ABSTRACT
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.
ABSTRACT
Inflammasomes are cytosolic multiprotein complexes that sense microbial motifs or cellular stress and stimulate caspase-1-dependent cytokine secretion and cell death. Recently, it has become increasingly evident that both DNA and RNA viruses activate inflammasomes, which control innate and adaptive immune responses against viral infections. In addition, recent studies suggest that certain microbiota induce inflammasomes-dependent adaptive immunity against influenza virus infections. Here, we review recent advances in research into the role of inflammasomes in antiviral immunity.
