The K186E amino acid substitution in the canine influenza virus H3N8 NS1 protein restores its ability to inhibit host gene expression

Nogales, A., Chauché, C. , DeDiego, M. L., Topham, D. J., Parrish, C. R., Murcia, P. R. and Martínez-Sobrido, L. (2017) The K186E amino acid substitution in the canine influenza virus H3N8 NS1 protein restores its ability to inhibit host gene expression. Journal of Virology, 91(22), e00877-17. (doi:10.1128/JVI.00877-17) (PMID:28835506)

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Abstract

Canine influenza viruses (CIVs) are the causative agents of canine influenza, a contagious respiratory disease in dogs, and include the equine-origin H3N8 and the avian-origin H3N2. Influenza A virus (IAV) non-structural protein 1 (NS1) is a virulence factor essential for counteracting the innate immune response. Here, we evaluated the ability of H3N8 CIV NS1 to inhibit host innate immune responses. We found that H3N8 CIV NS1 was able to efficiently counteract interferon (IFN) responses but was unable to block general gene expression in human or canine cells. Such ability was restored by a single amino acid substitution in position 186 (K186E) that resulted in NS1 binding to the 30-kDa subunit of the cleavage and polyadenylation specificity factor (CPSF30), a cellular protein involved in pre-mRNA processing. We also examined the frequency distribution of K186 and E186 among H3N8 CIVs and equine influenza viruses (EIVs), the ancestors of H3N8 CIV, and experimentally determined the impact of amino acid 186 in the ability of different CIV and EIV NS1s to inhibit general gene expression. In all cases, the presence of E186 was responsible for the control of host gene expression. Contrastingly, the NS1 protein of H3N2 CIV harbors E186 and blocks general gene expression in canine cells. Altogether, our results confirm previous studies on the strain-dependent ability of NS1 to block general gene expression. Moreover, the observed polymorphism on amino acid 186 between H3N8 and H3N2 CIVs might be the result of adaptive changes acquired during long-term circulation of avian-origin IAVs in mammals. IMPORTANCE: Canine influenza is a respiratory disease of dogs caused by two CIV subtypes, the H3N8 and H3N2 viruses of equine and avian origin, respectively. Influenza NS1 is the main viral factor responsible for the control of host innate immune responses and changes in NS1 can play an important role in host adaptation. Here we assessed the ability of H3N8 CIV NS1 to inhibit host innate immune responses and gene expression. The H3N8 CIV NS1 did not block host gene expression but this activity was restored by a single amino acid substitution (K186E), which was responsible for NS1 binding to the host factor CPSF30. In contrast, the H3N2 CIV NS1, that contains E186, blocks general gene expression. Our results suggest that the ability to block host gene expression is not required for influenza replication in mammals but might be important in the long-term adaptation of avian-origin influenza viruses to mammals.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Parrish, Colin and Chauche, Dr Caroline and Murcia, Dr Pablo
Authors: Nogales, A., Chauché, C., DeDiego, M. L., Topham, D. J., Parrish, C. R., Murcia, P. R., and Martínez-Sobrido, L.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Journal of Virology
Publisher:American Society for Microbiology
ISSN:0022-538X
ISSN (Online):1098-5514
Published Online:23 August 2017
Copyright Holders:Copyright © 2017 American Society for Microbiology
First Published:First published in Journal of Virology 91(22):e00877-17
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
709011Quinquennial Core FundsMassimo PalmariniMedical Research Council (MRC)MC_UU_12014/9MVLS III - CENTRE FOR VIRUS RESEARCH