The present invention is a method of inhibiting the replication of an influenza virus by using an antiviral compound to inhibit the binding of an influenza-virus PB2 subunit to an RNA cap. The antiviral compound may be 5-iodo-2-[(3-methyl-4-nitrobenzoyl)amino]benzoic acid; 3,3′-[(4-methylphenyl)methylene]bis(4-hydroxy-2H-chromen-2-one); or 7-(4-hydroxy-2-oxo-2H-chromen-3-yl)-6H,7H,8Hchromeno[3,4′:5,6]pyrano[3,2-c]chromene-6,8-dione. The aforementioned antiviral compounds have successfully inhibited the replication of influenza virus in vitro and in vivo in mouse models.