title: Peptide inhibitors of dengue-virus entry target a late-stage fusion intermediate.
abstract: The mechanism of membrane fusion by "class II" viral fusion proteins follows a pathway that involves large-scale domain rearrangements of the envelope glycoprotein (E) and a transition from dimers to trimers. The rearrangement is believed to proceed by an outward rotation of the E ectodomain after loss of the dimer interface, followed by a reassociation into extended trimers. The approximately 55-aa-residue, membrane proximal "stem" can then zip up along domain II, bringing together the transmembrane segments of the C-terminus and the fusion loops at the tip of domain II. We find that peptides derived from the stem of dengue-virus E bind stem-less E trimer, which models a conformational intermediate. In vitro assays demonstrate that these peptides specifically block viral fusion. The peptides inhibit infectivity with potency proportional to their affinity for the conformational intermediate, even when free peptide is removed from a preincubated inoculum before infecting cells. We conclude that peptides bind virions before attachment and are carried with virions into endosomes, the compartment in which acidification initiates fusion. Binding depends on particle dynamics, as there is no inhibition of infectivity if preincubation and separation are at 4 degrees C rather than 37 degrees C. We propose a two-step model for the mechanism of fusion inhibition. Targeting a viral entry pathway can be an effective way to block infection. Our data, which support and extend proposed mechanisms for how the E conformational change promotes membrane fusion, suggest strategies for inhibiting flavivirus entry.
authors.affiliation: Jack and Eileen Connors Laboratory of Structural Biology, Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Aaron G
authors.initials: AG
authors.lastname: Schmidt
authors.forename: Priscilla L
authors.initials: PL
authors.lastname: Yang
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Harrison
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000378:metabolism / Q000494:pharmacology*; D003716:Dengue Virus / Q000737:chemistry / Q000378:metabolism / Q000472:pathogenicity*; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology*; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000378:metabolism*; D014771:Virion / Q000187:drug effects; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D010455:Peptides; D014759:Viral Envelope Proteins; C072281:E protein TH Sman, Dengue virus
references.citation: Chem Phys Lipids. 2002 Jun;116(1-2):57-74
references.pmid: 12093535
references.citation: J Virol. 2007 Nov;81(21):12019-28
references.pmid: 17728239
references.citation: Proc Natl Acad Sci U S A. 1992 Nov 1;89(21):10537-41
references.pmid: 1438243
references.citation: EMBO J. 1993 Feb;12(2):693-701
references.pmid: 8440260
references.citation: Proc Natl Acad Sci U S A. 2003 Jun 10;100(12):6986-91
references.pmid: 12759475
references.citation: Structure. 2004 Sep;12(9):1607-18
references.pmid: 15341726
references.citation: J Virol. 2002 Apr;76(8):3784-90
references.pmid: 11907218
references.citation: Expert Rev Mol Med. 2008 May 12;10:e12
references.pmid: 18471342
references.citation: Am J Trop Med Hyg. 1982 Jul;31(4):830-6
references.pmid: 6285749
references.citation: PLoS Pathog. 2008 Dec;4(12):e1000244
references.pmid: 19096510
references.citation: Science. 2003 Oct 10;302(5643):248
references.pmid: 14551429
references.citation: EMBO J. 2004 Feb 25;23(4):728-38
references.pmid: 14963486
references.citation: Science. 2008 Mar 28;319(5871):1834-7
references.pmid: 18369148
references.citation: Science. 2008 Mar 28;319(5871):1830-4
references.pmid: 18369147
references.citation: Cell Host Microbe. 2007 Apr 19;1(2):135-45
references.pmid: 18005691
references.citation: PLoS Pathog. 2009 May;5(5):e1000453
references.pmid: 19478866
references.citation: Nat Struct Biol. 2003 Nov;10(11):907-12
references.pmid: 14528291
references.citation: Virology. 1997 Nov 10;238(1):14-21
references.pmid: 9375004
references.citation: J Virol. 1991 Oct;65(10):5579-83
references.pmid: 1716695
references.citation: Virol J. 2005 Jun 01;2:49
references.pmid: 15927084
references.citation: J Virol. 2006 Nov;80(22):11000-8
references.pmid: 16943291
references.citation: Nat Med. 1998 Nov;4(11):1302-7
references.pmid: 9809555
references.citation: Antiviral Res. 2009 Dec;84(3):260-6
references.pmid: 19800368
references.citation: Nat Struct Mol Biol. 2008 Jul;15(7):690-8
references.pmid: 18596815
references.citation: Nat Struct Mol Biol. 2008 Mar;15(3):312-7
references.pmid: 18264114
references.citation: J Gen Virol. 1992 Nov;73 ( Pt 11):2999-3003
references.pmid: 1279106
references.citation: J Cell Biol. 2008 Oct 20;183(2):353-61
references.pmid: 18936253
references.citation: Cell. 1998 May 29;93(5):681-4
references.pmid: 9630213
references.citation: Nature. 2004 Jan 22;427(6972):313-9
references.pmid: 14737159
references.citation: Proc Natl Acad Sci U S A. 1994 Dec 20;91(26):12676-80
references.pmid: 7809100
references.citation: J Cell Biol. 2005 Oct 10;171(1):111-20
references.pmid: 16216925
references.citation: Nature. 1995 May 25;375(6529):291-8
references.pmid: 7753193
references.citation: J Virol. 2001 May;75(9):4268-75
references.pmid: 11287576
references.citation: J Virol. 1995 Feb;69(2):695-700
references.pmid: 7529335