title: Engineered serine protease inhibitor prevents furin-catalyzed activation of the fusion glycoprotein and production of infectious measles virus.
abstract: We have identified the major cellular endoprotease that activates the fusion (F) glycoprotein of measles virus (MV) and have engineered a serine protease inhibitor (serpin) to target the endoprotease and inhibit the production of infectious MV. The F-protein precursor of MV was not cleaved efficiently into the mature F protein in human colon carcinoma cells lacking functional furin, indicating that furin is the major enzyme responsible for activation of the MV F protein. A human serpin alpha 1-antitrypsin variant was engineered to specifically inhibit furin. When expressed from a recombinant vaccinia virus in primate cells infected by MV, the engineered serpin (alpha 1-PDX) specifically inhibited furin-catalyzed cleavage of the F-protein precursor without affecting synthesis of other MV proteins. We generated human glioma cells stably expressing alpha 1-PDX. MV infection in these cells did not result in syncytia. The infected cells produced all the MV proteins, but the F-protein precursor remained largely uncleaved. This did not prevent virus assembly. However, the released virions contained inactive F-protein precursor rather than mature F protein, and infectious-virus titers were reduced by 3 to 4 orders of magnitude. These results show that a mature F protein is not required for the assembly of MV but is crucial for virus infectivity. The engineered serpin may offer a novel molecular antiviral approach against MV.
authors.affiliation: Department of Microbiology, University of Washington School of Medicine, Seattle 98195, USA.
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: A
authors.initials: A
authors.lastname: Hirano
authors.forename: S
authors.initials: S
authors.lastname: Stenglein
authors.forename: J
authors.initials: J
authors.lastname: Nelson
authors.forename: G
authors.initials: G
authors.lastname: Thomas
authors.forename: T C
authors.initials: TC
authors.lastname: Wong
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D002460:Cell Line; D003588:Cytopathogenic Effect, Viral / Q000187:drug effects; D045683:Furin; D006367:HeLa Cells; D006801:Humans; D008459:Measles virus / Q000187:drug effects* / Q000254:growth & development / Q000472:pathogenicity; D015202:Protein Engineering; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D015843:Serpins / Q000235:genetics / Q000494:pharmacology*; D013381:Subtilisins / Q000378:metabolism*; D014760:Viral Fusion Proteins / Q000378:metabolism*; D014774:Virulence / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D015843:Serpins; D014760:Viral Fusion Proteins; D013381:Subtilisins; D045683:Furin