The Respiratory Syncytial Virus Fusion Protein Targets to the Perimeter of Inclusion Bodies and Facilitates Filament Formation by a Cytoplasmic Tail-Dependent Mechanism

• Type of Material: Article
• Authors: Pradyumna S. Baviskar, Oklahoma State University; Anne L. Hotard, Emory University; Martin Moore, Emory University; Antonius G. P. Oomens, Oklahoma State University
• Language: English
• Date: 2013-10
• Publisher: American Society for Microbiology
• Publication Version: Final Published Version
• Copyright Statement: © 2013, American Society for Microbiology. All Rights Reserved.
• Final Published Version (URL): http://dx.doi.org/10.1128/JVI.03086-12
• Title of Journal or Parent Work: Journal of Virology
• ISSN: 0022-538X
• Volume: 87
• Issue: 19
• Start Page: 10730
• End Page: 10741
• Grant/Funding Information: A.G.P.O. was supported by an OHRS award for project number HR08-139S from the Oklahoma Center for the Advancement of Science and Technology.; M.L.M. was supported by NIH 1RO1AI087798; and NIH 1U19A1095227.
• Keywords: ENVELOPE PROTEIN; PARTICLES; INFECTED-CELLS; Science & Technology; GLYCOPROTEIN; DOMAIN; MATRIX PROTEIN; VIROLOGY; Life Sciences & Biomedicine; F-PROTEIN; IDENTIFICATION; POLARIZED EPITHELIAL-CELLS; NUCLEOPROTEIN; Virology
• Research Categories: Biology, Virology

Abstract

The human respiratory syncytial virus (HRSV) fusion (F) protein cytoplasmic tail (CT) and matrix (M) protein are key mediators of viral assembly, but the underlying mechanisms are poorly understood. A complementation assay was developed to systematically examine the role of the F protein CT in infectious virus production. The ability of F mutants with alanine substitutions in the CT to complement an F-null virus in generating infectious progeny was quantitated by flow cytometry. Two CT regions with impact on infectious progeny production were identified: residues 557 to 566 (CT-R1) and 569 to 572 (CT-R2). Substitutions in CT-R1 decreased infectivity by 40 to 85% and increased the level of F-induced cell-cell fusion but had little impact on assembly of viral surface filaments, which are believed to be virions. Substitutions in CT-R2, as well as deletion of the entire CT, abrogated infectious progeny production and impaired viral filament formation. However, CT-R2 mutations did not block but rather delayed the formation of viral filaments, which continued to form at a low rate and contained the viralMprotein and nucleoprotein (N). Microscopy analysis revealed that substitutions in CT-R2 but not CT-R1 led to accumulation ofMand F proteins within and at the perimeter of viral inclusion bodies (IBs), respectively. The accumulation ofMand F at IBs and coincident strong decrease in filament formation and infectivity upon CT-R2 mutations suggest that F interaction with IBs is an important step in the virion assembly process and that CT residues 569 to 572 act to facilitate release of M-ribonucleoprotein complexes from IBs.