XK and influenza: We employed zanamivir as a representative of the anti-influenza NA inhibitors and measured the dose-dependent inhibition by zanamivir on neuraminidase activity of influenza viruses (A/Udorn/72(H3N2), A/Chiba/2009(H1N1)pdm and B/Johannesburg/99), S. pneumoniae and saliva, and on standard bacterial neuraminidases from A. ureafaciens and V. cholerae RDE (Figure 2A).