Construction of a Human Cell Landscape of COVID-19 Infection at Single-cell Level.

COVID-19 is now causing a global pandemic, there is a demand to explain the different clinical patterns between children and adults. To clarify the organs/cell types vulnerable to COVID-19 infection and the potential age-depended expression patterns of five factors (ACE2, TMPRSS2, MTHFD1, CTSL, CTSB) associated with clinical symptoms. In this study, we analyzed expression levels of five COVID-19 host dependency factors in multiple adult and fetal human organs. The results allowed us to grade organs at risk and also pointed towards the target cell types in each organ mentioned above. Based on these results we constructed an organ- and cell type-specific vulnerability map of the expression levels of the five COVID-19 factors in the human body, providing insight into the mechanisms behind the symptoms, including the non-respiratory symptoms of COVID-19 infection and injury. Also, the different expression patterns of the COVID-19 factors well demonstrate an explanation that the different clinical patterns between adult and children/infants.