RSV-encoded NS2 promotes epithelial cell shedding and distal airway obstruction
Rachael M. Liesman, … , Peter L. Collins, Raymond J. Pickles
Rachael M. Liesman, … , Peter L. Collins, Raymond J. Pickles
Published April 8, 2014
Citation Information: J Clin Invest. 2014;124(5):2219-2233. https://doi.org/10.1172/JCI72948.
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Research Article Virology

RSV-encoded NS2 promotes epithelial cell shedding and distal airway obstruction

Abstract

Respiratory syncytial virus (RSV) infection is the major cause of bronchiolitis in young children. The factors that contribute to the increased propensity of RSV-induced distal airway disease compared with other commonly encountered respiratory viruses remain unclear. Here, we identified the RSV-encoded nonstructural 2 (NS2) protein as a viral genetic determinant for initiating RSV-induced distal airway obstruction. Infection of human cartilaginous airway epithelium (HAE) and a hamster model of disease with recombinant respiratory viruses revealed that NS2 promotes shedding of infected epithelial cells, resulting in two consequences of virus infection. First, epithelial cell shedding accelerated the reduction of virus titers, presumably by clearing virus-infected cells from airway mucosa. Second, epithelial cells shedding into the narrow-diameter bronchiolar airway lumens resulted in rapid accumulation of detached, pleomorphic epithelial cells, leading to acute distal airway obstruction. Together, these data indicate that RSV infection of the airway epithelium, via the action of NS2, promotes epithelial cell shedding, which not only accelerates viral clearance but also contributes to acute obstruction of the distal airways. Our results identify RSV NS2 as a contributing factor for the enhanced propensity of RSV to cause severe airway disease in young children and suggest NS2 as a potential therapeutic target for reducing the severity of distal airway disease.

Authors

Rachael M. Liesman, Ursula J. Buchholz, Cindy L. Luongo, Lijuan Yang, Alan D. Proia, John P. DeVincenzo, Peter L. Collins, Raymond J. Pickles

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Figure 8

Distal airway obstruction and accelerated clearance of virus infection in hamsters infected by PIV3-NS2.

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Distal airway obstruction and accelerated clearance of virus infection i...
(A and B) Representative images of histologic cross sections of hamster large airways (A) and small airways (B) 3 days and 5 days after infection with PIV3 or PIV3-NS2. Note the rapid loss of PIV3-NS2–infected cells from airways at 5 days pi, a time when PIV3 infection remained robust. Scale bar: 100 μm. (C) Morphometric quantitative analysis of distal airway cell accumulation in hamsters infected with PIV3 or PIV3-NS2 by measuring the percentage of cross-sectional airway lumen surface area occupied by virus antigen–positive cells at day 3 pi. Histologic, antigen-stained whole lung sections from 6 animals were measured. Each column represents an individual animal, and each symbol represents occlusion of an individual airway. Statistical analysis of the mean occlusion values of the two groups was used to determine significance. P < 0.01, Mann-Whitney U test. (D) Whole lung virus loads in hamsters infected with PIV3 (black circles) or PIV3-NS2 (white squares) measured over time, demonstrating a more rapid clearance of PIV3 infection when the virus expressed RSV NS2. Data (mean ± SEM) represent 3 independent experiments with a total of 4 to 9 animals per time point. All viruses expressed GFP. ***P < 0.0001, unpaired t test.