Identification of Residues in the Human Respiratory Syncytial Virus Fusion Protein That Modulate Fusion Activity and Pathogenesis

• Type of Material: Article
• Authors: Anne L. Hotard, Emory University; Sujin Lee, Emory University; Michael G. Currier, Emory University; James E. Crew. Jr., Vanderbilt Medical Center; Kaori Sakamoto, University of Georgia; Dawn C. Newcomb, Vanderbilt University School of Medicine; R.Stokes Peebles.Jr., Vanderbilt University School of Medicine; Richard Plemper, Emory University; Martin Moore, Emory University
• Language: English
• Date: 2015-01-01
• Publisher: American Society for Microbiology
• Publication Version: Final Published Version
• Copyright Statement: © 2015, American Society for Microbiology
• License: Creative Commons Attribution-Noncommercial 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1128/JVI.02472-14
• Title of Journal or Parent Work: Journal of Virology
• ISSN: 0022-538X
• Volume: 89
• Issue: 1
• Start Page: 512
• End Page: 522
• Grant/Funding Information: This work was supported by NIH grants 1R01AI087798 (to M.L.M.) and 1U19AI095227 (to R.S.P.), the Children's Center for Immunology and Vaccines, and public health service grant AI083402 from the NIH/NIAID (to R.K.P.)
• Research Categories: Biology, Virology; Health Sciences, General

Abstract

Human respiratory syncytial virus (RSV) lower respiratory tract infection can result in inflammation and mucus plugging of airways. RSV strain A2-line19F induces relatively high viral load and mucus in mice. The line 19 fusion (F) protein harbors five unique residues compared to the non-mucus-inducing strains A2 and Long, at positions 79, 191, 357, 371, and 557. We hypothesized that differential fusion activity is a determinant of pathogenesis. In a cell-cell fusion assay, line 19 F was more fusogenic than Long F. We changed the residues unique to line 19 F to the corresponding residues in Long F and identified residues 79 and 191 together as responsible for high fusion activity. Surprisingly, mutation of residues 357 or 357 with 371 resulted in gain of fusion activity. Thus, we generated RSV F mutants with a range of defined fusion activity and engineered these into recombinant viruses. We found a clear, positive correlation between fusion activity and early viral load in mice; however, we did not detect a correlation between viral loads and levels of airway mucin expression. The F mutant with the highest fusion activity, A2-line19FK357T/ Y371N, induced high viral loads, severe lung histopathology, and weight loss but did not induce high levels of airway mucin expression. We defined residues 79/191 as critical for line 19 F fusion activity and 357/371 as playing a role in A2-line19F mucus induction. Defining the molecular basis of the role of RSV F in pathogenesis may aid vaccine and therapeutic strategies aimed at this protein.