IFITM proteins promote SARS-CoV-2 infection and are targets for virus inhibition in vitro

Over-expression of interferon-induced transmembrane proteins (IFITMs 1, 2 and 3) blocks SARS-CoV-2 infection in Calu-3 cells. However, endogenous IFITM expression supports efficient infection of SARS-CoV-2 in primary cultured human lung cells.  SARS-CoV-2 spike protein interacts with IFITMs, which plays an important role for supporting viral infection. IFITM proteins were expressed and further induced by interferon treatment in human lung, gut, heart and brain cells. IFITMs are co-factors for efficient SARS-CoV-2 infection in human cells.