Single-particle measurements of filamentous influenza virions reveal damage induced by freezing

Hirst, J. C. and Hutchinson, E. C. (2019) Single-particle measurements of filamentous influenza virions reveal damage induced by freezing. Journal of General Virology, 100(12), pp. 1631-1640. (doi: 10.1099/jgv.0.001330) (PMID:31553305) (PMCID:PMC6904231)

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Clinical isolates of influenza virus produce pleiomorphic virions, ranging from small spheres to elongated filaments. The filaments are seemingly adaptive in natural infections, but their basic functional properties are poorly understood and functional studies of filaments often report contradictory results. This may be due to artefactual damage from routine laboratory handling, an issue which has been noted several times without being explored in detail. To determine whether standard laboratory techniques could damage filaments, we used immunofluorescence microscopy to rapidly and reproducibly quantify and characterize the dimensions of filaments. Most of the techniques we tested had minimal impact on filaments, but freezing to −70 °C, a standard storage step before carrying out functional studies on influenza viruses, severely reduced their concentration, median length and the infectivity of the whole virion population. We noted that damage from freezing is likely to have affected most of the functional studies of filaments performed to date, and to address this we show that it can be mitigated by snap-freezing or incorporating the cryoprotectant DMSO. We recommend that functional studies of filaments characterize virion populations prior to analysis to ensure reproducibility, and that they use unfrozen samples if possible and cryoprotectants if not. These basic measures will support the robust functional characterizations of filaments that are required to understand their roles in natural influenza virus infections.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Hirst, Jack and Hutchinson, Dr Edward
Authors: Hirst, J. C., and Hutchinson, E. C.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Journal of General Virology
Publisher:Society for General Microbiology
ISSN (Online):1465-2099
Published Online:26 September 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:Journal of General Virology 100(12): 1631-1640
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
703851Functional investigations of the influenza virus proteomeEdward HutchinsonMedical Research Council (MRC)MR/N008618/1MVLS III - CENTRE FOR VIRUS RESEARCH
709011Quinquennial Core FundsMassimo PalmariniMedical Research Council (MRC)MC_UU_12014/9MVLS III - CENTRE FOR VIRUS RESEARCH