For example, TMPRSS2-KO mice were protected from pulmonary disease and death following H1N1 and H7N9 Influenza infection, but not from that of the influenza H3N2 subtype, demonstrating some specificity and showing also that other TTSP proteases [such as DESC1 (TMPRSS11E) and MSPL (TMPRSS13)] or other factors may be important (44–47). This evidence concerns the gene TMPRSS2 and influenza.