[W2-1] SARS-CoV-2 infection in oral cavity, saliva, and airway
COVID-19 has been a serious global health issue. Even though we have got vaccination and treatment options, understanding of transmissibility and tropism of SARS-CoV-2 is important to be prepared for emerging novel strains for which current vaccines and treatments are not as effective. We have created novel single-cell RNA sequencing atlases of oral cavity (gingiva and salivary glands) to identify cell types that express SARS-CoV-2 entry factors (ACE2 and TMPRSS family genes) as well as a comprehensive map of these markers in oral cavity using RNA in situ hybridization and immunohistochemical staining for clinical and autopsy specimens from non-COVID-19 and COVID-19 subjects, revealing that replicating SARS-CoV-2 virus exists in salivary glands and saliva. In vitro studies confirmed that saliva from COVID-19 subjects has transmissible and replicable viruses. These data suggest that oral cavity and saliva are important sites for virus infection, replication, and transmission, and that careful attention should be paid to these sites. In parallel, we have identified virus infectivity in nasal/oral-airway-lung axis and epithelial response to SARS-CoV-2 virus infection. SARS-CoV-2 infection caused mucus/mucin hyperproduction in sub-acute to chronic phases, which caused airway mucus obstruction in COVID-19.