We also assessed the inhibition of NA activity by RVSE and a positive control oseltamivir carboxylate using various influenza viruses: H1N1 (A/PR/8/34 and A/Korea/33/2005), H3N2 (A/Korea/32/2005), and influenza type B (B/Korea/72/2006). The gene discussed is XK; the disease is influenza.