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    • Keywords


      Antiviral; H1N1 virus; mannose-binding lectin; Narcissus tazetta; RSV

    • Abstract


      Amannose-binding lectin (Narcissus tazetta lectin [NTL]) with potent antiviral activity was isolated and purified from the bulbs of the Chinese daffodil Narcissus tazetta var. chinensis, using ion exchange chromatography on diethylaminoethyl (DEAE)-cellulose, affinity chromatography on mannose–agarose and fast protein liquid chromatography (FPLC)-gel filtration on Superose 12. The purified lectin was shown to have an apparent molecular mass of 26 kDa by gel filtration and 13 kDa by SDS–PAGE, indicating that it is probably a dimer with two identical subunits. The cDNA-derived amino acid sequence of NTL as determined by molecular cloning also reveals that NTL protein contains a mature polypeptide consisting of 105 amino acids and a C-terminal peptide extension. Three-dimensional modelling study demonstrated that the NTL primary polypeptide contains three subdomains, each with a conserved mannose-binding site. It shows a high homology of about 60%–80% similarity with the existing monocot mannose-binding lectins. NTL could significantly inhibit plaque formation by the human respiratory syncytial virus (RSV) with an IC50 of 2.30 𝜇g/ml and exhibit strong antiviral properties against influenza A (H1N1, H3N2, H5N1) and influenza B viruses with IC50 values ranging from 0.20 𝜇g/ml to 1.33 𝜇g/ml in a dose-dependent manner. It is worth noting that the modes of antiviral action of NTL against RSV and influenza A virus are significantly different. NTL is effective in the inhibition of RSV during the whole viral infection cycle, but the antiviral activity of NTL is mainly expressed at the early stage of the viral cycle of influenza A (H1N1) virus. NTL with a high selective index (SI=CC50/IC50 ≥ 141) resulting from its potent antiviral activity and low cytotoxicity demonstrates a potential for biotechnological development as an antiviral agent.

    • Author Affiliations


      Linda S M Ooi1 Wing-Shan Ho1 Karry L K Ngai2 Li Tian1 3 4 Paul K S Chan2 5 Samuel S M Sun1 4 Vincent E C Ooi1

      1. Departments of Biology, The Chinese University of Hong Kong, Shatin, N T, Hong Kong, China
      2. Departments of Microbiology, The Chinese University of Hong Kong, Shatin, N T, Hong Kong, China
      3. Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
      4. Life Science Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
      5. Departments of Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Shatin, N T, Hong Kong, China
    • Dates

  • Journal of Biosciences | News

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