scholarly journals Inhibition of Avian Influenza A Virus Replication in Human Cells by Host Restriction Factor TUFM Is Correlated with Autophagy

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Shu-Ming Kuo ◽  
Chi-Jene Chen ◽  
Shih-Cheng Chang ◽  
Tzu-Jou Liu ◽  
Yi-Hsiang Chen ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Virus Replication ◽  
Influenza A ◽  
Inhibitory Effect ◽  
Human Cells ◽  
Restriction Factor ◽  
Influenza A Viruses ◽  
Host Restriction ◽  
Host Restriction Factor

ABSTRACT Avian influenza A viruses generally do not replicate efficiently in human cells, but substitution of glutamic acid (Glu, E) for lysine (Lys, K) at residue 627 of avian influenza virus polymerase basic protein 2 (PB2) can serve to overcome host restriction and facilitate human infectivity. Although PB2 residue 627 is regarded as a species-specific signature of influenza A viruses, host restriction factors associated with PB2627E have yet to be fully investigated. We conducted immunoprecipitation, followed by differential proteomic analysis, to identify proteins associating with PB2627K (human signature) and PB2627E (avian signature) of influenza A/WSN/1933(H1N1) virus, and the results indicated that Tu elongation factor, mitochondrial (TUFM), had a higher binding affinity for PB2627E than PB2627K in transfected human cells. Stronger binding of TUFM to avian-signature PB2590G/591Q and PB2627E in the 2009 swine-origin pandemic H1N1 and 2013 avian-origin H7N9 influenza A viruses was similarly observed. Viruses carrying avian-signature PB2627E demonstrated increased replication in TUFM-deficient cells, but viral replication decreased in cells overexpressing TUFM. Interestingly, the presence of TUFM specifically inhibited the replication of PB2627E viruses, but not PB2627K viruses. In addition, enhanced levels of interaction between TUFM and PB2627E were noted in the mitochondrial fraction of infected cells. Furthermore, TUFM-dependent autophagy was reduced in TUFM-deficient cells infected with PB2627E virus; however, autophagy remained consistent in PB2627K virus-infected cells. The results suggest that TUFM acts as a host restriction factor that impedes avian-signature influenza A virus replication in human cells in a manner that correlates with autophagy. IMPORTANCE An understanding of the mechanisms that influenza A viruses utilize to shift host tropism and the identification of host restriction factors that can limit infection are both critical to the prevention and control of emerging viruses that cross species barriers to target new hosts. Using a proteomic approach, we revealed a novel role for TUFM as a host restriction factor that exerts an inhibitory effect on avian-signature PB2627E influenza virus propagation in human cells. We further found that increased TUFM-dependent autophagy correlates with the inhibitory effect on avian-signature influenza virus replication and may serve as a key intrinsic mechanism to restrict avian influenza virus infection in humans. These findings provide new insight regarding the TUFM mitochondrial protein and may have important implications for the development of novel antiviral strategies. IMPORTANCE An understanding of the mechanisms that influenza A viruses utilize to shift host tropism and the identification of host restriction factors that can limit infection are both critical to the prevention and control of emerging viruses that cross species barriers to target new hosts. Using a proteomic approach, we revealed a novel role for TUFM as a host restriction factor that exerts an inhibitory effect on avian-signature PB2627E influenza virus propagation in human cells. We further found that increased TUFM-dependent autophagy correlates with the inhibitory effect on avian-signature influenza virus replication and may serve as a key intrinsic mechanism to restrict avian influenza virus infection in humans. These findings provide new insight regarding the TUFM mitochondrial protein and may have important implications for the development of novel antiviral strategies.

scholarly journals Evidence for Avian and Human Host Cell Factors That Affect the Activity of Influenza Virus Polymerase

2010 ◽  
Vol 84 (19) ◽  
pp. 9978-9986 ◽  
Author(s):  
Olivier Moncorgé ◽  
Manuela Mura ◽  
Wendy S. Barclay
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Host Range ◽  
Influenza A ◽  
Human Cells ◽  
Influenza A Viruses ◽  
New Host ◽  
Range Restriction ◽  
Positive Factor

ABSTRACT Typical avian influenza A viruses do not replicate efficiently in humans. The molecular basis of host range restriction and adaptation of avian influenza A viruses to a new host species is still not completely understood. Genetic determinants of host range adaptation have been found on the polymerase complex (PB1, PB2, and PA) as well as on the nucleoprotein (NP). These four viral proteins constitute the minimal set for transcription and replication of influenza viral RNA. It is widely documented that in human cells, avian-derived influenza A viral polymerase is poorly active, but despite extensive study, the reason for this blockade is not known. We monitored the activity of influenza A viral polymerases in heterokaryons formed between avian (DF1) and human (293T) cells. We have discovered that a positive factor present in avian cells enhances the activity of the avian influenza virus polymerase. We found no evidence for the existence of an inhibitory factor for avian virus polymerase in human cells, and we suggest, instead, that the restriction of avian influenza virus polymerases in human cells is the consequence of the absence or the low expression of a compatible positive cofactor. Finally, our results strongly suggest that the well-known adaptative mutation E627K on viral protein PB2 facilitates the ability of a human positive factor to enhance replication of influenza virus in human cells.

scholarly journals Avian Influenza Virus PB1 Gene in H3N2 Viruses Evolved in Humans To Reduce Interferon Inhibition by Skewing Codon Usage toward Interferon-Altered tRNA Pools

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Bartram L. Smith ◽  
Guifang Chen ◽  
Claus O. Wilke ◽  
Robert M. Krug
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Codon Usage ◽  
Avian Influenza Virus ◽  
Influenza A ◽  
Human Cells ◽  
Influenza Viruses ◽  
Human Adaptation ◽  
Influenza A Viruses ◽  
Avian Influenza Viruses

ABSTRACTInfluenza A viruses cause an annual contagious respiratory disease in humans and are responsible for periodic high-mortality human pandemics. Pandemic influenza A viruses usually result from the reassortment of gene segments between human and avian influenza viruses. These avian influenza virus gene segments need to adapt to humans. Here we focus on the human adaptation of the synonymous codons of the avian influenza virus PB1 gene of the 1968 H3N2 pandemic virus. We generated recombinant H3N2 viruses differing only in codon usage of PB1 mRNA and demonstrated that codon usage of the PB1 mRNA of recent H3N2 virus isolates enhances replication in interferon (IFN)-treated human cells without affecting replication in untreated cells, thereby partially alleviating the interferon-induced antiviral state. High-throughput sequencing of tRNA pools explains the reduced inhibition of replication by interferon: the levels of some tRNAs differ between interferon-treated and untreated human cells, and evolution of the codon usage of H3N2 PB1 mRNA is skewed toward interferon-altered human tRNA pools. Consequently, the avian influenza virus-derived PB1 mRNAs of modern H3N2 viruses have acquired codon usages that better reflect tRNA availabilities in IFN-treated cells. Our results indicate that the change in tRNA availabilities resulting from interferon treatment is a previously unknown aspect of the antiviral action of interferon, which has been partially overcome by human-adapted H3N2 viruses.IMPORTANCEPandemic influenza A viruses that cause high human mortality usually result from reassortment of gene segments between human and avian influenza viruses. These avian influenza virus gene segments need to adapt to humans. Here we focus on the human adaptation of the avian influenza virus PB1 gene that was incorporated into the 1968 H3N2 pandemic virus. We demonstrate that the coding sequence of the PB1 mRNA of modern H3N2 viruses enhances replication in human cells in which interferon has activated a potent antiviral state. Reduced interferon inhibition results from evolution of PB1 mRNA codons skewed toward the pools of tRNAs in interferon-treated human cells, which, as shown here, differ significantly from the tRNA pools in untreated human cells. Consequently, avian influenza virus-derived PB1 mRNAs of modern H3N2 viruses have acquired codon usages that better reflect tRNA availabilities in IFN-treated cells and are translated more efficiently.

scholarly journals Characterization of H9N2 influenza A viruses isolated from chicken products imported into Japan from China

2006 ◽  
Vol 135 (3) ◽  
pp. 386-391 ◽  
Author(s):  
M. MASE ◽  
M. ETO ◽  
K. IMAI ◽  
K. TSUKAMOTO ◽  
S. YAMAGUCHI
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Influenza A ◽  
H9n2 Virus ◽  
Amino Acid Substitutions ◽  
Influenza A Viruses ◽  
Potential Sources

We characterized eleven H9N2 influenza A viruses isolated from chicken products imported from China. Genetically they were classified into six distinct genotypes, including five already known genotypes and one novel genotype. This suggested that such multiple genotypes of the H9N2 virus have possibly already become widespread and endemic in China. Two isolates have amino-acid substitutions that confer resistance to amantadine in the M2 region, and this supported the evidence that this mutation might be a result of the wide application of amantadine for avian influenza treatment in China. These findings emphasize the importance of surveillance for avian influenza virus in this region, and of quarantining imported chicken products as potential sources for the introduction of influenza virus.

scholarly journals A double-stranded RNA platform is required for the interaction between a host restriction factor and the NS1 protein of influenza A virus

2019 ◽  
Vol 48 (1) ◽  
pp. 304-315 ◽  
Author(s):  
Guifang Chen ◽  
Li-Chung Ma ◽  
Shanshan Wang ◽  
Ryan L Woltz ◽  
Emily M Grasso ◽  
...  
Keyword(s):  
Amino Acid ◽  
Influenza A ◽  
Binding Activity ◽  
Restriction Factor ◽  
Amino Acid Residues ◽  
Ns1 Protein ◽  
Double Stranded Rna ◽  
Host Restriction ◽  
Host Restriction Factor ◽  
Dsrna Binding

Abstract Influenza A viruses cause widespread human respiratory disease. The viral multifunctional NS1 protein inhibits host antiviral responses. This inhibition results from the binding of specific cellular antiviral proteins at various positions on the NS1 protein. Remarkably, binding of several proteins also requires the two amino-acid residues in the NS1 N-terminal RNA-binding domain (RBD) that are required for binding double-stranded RNA (dsRNA). Here we focus on the host restriction factor DHX30 helicase that is countered by the NS1 protein, and establish why the dsRNA-binding activity of NS1 is required for its binding to DHX30. We show that the N-terminal 152 amino-acid residue segment of DHX30, denoted DHX30N, possesses all the antiviral activity of DHX30 and contains a dsRNA-binding domain, and that the NS1-DHX30 interaction in vivo requires the dsRNA-binding activity of both DHX30N and the NS1 RBD. We demonstrate why this is the case using bacteria-expressed proteins: the DHX30N-NS1 RBD interaction in vitro requires the presence of a dsRNA platform that binds both NS1 RBD and DHX30N. We propose that a similar dsRNA platform functions in interactions of the NS1 protein with other proteins that requires these same two amino-acid residues required for NS1 RBD dsRNA-binding activity.

scholarly journals Duck Interferon-Inducible Transmembrane Protein 3 Mediates Restriction of Influenza Viruses

2015 ◽  
Vol 90 (1) ◽  
pp. 103-116 ◽  
Author(s):  
Graham A. D. Blyth ◽  
Wing Fuk Chan ◽  
Robert G. Webster ◽  
Katharine E. Magor
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Avian Influenza ◽  
Influenza A ◽  
Natural Host ◽  
Endocytic Pathway ◽  
Influenza A Viruses ◽  
Highly Pathogenic ◽  
Terminal Domain ◽  
Antiviral Function

ABSTRACTInterferon-inducible transmembrane proteins (IFITMs) can restrict the entry of a wide range of viruses. IFITM3 localizes to endosomes and can potently restrict the replication of influenza A viruses (IAV) and several other viruses that also enter host cells through the endocytic pathway. Here, we investigate whether IFITMs are involved in protection in ducks, the natural host of influenza virus. We identify and sequence duckIFITM1,IFITM2,IFITM3, andIFITM5. Using quantitative PCR (qPCR), we demonstrate the upregulation of these genes in lung tissue in response to highly pathogenic IAV infection by 400-fold, 30-fold, 30-fold, and 5-fold, respectively. We express each IFITM in chicken DF-1 cells and show duck IFITM1 localizes to the cell surface, while IFITM3 localizes to LAMP1-containing compartments. DF-1 cells stably expressing duck IFITM3 (but not IFITM1 or IFITM2) show increased restriction of replication of H1N1, H6N2, and H11N9 IAV strains but not vesicular stomatitis virus. Although duck and human IFITM3 share only 38% identity, critical residues for viral restriction are conserved. We generate chimeric and mutant IFITM3 proteins and show duck IFITM3 does not require its N-terminal domain for endosomal localization or antiviral function; however, this N-terminal end confers endosomal localization and antiviral function on IFITM1. In contrast to mammalian IFITM3, the conserved YXXθ endocytosis signal sequence in the N-terminal domain of duck IFITM3 is not essential for correct endosomal localization. Despite significant structural and amino acid divergence, presumably due to host-virus coevolution, duck IFITM3 is functional against IAV.IMPORTANCEImmune IFITM genes are poorly conserved across species, suggesting that selective pressure from host-specific viruses has driven this divergence. We wondered whether coevolution between viruses and their natural host would result in the evasion of IFITM restriction. Ducks are the natural host of avian influenza A viruses and display few or no disease symptoms upon infection with most strains, including highly pathogenic avian influenza. We have characterized the duck IFITM locus and identified IFITM3 as an important restrictor of several influenza A viruses, including avian strains. With only 38% amino acid identity to human IFITM3, duck IFITM3 possesses antiviral function against influenza virus. Thus, despite long coevolution of virus and host effectors in the natural host, influenza virus evasion of IFITM3 restriction in ducks is not apparent.

scholarly journals Pathogenicity and Vaccine Efficacy of Different Clades of Asian H5N1 Avian Influenza A Viruses in Domestic Ducks

2008 ◽  
Vol 82 (22) ◽  
pp. 11374-11382 ◽  
Author(s):  
Jeong-Ki Kim ◽  
Patrick Seiler ◽  
Heather L. Forrest ◽  
Alexey M. Khalenkov ◽  
John Franks ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Influenza A ◽  
Preventive Strategy ◽  
Complete Protection ◽  
Influenza A Viruses ◽  
Symptomatic Infection ◽  
Domestic Ducks ◽  
Virus Challenge ◽  
H5n1 Influenza

ABSTRACT Waterfowl represent the natural reservoir of all subtypes of influenza A viruses, including H5N1. Ducks are especially considered major contributors to the spread of H5N1 influenza A viruses because they exhibit diversity in morbidity and mortality. Therefore, as a preventive strategy against endemic as well as pandemic influenza, it is important to reduce the spread of H5N1 influenza A viruses in duck populations. Here, we describe the pathogenicity of dominant clades (clades 1 and 2) of H5N1 influenza A viruses circulating in birds in Asia. Four representatives of dominant clades of the viruses cause symptomatic infection but lead to different profiles of lethality in domestic ducks. We also demonstrate the efficacy, cross-protectiveness, and immunogenicity of three different inactivated oil emulsion whole-virus H5 influenza vaccines (derived by implementing reverse genetics) to the viruses in domestic ducks. A single dose of the vaccines containing 1 μg of hemagglutinin protein provides complete protection against a lethal A/Duck/Laos/25/06 (H5N1) influenza virus challenge, with no evidence of morbidity, mortality, or shedding of the challenge virus. Moreover, two of the three vaccines achieved complete cross-clade or cross-subclade protection against the heterologous avian influenza virus challenge. Interestingly, the vaccines induce low or undetectable titers of hemagglutination inhibition (HI), cross-HI, and/or virus neutralization antibodies. The mechanism of complete protection in the absence of detectable antibody responses remains an open question.

scholarly journals Importin-α7 Is Required for Enhanced Influenza A Virus Replication in the Alveolar Epithelium and Severe Lung Damage in Mice

2014 ◽  
Vol 88 (14) ◽  
pp. 8166-8179 ◽  
Author(s):  
Patricia Resa-Infante ◽  
René Thieme ◽  
Thomas Ernst ◽  
Petra C. Arck ◽  
Harald Ittrich ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Ex Vivo ◽  
Alveolar Epithelium ◽  
Severe Pneumonia ◽  
H1n1 Influenza ◽  
Lung Damage ◽  
Influenza A Viruses ◽  
Mononuclear Infiltration

ABSTRACTInfluenza A viruses recruit components of the nuclear import pathway to enter the host cell nucleus and promote viral replication. Here, we analyzed the role of the nuclear import factor importin-α7 in H1N1 influenza virus pulmonary tropism by using variousex vivoimaging techniques (magnetic resonance imaging, confocal laser scanning microscopy, and correlative light-electron microscopy). We infected importin-α7 gene-deficient (α7−/−) mice with a recombinant H1N1 influenza virus and compared thein vivoviral kinetics with those in wild-type (WT) mice. In WT mice, influenza virus replication in the bronchial and alveolar epithelium already occurred a few days after infection. Accordingly, extensive mononuclear infiltration and alveolar destruction were present in the lungs of infected WT mice, followed by 100% lethality. Conversely, in α7−/−mice, virus replication was restricted mostly to the bronchial epithelium with marginal alveolar infection, resulting in significantly reduced lung damage and enhanced animal survival. To investigate the host immune response during alveolar virus replication, we studied the role of primary macrophages in virus propagation and clearance. The ability of macrophages to support or clear the virus infection, as well as the host cellular immune responses, did not significantly differ between WT and α7−/−mice. However, cytokine and chemokine responses were generally elevated in WT mice, likely reflective of increased viral replication in the lung. In summary, these data show that a cellular factor, importin-α7, is required for enhanced virus replication in the alveolar epithelium, resulting in elevated cytokine and chemokine levels, extensive mononuclear infiltration, and thus, severe pneumonia and enhanced virulence in mice.IMPORTANCEInfluenza A viruses are respiratory pathogens that may cause pneumonia in humans. Viral infection and replication in the alveoli of the respiratory tract are believed to be crucial for the development of the acute respiratory distress syndrome associated with fatal outcomes in influenza virus-infected patients. Here, we report the requirement of a cellular factor, importin-α7, for efficient virus replication in the alveolar epithelium of mice. Using complementaryex vivoimaging approaches, we show that influenza virus replication is restricted to the bronchial epithelium, followed by enhanced survival in importin-α7-deficient mice. In contrast, the presence of this gene results in enhanced virus replication in the alveoli, elevated cytokine and chemokine responses, mononuclear infiltration, alveolar destruction, and 100% lethality in wild-type mice. Taken together, our results show that importin-α7 is particularly required for virus replication in the alveolar epithelium in association with severe pneumonia and death in mice.

scholarly journals Resurrected ancestral influenza A viruses recapitulate the avian-to-mammalian adaptation of European avian-like swine influenza virus

2021 ◽  
Author(s):  
Wen Su ◽  
Rhodri Harfoot ◽  
Yvonne Su ◽  
Jennifer DeBeauchamp ◽  
Udayan Joseph ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Influenza A ◽  
Swine Influenza Virus ◽  
Swine Influenza ◽  
Polymerase Activity ◽  
Influenza Viruses ◽  
Mammalian Host ◽  
Influenza A Viruses ◽  
Sequence Reconstruction

Abstract The emergence of a pandemic influenza virus may be better anticipated if we better understand the evolutionary steps taken by avian influenza viruses as they adapt to mammals. We used ancestral sequence reconstruction to resurrect viruses representing initial adaptive stages of the European avian-like H1N1 virus as it transitioned from avian to swine hosts. We demonstrate that efficient transmissibility in pigs was gained through stepwise adaptation after 1983. These time-dependent adaptations resulted in changes in hemagglutinin receptor binding specificity and increased viral polymerase activity. An NP-R351K mutation under strong positive selection increased the transmissibility of a reconstructed virus. The stepwise-adaptation of a wholly avian influenza virus to a mammalian host suggests a window where targeted intervention may have highest impact. Successful intervention will, however, require strategic coordination of surveillance and risk assessment activities to identify these adapting viruses and guide pandemic preparedness resources.

Influenza A virus transmission: contributing factors and clinical implications

2010 ◽  
Vol 12 ◽  
Author(s):  
Jessica A. Belser ◽  
Taronna R. Maines ◽  
Terrence M. Tumpey ◽  
Jacqueline M. Katz
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Influenza A ◽  
Severe Disease ◽  
Virus Transmission ◽  
Influenza Viruses ◽  
Clinical Implications ◽  
Influenza A Viruses ◽  
Molecular Features ◽  
Efficient Transmission

Efficient human-to-human transmission is a necessary property for the generation of a pandemic influenza virus. To date, only influenza A viruses within the H1–H3 subtypes have achieved this capacity. However, sporadic cases of severe disease in individuals following infection with avian influenza A viruses over the past decade, and the emergence of a pandemic H1N1 swine-origin virus in 2009, underscore the need to better understand how influenza viruses acquire the ability to transmit efficiently. In this review, we discuss the biological constraints and molecular features known to affect virus transmissibility to and among humans. Factors influencing the behaviour of aerosols in the environment are described, and the mammalian models used to study virus transmission are presented. Recent progress in understanding the molecular determinants that confer efficient transmission has identified crucial roles for the haemagglutinin and polymerase proteins; nevertheless, influenza virus transmission remains a polygenic trait that is not completely understood. The clinical implications of this research, including methods currently under investigation to mitigate influenza virus human-to-human transmission, are discussed. A better understanding of the viral determinants necessary for efficient transmission will allow us to identify avian influenza viruses with pandemic potential.

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