title: Inhibition of hepatitis C virus by the cyanobacterial protein Microcystis viridis lectin: mechanistic differences between the high-mannose specific lectins MVL, CV-N, and GNA.
abstract: Plant or microbial lectins are known to exhibit potent antiviral activities against viruses with glycosylated surface proteins, yet the mechanism(s) by which these carbohydrate-binding proteins exert their antiviral activities is not fully understood. Hepatitis C virus (HCV) is known to possess glycosylated envelope proteins (gpE1E2) and to be potently inhibited by lectins. Here, we tested in detail the antiviral properties of the newly discovered Microcystis viridis lectin (MVL) along with cyanovirin-N (CV-N) and Galanthus nivalis agglutinin (GNA) against cell culture HCV, as well as their binding properties toward viral particles, target cells, and recombinant HCV glycoproteins. Using infectivity assays, CV-N, MVL, and GNA inhibited HCV with IC50 values of 0.6 nM, 30.4 nM, and 11.1 nM, respectively. Biolayer interferometry analysis demonstrated a higher affinity of GNA to immobilized recombinant HCV glycoproteins compared to CV-N and MVL. Complementary studies, including fluorescence-activated cell sorting (FACS) analysis, confocal microscopy, and pre- and post-virus binding assays, showed a complex mechanism of inhibition for CV-N and MVL that includes both viral and cell association, while GNA functions by binding directly to the viral particle. Combinations of GNA with CV-N or MVL in HCV infection studies revealed synergistic inhibitory effects, which can be explained by different glycan recognition profiles of the mainly high-mannoside specific lectins, and supports the hypothesis that these lectins inhibit through different and complex modes of action. Our findings provide important insights into the mechanisms by which lectins inhibit HCV infection. Overall, the data suggest MVL and CV-N have the potential for toxicity due to interactions with cellular proteins while GNA may be a better therapeutic agent due to specificity for the HCV gpE1E2.
authors.affiliation: Laboratory of Hepatitis Viruses, Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892 USA.
authors.forename: Alla
authors.initials: A
authors.lastname: Kachko
authors.affiliation: Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda Maryland 20892, USA.
authors.forename: Sandra
authors.initials: S
authors.lastname: Loesgen
authors.affiliation: Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda Maryland 20892, USA.|Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda Maryland 20892, USA.
authors.forename: Syed
authors.initials: S
authors.lastname: Shahzad-Ul-Hussan
authors.affiliation: Laboratory of Hepatitis Viruses, Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892 USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Tan
authors.affiliation: Laboratory of Hepatitis Viruses, Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892 USA.
authors.forename: Iryna
authors.initials: I
authors.lastname: Zubkova
authors.affiliation: Microscopy and Imaging Core Facility, Center for Biologics Evaluation and Research, US Food and Drug Administration, Bethesda, MD 20892. USA.
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Laboratory of Hepatitis Viruses, Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892 USA.
authors.forename: Frances
authors.initials: F
authors.lastname: Wells
authors.affiliation: Laboratory of Method Development, Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892. USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Rubin
authors.affiliation: Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda Maryland 20892, USA.
authors.forename: Carole A
authors.initials: CA
authors.lastname: Bewley
authors.affiliation: Laboratory of Hepatitis Viruses, Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892 USA.
authors.forename: Marian E
authors.initials: ME
authors.lastname: Major
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000494:pharmacology*; D002352:Carrier Proteins / Q000494:pharmacology*; D045744:Cell Line, Tumor; D000458:Cyanobacteria / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D016174:Hepacivirus / Q000187:drug effects*; D006801:Humans; D037241:Mannose-Binding Lectins / Q000494:pharmacology*; D046931:Microcystis / Q000378:metabolism*; D037121:Plant Lectins / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D000998:Antiviral Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D006023:Glycoproteins; D037241:Mannose-Binding Lectins; D037121:Plant Lectins; D011994:Recombinant Proteins; C063117:snowdrop lectin; C107733:cyanovirin N