The K186E Amino Acid Substitution in the Canine Influenza Virus H3N8 NS1 Protein Restores Its Ability To Inhibit Host Gene Expression

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 viruses. Influenza A virus (IAV) nonstructural 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. In contrast, 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 origins, 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, which contains E186, blocks general gene expression. Our results suggest that the ability to block host gene expression is not required for influenza virus replication in mammals but might be important in the long-term adaptation of avian-origin influenza viruses to mammals.

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Identification of amino acid residues required for inhibition of host gene expression by influenza A/Viet Nam/1203/2004 H5N1 PA-X

Journal of Virology ◽

10.1128/jvi.00408-21 ◽

2021 ◽

Cited By ~ 1

Author(s):

Kevin Chiem ◽

Darío López-García ◽

Javier Ortego ◽

Luis Martinez-Sobrido ◽

Marta L. DeDiego ◽

...

Keyword(s):

Gene Expression ◽

Amino Acid ◽

Influenza A ◽

Influenza Viruses ◽

Host Gene ◽

Viet Nam ◽

Amino Acid Residues ◽

Host Gene Expression ◽

X Protein ◽

Identify Amino Acid

PA-X is a non-structural protein of influenza A virus (IAV), which is encoded by the polymerase acidic (PA) N-terminal region that contains a C-terminal +1 frameshifted sequence. IAV PA-X protein modulates virus-induced host innate immune responses and viral pathogenicity via suppression of host gene expression or cellular shutoff, through cellular mRNA cleavage. Highly pathogenic avian influenza viruses (HPAIV) of the H5N1 subtype naturally infect different avian species, they have an enormous economic impact in the poultry farming, and they also have zoonotic and pandemic potential, representing a risk to human public health. In the present study, we describe a novel bacteria-based approach to identify amino acid residues in the PA-X protein of the HPAIV A/Viet Nam/1203/2004 H5N1 that are important for its ability to inhibit host protein expression or cellular shutoff activity. Identified PA-X mutants displayed a reduced shutoff activity as compared to that of the wild-type (WT) A/Viet Nam/1203/2004 H5N1 PA-X protein. Notably, this new bacteria-based screening allowed us to identify amino acid residues widely distributed over the entire N-terminal region of PA-X. Furthermore, we found that some of the residues affecting A/Viet Nam/1203/2004 H5N1 PA-X host shutoff activity also affect PA polymerase activity in a minigenome assay. This information could be used for the rational design of new and more effective compounds with antiviral activity against IAV. Moreover, our results demonstrate the feasibility of using this bacteria-based approach to identify amino acid residues important for the activity of viral proteins to inhibit host gene expression. IMPORTANCE Highly pathogenic avian influenza viruses (HPAIV) continue to pose a huge threat to global animal and human health. Despite of the limited genome size of Influenza A virus (IAV), the virus encodes eight main viral structural proteins and multiple accessory non-structural proteins, depending on the IAV type, subtype or strain. One of the IAV accessory proteins, PA-X, is encoded by the polymerase acidic (PA) protein and is involved in pathogenicity through the modulation of IAV-induced host inflammatory and innate immune responses. However, the molecular mechanism(s) of IAV PA-X regulation of the host immune response is not well understood. In this work, we used, for the first time, a bacteria-based approach for the identification of amino acids important for the ability of IAV PA-X to induce host shutoff activity and describe novel residues relevant for its ability to inhibit host gene expression, and their contribution in PA polymerase activity.

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Functional Evolution of the 2009 Pandemic H1N1 Influenza Virus NS1 and PA in Humans

Journal of Virology ◽

10.1128/jvi.01206-18 ◽

2018 ◽

Vol 92 (19) ◽

Cited By ~ 9

Author(s):

Aitor Nogales ◽

Luis Martinez-Sobrido ◽

Kevin Chiem ◽

David J. Topham ◽

Marta L. DeDiego

Keyword(s):

Gene Expression ◽

Influenza Virus ◽

Amino Acid ◽

H1n1 Influenza ◽

Innate Immune ◽

Host Gene ◽

Pandemic H1n1 ◽

Host Gene Expression ◽

Pandemic H1n1 Influenza ◽

Nonstructural Protein 1

ABSTRACT In 2009, a pandemic H1N1 influenza A virus (IAV) (pH1N1) emerged in the human population from swine causing a pandemic. Importantly, this virus is still circulating in humans seasonally. To analyze the evolution of pH1N1 in humans, we sequenced viral genes encoding proteins inhibiting general gene expression (nonstructural protein 1 [NS1] and PA-X) from circulating seasonal viruses and compared them to the viruses isolated at the origin of the pandemic. Recent pH1N1 viruses contain amino acid changes in the NS1 protein (E55K, L90I, I123V, E125D, K131E, and N205S), as previously described (A. M. Clark, A. Nogales, L. Martinez-Sobrido, D. J. Topham, and M. L. DeDiego, J Virol 91:e00721-17, 2017, https://doi.org/10.1128/JVI.00721-17), and amino acid changes in the PA-X protein (V100I, N204S, R221Q, and L229S). These amino acid differences between early and more recent pH1N1 isolates are responsible for increased NS1-mediated inhibition of host gene expression and decreased PA-X-mediated shutoff, including innate immune response genes. In addition, currently circulating pH1N1 viruses have acquired amino acid changes in the PA protein (V100I, P224S, N321K, I330V, and R362K). A recombinant pH1N1 virus containing PA, PA-X, and NS1 genes from currently circulating viruses is fitter in replication in cultured cells and in mice and is slightly more pathogenic than the original ancestor pH1N1 virus. These results demonstrate the need to monitor the evolution of pH1N1 in humans for mutations in the viral genome that could result in enhanced virulence. Importantly, these results further support our previous findings suggesting that inhibition of global gene expression mediated by NS1 and PA-X proteins is subject to a balance which can determine virus pathogenesis and fitness. IMPORTANCE IAVs emerge in humans from animal reservoirs, causing unpredictable pandemics. One of these pandemics was caused by an H1N1 virus in 2009, and this virus is still circulating seasonally. To analyze host-virus adaptations likely affecting influenza virus pathogenesis, protein amino acid sequences from viruses circulating at the beginning of the pandemic and those circulating currently were compared. Currently circulating viruses have incorporated amino acid changes in two viral proteins (NS1 and PA-X), affecting innate immune responses, and in the PA gene. These amino acid differences led to increased NS1-mediated and decreased PA-X-mediated inhibition of host gene expression. A recombinant pH1N1 virus containing PA, PA-X, and NS1 genes from recently circulating viruses is fitter in replication in tissue culture cells and in mice, and the virus is more pathogenic in vivo. Importantly, these results suggest that a balance in the abilities of NS1 and PA-X to induce host shutoff is beneficial for IAVs.

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Critical Role of Plasmacytoid Dendritic Cells in Regulating Gene Expression and Innate Immune Responses to Human Rhinovirus-16

Frontiers in Immunology ◽

10.3389/fimmu.2017.01351 ◽

2017 ◽

Vol 8 ◽

Cited By ~ 6

Author(s):

Yang Xi ◽

Niamh M. Troy ◽

Denise Anderson ◽

Olga M. Pena ◽

Jason P. Lynch ◽

...

Keyword(s):

Gene Expression ◽

Dendritic Cells ◽

Immune Responses ◽

Critical Role ◽

Plasmacytoid Dendritic Cells ◽

Innate Immune ◽

Human Rhinovirus ◽

Innate Immune Responses

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Influenza virus N-linked glycosylation and innate immunity

Bioscience Reports ◽

10.1042/bsr20171505 ◽

2019 ◽

Vol 39 (1) ◽

Cited By ~ 14

Author(s):

Ian A. York ◽

James Stevens ◽

Irina V. Alymova

Keyword(s):

Immune Responses ◽

Evolutionary Dynamics ◽

Analytical Techniques ◽

Influenza Viruses ◽

Innate Immune ◽

Global Public Health ◽

Innate Immune Responses ◽

Critical Determinant ◽

Public Health Challenge ◽

Seasonal Epidemics

AbstractInfluenza viruses cause seasonal epidemics and sporadic pandemics in humans. The virus’s ability to change its antigenic nature through mutation and recombination, and the difficulty in developing highly effective universal vaccines against it, make it a serious global public health challenge. Influenza virus’s surface glycoproteins, hemagglutinin and neuraminidase, are all modified by the host cell’s N-linked glycosylation pathways. Host innate immune responses are the first line of defense against infection, and glycosylation of these major antigens plays an important role in the generation of host innate responses toward the virus. Here, we review the principal findings in the analytical techniques used to study influenza N-linked glycosylation, the evolutionary dynamics of N-linked glycosylation in seasonal versus pandemic and zoonotic strains, its role in host innate immune responses, and the prospects for lectin-based therapies. As the efficiency of innate immune responses is a critical determinant of disease severity and adaptive immunity, the study of influenza glycobiology is of clinical as well as research interest.

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Integrative Transcriptomics Reveals Activation of Innate Immune Responses and Inhibition of Inflammation During Oral Immunotherapy for Egg Allergy in Children

Frontiers in Immunology ◽

10.3389/fimmu.2021.704633 ◽

2021 ◽

Vol 12 ◽

Author(s):

Piia Karisola ◽

Kati Palosuo ◽

Victoria Hinkkanen ◽

Lukas Wisgrill ◽

Terhi Savinko ◽

...

Keyword(s):

Gene Expression ◽

Clinical Outcome ◽

Immune Responses ◽

Molecular Mechanisms ◽

Expression Patterns ◽

Oral Immunotherapy ◽

Innate Immune ◽

Egg Allergy ◽

Innate Immune Responses ◽

Open Label

We previously reported the results of a randomized, open-label trial of egg oral immunotherapy (OIT) in 50 children where 44% were desensitized and 46% were partially desensitized after 8 months of treatment. Here we focus on cell-mediated molecular mechanisms driving desensitization during egg OIT. We sought to determine whether changes in genome-wide gene expression in blood cells during egg OIT correlate with humoral responses and the clinical outcome. The blood cell transcriptome of 50 children receiving egg OIT was profiled using peripheral blood mononuclear cell (PBMC) samples obtained at baseline and after 3 and 8 months of OIT. We identified 467 differentially expressed genes (DEGs) after 3 or 8 months of egg OIT. At 8 months, 86% of the DEGs were downregulated and played a role in the signaling of TREM1, IL-6, and IL-17. In correlation analyses, Gal d 1–4-specific IgG4 antibodies associated positively with DEGs playing a role in pathogen recognition and antigen presentation and negatively with DEGs playing a role in the signaling of IL-10, IL-6, and IL-17. Desensitized and partially desensitized patients had differences in their antibody responses, and although most of the transcriptomic changes were shared, both groups had also specific patterns, which suggest slower changes in partially desensitized and activation of NK cells in the desensitized group. OIT for egg allergy in children inhibits inflammation and activates innate immune responses regardless of the clinical outcome at 8 months. Changes in gene expression patterns first appear as posttranslational protein modifications, followed by more sustained epigenetic gene regulatory functions related to successful desensitization.

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Stereotyped and specific gene expression programs in human innate immune responses to bacteria

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.231625398 ◽

2002 ◽

Vol 99 (2) ◽

pp. 972-977 ◽

Cited By ~ 285

Author(s):

J. C. Boldrick ◽

A. A. Alizadeh ◽

M. Diehn ◽

S. Dudoit ◽

C. L. Liu ◽

...

Keyword(s):

Gene Expression ◽

Immune Responses ◽

Innate Immune ◽

Specific Gene ◽

Innate Immune Responses ◽

Specific Gene Expression

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Profiles of Local and Systemic Inflammation in the Outcome of Treatment of Human Cutaneous Leishmaniasis Caused by Leishmania (Viannia)

Infection and Immunity ◽

10.1128/iai.00764-19 ◽

2019 ◽

Vol 88 (3) ◽

Cited By ~ 1

Author(s):

Adriana Navas ◽

Olga Fernández ◽

Carolina Gallego-Marín ◽

María del Mar Castro ◽

Mariana Rosales-Chilama ◽

...

Keyword(s):

Gene Expression ◽

Immune Responses ◽

Treatment Failure ◽

Cutaneous Leishmaniasis ◽

Expression Profiles ◽

Gene Expression Profiles ◽

Neutrophil Activation ◽

Innate Immune ◽

Innate Immune Responses ◽

Biopsy Specimens

ABSTRACT The immune mechanisms that contribute to the efficacy of treatment of cutaneous leishmaniasis (CL) are not fully understood. The aim of this study was to define immune correlates of the outcome of treatment of CL caused by Leishmania (Viannia) species during standard of care treatment with pentavalent antimonials. We conducted a comparative expression profiling of immune response genes in peripheral blood mononuclear cells (PBMCs) and lesion biopsy specimens obtained from CL patients before and at the end of treatment (EoT) with meglumine antimoniate. The ex vivo response of PBMCs to L. (V.) panamensis partially reflected that of lesion microenvironments. Significant downregulation of gene expression profiles consistent with local innate immune responses (monocyte and neutrophil activation and chemoattractant molecules) was observed at EoT in biopsy specimens of patients who cured (n = 8), compared to those from patients with treatment failure (n = 8). Among differentially expressed genes, pretreatment expression of CCL2 was significantly predictive of the therapeutic response (receiver operating characteristic [ROC] curve, area under the curve [AUC] = 0.82, P = 0.02). Polymorphisms in regulatory regions of the CCL2 promoter were analyzed in a pilot cohort of DNA samples from CL patients (cures, n = 20, and treatment failure, n = 20), showing putative association of polymorphisms rs13900(C/T) and rs2857656(G/C) with treatment outcome. Our data indicate that dampening gene expression profiles of monocyte and neutrophil activation characterize clinical cure after treatment of CL, supporting participation of parasite-sustained inflammation or deregulated innate immune responses in treatment failure.

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Innate Immune Responses of Skin Mucosa in Common Carp (Cyprinus Carpio) Fed a Diet Supplemented with Galactooligosaccharides

Animals ◽

10.3390/ani10030438 ◽

2020 ◽

Vol 10 (3) ◽

pp. 438 ◽

Cited By ~ 3

Author(s):

Elzbieta Pietrzak ◽

Jan Mazurkiewicz ◽

Anna Slawinska

Keyword(s):

Gene Expression ◽

Immune Responses ◽

Common Carp ◽

Geometric Mean ◽

Juvenile Fish ◽

Innate Immune ◽

Innate Immune Responses ◽

Immune Related Genes ◽

The Impact ◽

Skin Mucosa

Galactooligosaccharides (GOS) are well-known immunomodulatory prebiotics. We hypothesize that GOS supplemented in feed modulates innate immune responses in the skin-associated lymphoid tissue (SALT) of common carp. The aim of this study was to determine the impact of GOS on mRNA expression of the immune-related genes in skin mucosa. During the feeding trial, the juvenile fish (bodyweight 180 ± 5 g) were fed two types of diet for 50 days: control and supplemented with 2% GOS. At the end of the trial, a subset of fish was euthanized (n = 8). Skin mucosa was collected, and RNA was extracted. Gene expression analysis was performed with RT-qPCR to determine the mRNA abundance of the genes associated with innate immune responses in SALT, i.e., acute-phase protein (CRP), antimicrobial proteins (His2Av and GGGT5L), cytokines (IL1β, IL4, IL8, IL10, and IFNγ), lectin (CLEC4M), lyzosymes (LyzC and LyzG), mucin (M5ACL), peroxidase (MPO), proteases (CTSB and CTSD), and oxidoreductase (TXNL). The geometric mean of 40s s11 and ACTB was used to normalize the data. Relative quantification of the gene expression was calculated with ∆∆Ct. GOS upregulated INFγ (p ≤ 0.05) and LyzG (p ≤ 0.05), and downregulated CRP (p ≤ 0.01). We conclude that GOS modulates innate immune responses in the skin mucosa of common carp.

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Functional Evolution of Influenza Virus NS1 Protein in Currently Circulating Human 2009 Pandemic H1N1 Viruses

Journal of Virology ◽

10.1128/jvi.00721-17 ◽

2017 ◽

Vol 91 (17) ◽

Cited By ~ 20

Author(s):

Amelia M. Clark ◽

Aitor Nogales ◽

Luis Martinez-Sobrido ◽

David J. Topham ◽

Marta L. DeDiego

Keyword(s):

Gene Expression ◽

Influenza Virus ◽

Amino Acid ◽

Proinflammatory Cytokines ◽

Influenza A ◽

Host Gene ◽

Pandemic H1n1 ◽

Ns1 Protein ◽

Host Gene Expression ◽

Mouse Lungs

ABSTRACT In 2009, a novel H1N1 influenza virus emerged in humans, causing a global pandemic. It was previously shown that the NS1 protein from this human 2009 pandemic H1N1 (pH1N1) virus was an effective interferon (IFN) antagonist but could not inhibit general host gene expression, unlike other NS1 proteins from seasonal human H1N1 and H3N2 viruses. Here we show that the NS1 protein from currently circulating pH1N1 viruses has evolved to encode 6 amino acid changes (E55K, L90I, I123V, E125D, K131E, and N205S) with respect to the original protein. Notably, these 6 residue changes restore the ability of pH1N1 NS1 to inhibit general host gene expression, mainly by their ability to restore binding to the cellular factor CPSF30. This is the first report describing the ability of the pH1N1 NS1 protein to naturally acquire mutations that restore this function. Importantly, a recombinant pH1N1 virus containing these 6 amino acid changes in the NS1 protein (pH1N1/NSs-6mut) inhibited host IFN and proinflammatory responses to a greater extent than that with the parental virus (pH1N1/NS1-wt), yet virus titers were not significantly increased in cell cultures or in mouse lungs, and the disease was partially attenuated. The pH1N1/NSs-6mut virus grew similarly to pH1N1/NSs-wt in mouse lungs, but infection with pH1N1/NSs-6mut induced lower levels of proinflammatory cytokines, likely due to a general inhibition of gene expression mediated by the mutated NS1 protein. This lower level of inflammation induced by the pH1N1/NSs-6mut virus likely accounts for the attenuated disease phenotype and may represent a host-virus adaptation affecting influenza virus pathogenesis. IMPORTANCE Seasonal influenza A viruses (IAVs) are among the most common causes of respiratory infections in humans. In addition, occasional pandemics are caused when IAVs circulating in other species emerge in the human population. In 2009, a swine-origin H1N1 IAV (pH1N1) was transmitted to humans, infecting people then and up to the present. It was previously shown that the NS1 protein from the 2009 pandemic H1N1 (pH1N1) virus is not able to inhibit general gene expression. However, currently circulating pH1N1 viruses have evolved to encode 6 amino acid changes (E55K, L90I, I123V, E125D, K131E, and N205S) that allow the NS1 protein of contemporary pH1N1 strains to inhibit host gene expression, which correlates with its ability to interact with CPSF30. Infection with a recombinant pH1N1 virus encoding these 6 amino acid changes (pH1N1/NSs-6mut) induced lower levels of proinflammatory cytokines, resulting in viral attenuation in vivo. This might represent an adaptation of pH1N1 virus to humans.

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