced CD8 T cell responses in the lung. Meanwhile CD4 T cell responses were observed in the spleen, which was associated with robust antibody production. Our study further supports the notion that SARS‐CoV‐2 N protein can work as a target for vaccine development.