To test the serpin-like properties and antiviral activities of our Spn4A variants in cellulo, recombinant adenoviruses (Ad) expressing the Spn4A constructs Ad-Spn4A.RRLL(r) and Ad-Spn4A.RRLL(s) were produced as described previously [55] . As adenoviruses display strong tropism for the liver [60] , the major site of HCV infection [13] , these recombinant adenoviruses are especially useful molecular tools for HCV research, including the use of human hepatoma Huh-7.5.1 cells, which support robust HCV infection in cellulo [61] .