In the new study, posted Oct. 27 to the preprint database medRxiv, researchers predicted which mouth tissues might be most vulnerable to SARS-CoV-2, the virus that causes COVID-19. So the team examined RNA — a kind of genetic material that tells the cells’ protein-making factories what to build — for different cell types in the mouth. They found that, compared with other oral tissues, cells of the salivary glands, tongue and tonsils carry the most RNA linked to proteins that the coronavirus needs to infect cells. The more virus they found, the more likely a given patient had smell and taste loss as one of their symptoms, although saliva from several asymptomatic people also contained infected cells. Theoretically, SARS-CoV-2 infection in the mouth could cause changes in saliva production or quality, contributing to symptoms of taste loss, he said. Future research could reveal how this mouth infection affects the course of illness in COVID-19 patients, as well as how those infected cells contribute to the spread of the coronavirus between people Specifically, they created an atlas of different cells in the mouth, which essentially serves as a map of which cells contain what RNA, and where. “This new atlas provided us a way to analyze 50 oral cell types … at once for the common ‘front doors’ the virus uses to enter cells for infection,” Byrd said.