The NS1 gene from bat-derived influenza-like virus H17N10 can be rescued in influenza A PR8 backbone

Zhao, Xuejin; Tefsen, Boris; Li, Yan; Qi, Jianxun; Lu, Guangwen; Shi, Yi; Yan, Jinghua; Xiao, Haixia; Gao, George F.

doi:10.1099/jgv.0.000509

Cited by 12 publications

(9 citation statements)

References 45 publications

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“…A major role of NS1 during FLUAV infection is to antagonize the host innate interferon (IFN) system through multiple mechanisms, some of which appear to be strain dependent ( 22 – 31 ). We and others have recently demonstrated that bat FLUAV NS1 proteins, like classical FLUAVs, harbor a structurally and functionally conserved N-terminal double-stranded RNA-binding domain that is critical for potent IFN antagonism in human cells ( 15 , 32 , 33 ). The C-terminal effector domain (ED) of bat FLUAV NS1 may play a minor role in supporting IFN antagonism in vitro ( 15 ), possibly by promoting NS1 oligomerization ( 34 – 37 ).…”

Section: Introductionmentioning

confidence: 99%

Unexpected Functional Divergence of Bat Influenza Virus NS1 Proteins

Turkington

Juozapaitis

Tsolakos

et al. 2018

J Virol

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Recently, two influenza A virus (FLUAV) genomes were identified in Central and South American bats. These sequences exhibit notable divergence from classical FLUAV counterparts, and functionally, bat FLUAV glycoproteins lack canonical receptor binding and destroying activity. Nevertheless, other features that distinguish these viruses from classical FLUAVs have yet to be explored. Here, we studied the viral nonstructural protein NS1, a virulence factor that modulates host signaling to promote efficient propagation. Like all FLUAV NS1 proteins, bat FLUAV NS1s bind double-stranded RNA and act as interferon antagonists. Unexpectedly, we found that bat FLUAV NS1s are unique in being unable to bind host p85β, a regulatory subunit of the cellular metabolism-regulating enzyme, phosphoinositide 3-kinase (PI3K). Furthermore, neither bat FLUAV NS1 alone nor infection with a chimeric bat FLUAV efficiently activates Akt, a PI3K effector. Structure-guided mutagenesis revealed that the bat FLUAV NS1-p85β interaction can be reengineered (in a strain-specific manner) by changing two to four NS1 residues (96L, 99M, 100I, and 145T), thereby creating a hydrophobic patch. Notably, ameliorated p85β-binding is insufficient for bat FLUAV NS1 to activate PI3K, and a chimeric bat FLUAV expressing NS1 with engineered hydrophobic patch mutations exhibits cell-type-dependent, but species-independent, propagation phenotypes. We hypothesize that bat FLUAV hijacking of PI3K in the natural bat host has been selected against, perhaps because genes in this metabolic pathway were differentially shaped by evolution to suit the unique energy use strategies of this flying mammal. These data expand our understanding of the enigmatic functional divergence between bat FLUAVs and classical mammalian and avian FLUAVs.IMPORTANCE The potential for novel influenza A viruses to establish infections in humans from animals is a source of continuous concern due to possible severe outbreaks or pandemics. The recent discovery of influenza A-like viruses in bats has raised questions over whether these entities could be a threat to humans. Understanding unique properties of the newly described bat influenza A-like viruses, such as their mechanisms to infect cells or how they manipulate host functions, is critical to assess their likelihood of causing disease. Here, we characterized the bat influenza A-like virus NS1 protein, a key virulence factor, and found unexpected functional divergence of this protein from counterparts in other influenza A viruses. Our study dissects the molecular changes required by bat influenza A-like virus NS1 to adopt classical influenza A virus properties and suggests consequences of bat influenza A-like virus infection, potential future evolutionary trajectories, and intriguing virus-host biology in bat species.

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Section: Introductionmentioning

confidence: 99%

Unexpected Functional Divergence of Bat Influenza Virus NS1 Proteins

Turkington

Juozapaitis

Tsolakos

et al. 2018

J Virol

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“…Indeed, infection with bat NS1-expressing IAVs resulted in higher levels of IRF3 activation and IFN induction in cells and mice, consistent with an impaired ability of the NS1 from bat influenza A-like viruses to block the RIG-I-sensing pathway and IFN induction in virus-infected cells. Thus, despite the observed inhibition of IFN induction in the context of overexpression (22,23), the NS1 proteins of bat influenza A-like viruses are less capable of inhibiting IFN induction than the NS1 protein from a conventional IAV in the context of infection, illustrating that overexpression of a gene product may lead to biologically misleading conclusions compared to those drawn after productive viral replication in mammalian systems.…”

Section: Discussionmentioning

confidence: 96%

“…More interestingly, these interactions have been proposed to be a species-specific signature for several influenza A virus strains (18)(19)(20)(21). In particular, experiments in which the NS1 protein from HL17NL10 and HL18NL11 (denoted NS1HL17 and NS1HL18 proteins, respectively) was overexpressed demonstrated the effective specific inhibition of IFN induction by NS1 but did not indicate that NS1 blocked general host gene expression (22,23). However, other authors showed that truncations of NS1HL17 and NS1HL18 did not dramatically affect viral lung replication in mice in the context of chimeric viruses containing the glycoproteins HA and NA from influenza A/Puerto Rico/8/1934 (PR8) H1N1 viruses and all the internal proteins from the HL17NL10 and HL18NL11 viruses (6).…”

mentioning

confidence: 99%

Specific Mutations in the PB2 Protein of Influenza A Virus Compensate for the Lack of Efficient Interferon Antagonism of the NS1 Protein of Bat Influenza A-Like Viruses

Aydillo

Ayllón

Pavlisin

et al. 2018

J Virol

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Recently, two new influenza A-like viruses have been discovered in bats, A/little yellow-shouldered bat/Guatemala/060/2010 (HL17NL10) and A/flat-faced bat/Peru/033/2010 (HL18NL11). The hemagglutinin (HA)-like (HL) and neuraminidase (NA)-like (NL) proteins of these viruses lack hemagglutination and neuraminidase activities, despite their sequence and structural homologies with the HA and NA proteins of conventional influenza A viruses. We have now investigated whether the NS1 proteins of the HL17NL10 and HL18NL11 viruses can functionally replace the NS1 protein of a conventional influenza A virus. For this purpose, we generated recombinant influenza A/Puerto Rico/8/1934 (PR8) H1N1 viruses containing the NS1 protein of the PR8 wild-type, HL17NL10, and HL18NL11 viruses. These viruses (r/NS1PR8, r/NS1HL17, and r/NS1HL18, respectively) were tested for replication in bat and nonbat mammalian cells and in mice. Our results demonstrate that the r/NS1HL17 and r/NS1HL18 viruses are attenuated and However, the bat NS1 recombinant viruses showed a phenotype similar to that of the r/NS1PR8 virus in STAT1 human A549 cells and mice, both and systems being unable to respond to interferon (IFN). Interestingly, multiple mouse passages of the r/NS1HL17 and r/NS1HL18 viruses resulted in selection of mutant viruses containing single amino acid mutations in the viral PB2 protein. In contrast to the parental viruses, virulence and IFN antagonism were restored in the selected PB2 mutants. Our results indicate that the NS1 protein of bat influenza A-like viruses is less efficient than the NS1 protein of its conventional influenza A virus NS1 counterpart in antagonizing the IFN response and that this deficiency can be overcome by the influenza virus PB2 protein. Significant gaps in our understanding of the basic features of the recently discovered bat influenza A-like viruses HL17NL10 and HL18NL11 remain. The basic biology of these unique viruses displays both similarities to and differences from the basic biology of conventional influenza A viruses. Here, we show that recombinant influenza A viruses containing the NS1 protein from HL17NL10 and HL18NL11 are attenuated. This attenuation was mediated by their inability to antagonize the type I IFN response. However, this deficiency could be compensated for by single amino acid replacements in the PB2 gene. Our results unravel a functional divergence between the NS1 proteins of bat influenza A-like and conventional influenza A viruses and demonstrate an interplay between the viral PB2 and NS1 proteins to antagonize IFN.

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“…Whereas NP of bat virus origin, and to a certain degree also the polymerase subunit PB2, supported the polymerase activity of the H1N1, H2N2, H3N2, H5N1 and H7N9 subtypes in polymerase reconstitution assays, PB1 and PA did not [34,35,37]. In addition, as the bat IAV non-structural protein 1 (NS1) was previously shown to share the dsRNA-binding property and IFN-suppression characteristics of conventional IAV NS1s [38], an infectious recombinant PR8 virus encoding the NS1 but not NEP gene of HL17NL10 could be generated [39]. Thus, the combination of both incompatible packaging sequences and incompatible viral proteins has likely contributed to the failure to exchange genetic information between bat and conventional IAVs.…”

Section: Bat Iavs Fail To Reassort With Conventional Iavsmentioning

confidence: 99%

Novel insights into bat influenza A viruses

Ciminski

Thamamongood

Zimmer³

et al. 2017

Journal of General Virology

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In 2012 and 2013, influenza virus genome sequences of two new influenza A virus (IAV) subtypes were discovered in bat specimens, but further characterization was largely impeded by the lack of infectious virus. With the identification of highly susceptible cell lines, reconstitution of infectious bat IAV by reverse genetics recently succeeded and allowed a first insight into the life cycle of these viruses. Although there is a certain degree of functional compatibility between bat and conventional influenza A virus proteins, there are striking differences, including receptor usage, polarity of infection and reassortment potential.

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The NS1 gene from bat-derived influenza-like virus H17N10 can be rescued in influenza A PR8 backbone

Cited by 12 publications

References 45 publications

Unexpected Functional Divergence of Bat Influenza Virus NS1 Proteins

Unexpected Functional Divergence of Bat Influenza Virus NS1 Proteins

Specific Mutations in the PB2 Protein of Influenza A Virus Compensate for the Lack of Efficient Interferon Antagonism of the NS1 Protein of Bat Influenza A-Like Viruses

Novel insights into bat influenza A viruses

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