Drug discovery screens can target an enzyme unique to the pathogen and quickly sort out promising inhibitors of that enzyme. Yuan, S. et al. targetted the endonuclease function of the RNA-dependent RNA polymerase of influenza A in their screening. The screen identified the small molecule compound ANA-0 as a replication inhibitor of multiple types of influenza in cell culture including H1N1, commonly known as the Swine Flu, and H5N1, commonly known as Bird Flu. ANA-0 also showed synergistic anti-influenza effects in vitro with antiviral drug zanamivir.

Read more here: http://www.nature.com/articles/srep22880