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Am J Physiol Lung Cell Mol Physiol. 2015 Feb 1;308(3):L270-86. doi: 10.1152/ajplung.00011.2014. Epub 2014 Oct 31.

Suppression of influenza A virus replication in human lung epithelial cells by noncytotoxic concentrations bafilomycin A1.

Author information

1
Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada; Biology of Breathing Group, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada;
2
Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada; Biology of Breathing Group, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada; Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada;
3
Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Surgery, University of Manitoba, Winnipeg, Manitoba, Canada; and.
4
Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada;
5
Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada; Biology of Breathing Group, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada; Department of Internal Medicine, University of Manitoba, Winnipeg, Manitoba, Canada andrew.halayko@umanitoba.ca.

Abstract

Subcellular trafficking within host cells plays a critical role in viral life cycles, including influenza A virus (IAV). Thus targeting relevant subcellular compartments holds promise for effective intervention to control the impact of influenza infection. Bafilomycin A1 (Baf-A1), when used at relative high concentrations (≥10 nM), inhibits vacuolar ATPase (V-ATPase) and reduces endosome acidification and lysosome number, thus inhibiting IAV replication but promoting host cell cytotoxicity. We tested the hypothesis that much lower doses of Baf-A1 also have anti-IAV activity, but without toxic effects. Thus we assessed the antiviral activity of Baf-A1 at different concentrations (0.1-100 nM) in human alveolar epithelial cells (A549) infected with IAV strain A/PR/8/34 virus (H1N1). Infected and mock-infected cells pre- and cotreated with Baf-A1 were harvested 0-24 h postinfection and analyzed by immunoblotting, immunofluorescence, and confocal and electron microscopy. We found that Baf-A1 had disparate concentration-dependent effects on subcellular organelles and suppressed affected IAV replication. At concentrations ≥10 nM Baf-A1 inhibited acid lysosome formation, which resulted in greatly reduced IAV replication and release. Notably, at a very low concentration of 0.1 nM that is insufficient to reduce lysosome number, Baf-A1 retained the capacity to significantly impair IAV nuclear accumulation as well as IAV replication and release. In contrast to the effects of high concentrations of Baf-A1, very low concentrations did not exhibit cytotoxic effects or induce apoptotic cell death, based on morphological and FACS analyses. In conclusion, our results reveal that low-concentration Baf-A1 is an effective inhibitor of IAV replication, without impacting host cell viability.

KEYWORDS:

apoptotic cell death; autophagy; influenza A virus; low-dose bafilomycin A1; noncytotoxic

PMID:
25361566
PMCID:
PMC4338931
DOI:
10.1152/ajplung.00011.2014
[Indexed for MEDLINE]
Free PMC Article

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