title: Redox regulation of the influenza hemagglutinin maturation process: a new cell-mediated strategy for anti-influenza therapy.
abstract: OBJECTIVE
  The aim of this study was to determine whether GSH-C4, a hydrophobic glutathione derivative, affects in vitro and in vivo influenza virus infection by interfering with redox-sensitive intracellular pathways involved in the maturation of viral hemagglutinin (HA).
  
  
  RESULTS
  GSH-C4 strongly inhibited influenza A virus replication in cultured cells and in lethally infected mice, where it also reduced lung damage and mortality. In cell-culture studies, GSH-C4 arrested viral HA folding; the disulfide-rich glycoprotein remained in the endoplasmic reticulum as a reduced monomer instead of undergoing oligomerization and cell plasma-membrane insertion. HA maturation depends on the host-cell oxidoreductase, protein disulfide isomerase (PDI), whose activity in infected cells is probably facilitated by virus-induced glutathione depletion. By correcting this deficit, GSH-C4 increased levels of reduced PDI and inhibited essential disulfide bond formation in HA. Host-cell glycoprotein expression in uninfected cells was unaffected by glutathione, which thus appears to act exclusively on glutathione-depleted cells.
  
  
  METHODS
  All currently approved anti-influenza drugs target essential viral structures, and their efficacy is limited by toxicity and by the almost inevitable selection of drug-resistant viral mutants. GSH-C4 inhibits influenza virus replication by modulating redox-sensitive pathways in infected cells, without producing toxicity in uninfected cells or animals. Novel anti-influenza drugs that target intracellular pathways essential for viral replication ("cell-based approach") offer two important potential advantages: they are more difficult for the virus to adapt to and their efficacy should not be dependent on virus type, strain, or antigenic properties.
  
  
  CONCLUSIONS
  Redox-sensitive host-cell pathways exploited for viral replication are promising targets for effective anti-influenza strategies.
authors.affiliation: San Raffaele Pisana Scientific Institute for Research, Hospitalization, and Health Care, Rome, Italy.
authors.forename: Rossella
authors.initials: R
authors.lastname: Sgarbanti
authors.forename: Lucia
authors.initials: L
authors.lastname: Nencioni
authors.forename: Donatella
authors.initials: D
authors.lastname: Amatore
authors.forename: Paolo
authors.initials: P
authors.lastname: Coluccio
authors.forename: Alessandra
authors.initials: A
authors.lastname: Fraternale
authors.forename: Patrizio
authors.initials: P
authors.lastname: Sale
authors.forename: Caterina L
authors.initials: CL
authors.lastname: Mammola
authors.forename: Guido
authors.initials: G
authors.lastname: Carpino
authors.forename: Eugenio
authors.initials: E
authors.lastname: Gaudio
authors.forename: Mauro
authors.initials: M
authors.lastname: Magnani
authors.forename: Maria R
authors.initials: MR
authors.lastname: Ciriolo
authors.forename: Enrico
authors.initials: E
authors.lastname: Garaci
authors.forename: Anna Teresa
authors.initials: AT
authors.lastname: Palamara
mesh_terms: D000818:Animals; D002460:Cell Line; D004195:Disease Models, Animal; D004220:Disulfides / Q000737:chemistry; D004285:Dogs; D005260:Female; D005978:Glutathione / Q000031:analogs & derivatives*; D006389:Hemagglutinins, Viral / Q000378:metabolism*; D009980:Influenza A virus / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000188:drug therapy* / Q000378:metabolism; D010084:Oxidation-Reduction; D019704:Protein Disulfide-Isomerases / Q000378:metabolism; D017510:Protein Folding / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects
chemical_list: D004220:Disulfides; D006389:Hemagglutinins, Viral; C562006:glutathione-C4; D019704:Protein Disulfide-Isomerases; D005978:Glutathione