Influenza epidemics and pandemics are caused by influenza A virus. The cell surface protein of hemagglutinin and neuraminidase is responsible for viral infection and release of progeny virus on the host cell membrane. Now 18 hemagglutinin and 11 neuraminidase subtypes are identified. The avian influenza virus of H5N1 is an emergent threat to public health issues. To control the influenza viral infection it is necessary to develop antiviral inhibitors and vaccination. In the present

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... we carried out 50 ns Molecular Dynamics simulation on H5 hemagglutinin of Influenza A virus H5N1 complexed with fluorinated sialic acid by substituting fluorine atoms at any two hydroxyls of sialic acid by considering combinatorial combination. The binding affinity between the protein–ligand complex system is investigated by calculating pair interaction energy and MM-PBSA binding free energy. All the complex structures are stabilized by hydrogen bonding interactions between the H5 protein and the ligand fluorinated sialic acid. It is concluded from all the analyses that the fluorinated complexes enhance the inhibiting potency against H5 hemagglutinin and the order of inhibiting potency is SIA-F9 ≫ SIA-F2 ≈ SIA-F7 ≈ SIA-F2F4 ≈ SIA-F2F9 ≈ SIA-F7F9 > SIA-F7F8 ≈ SIA-F2F8 ≈ SIA-F8F9 > SIA-F4 ≈ SIA-F4F7 ≈ SIA-F4F8 ≈ SIA-F8 ≈ SIA-F2F7 ≈ SIA > SIA-F4F9. This study suggests that one can design the inhibitor by using the mono fluorinated models SIA-F9, SIA-F2 and SIA-F7 and difluorinated models SIA-F2F4, SIA-F2F9 and SIA-F7F9 to inhibit H5 of H5N1 to avoid Influenza A viral infection. Communicated by Ramaswamy H. Sarma