TY - JOUR T1 - Disruption of nasal bacteria enhances protective immune responses to influenza A virus and SARS-CoV-2 infection in mice JF - bioRxiv DO - 10.1101/2020.12.25.424300 SP - 2020.12.25.424300 AU - Minami Nagai AU - Miyu Moriyama AU - Takeshi Ichinohe Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/12/27/2020.12.25.424300.abstract N2 - Gut microbiota plays a critical role in the induction of adaptive immune responses to influenza virus infection. However, the role of nasal bacteria in the induction of the virus-specific adaptive immunity is less clear. Here we demonstrate that while intranasal administration of influenza virus hemagglutinin vaccine alone was insufficient to induce the vaccine-specific antibody responses, disruption of nasal bacteria by lysozyme or addition of culturable oral bacteria from a healthy human volunteer rescued inability of the nasal bacteria to generate antibody responses to intranasally administered the split-virus vaccine. Myd88-depdnent signaling in the hematopoietic compartment was required for adjuvant activity of intranasally administered oral bacteria. In addition, we found that the oral bacteria-combined intranasal vaccine induced protective antibody response to influenza virus and SARS-CoV-2 infection. Our findings here have identified a previously unappreciated role for nasal bacteria in the induction of the virus-specific adaptive immune responses.Competing Interest StatementThe authors have declared no competing interest. ER -