Modulation of an Ectodomain Motif in the Influenza A Virus Neuraminidase Alters Tetherin Sensitivity and Results in Virus Attenuation In Vivo

Leyva-Grado, Victor H.; Hai, Rong; Fernandes, Fiona; Belicha-Villanueva, Alan; Carter, Carol; Yondola, Mark A.

doi:10.1016/j.jmb.2013.12.023

Cited by 19 publications

(28 citation statements)

References 60 publications

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“…In this study, we prove that the glycosites in the stalk domain of NA are glycosylated to regulate the activity, affinity, and specificity of NA to modulate IAV replication, suggesting that the glycans in the stalk domain of NA play an important role in the virulence and transmission of IAV. However, the relationship between NA activity and the diversity of the stalk domain, and whether the virus release is regulated by the glycosylation in the stalk domain is still unknown (24,25). Our study here revealed that NA glycosylation is important for IAV virulence and transmission.…”

Section: Discussionmentioning

confidence: 62%

Influenza A surface glycosylation and vaccine design

Lin

Tsai

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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We have shown that glycosylation of influenza A virus (IAV) hemagglutinin (HA), especially at position N-27, is crucial for HA folding and virus survival. However, it is not known whether the glycosylation of HA and the other two major IAV surface glycoproteins, neuraminidase (NA) and M2 ion channel, is essential for the replication of IAV. Here, we show that glycosylation of HA at N-142 modulates virus infectivity and host immune response. Glycosylation of NA in the stalk region affects its structure, activity, and specificity, thereby modulating virus release and virulence, and glycosylation at the catalytic domain affects its thermostability; however, glycosylation of M2 had no effect on its function. In addition, using IAV without the stalk and catalytic domains of NA as a live attenuated vaccine was shown to confer a strong IAVspecific CD8+ T-cell response and a strong cross-strain as well as cross-subtype protection against various virus strains.influenza A virus | glycosylation | vaccine design I nfluenza A viruses (IAV) belong to the Orthomyxoviridae family and can circulate widely and cross interspecies barriers through the highly antigenic drift and shift of the 18 subtypes of HA and 11 subtypes of neuraminidase (NA) (1, 2). In addition, the posttranslational modification of the IAV surface proteins is important to circumvent host defense and support the virus life cycle (3).HA is a major surface glycoprotein of IAV and is involved in viral infection via binding to sialic acid (SA)-containing glycans on the surface of host cell (3). The other major glycoprotein of IAV, NA, is involved in the cleavage of SA on the host cell receptor to facilitate the release of viral particles to infect other cells (4). M2, the third surface protein of IAV, has ion channel activity to regulate virus penetration and uncoating (1). All surface proteins interact with M1 protein for virus assembly and release (5).The modification of HA and NA by N-glycosylation is important in the IAV life cycle (1, 6-8). Previously, we have shown that the glycosylation of HA affects its receptor binding, immune response, and structural stability, and glycosite 27 is essential for retaining the structural integrity of HA and its receptor binding (6, 9). In addition, using the monoglycosylated HA as immunogen, it showed a broader protection against various IAV subtypes compared with the fully glycosylated version (10). However, it is not clear whether the other specific glycosites and their glycan structures on HA regulate its functions. With regard to NA, the functional roles of its glycosylation are not well understood, though N-glycosylation was reported to stabilize the protein from protease digestion and may affect the enzyme activity (11,12). The aim of this study was to understand the functional effects of glycosylation on HA, NA, and M2, and how glycosylation of the surface proteins affects the life cycle of IAV. ResultsGlycosylation of HA at N-142. Because several glycosylation sites (glycosites 27, 40, 176, 303, and 497) on HA are ...

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Section: Discussionmentioning

confidence: 62%

Influenza A surface glycosylation and vaccine design

Lin

Tsai

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Studies employing FLUAV VLP systems provided evidence that release of FLUAV-like particles can be restricted by tetherin (18,23), although some viral NAs counteract tetherin with modest efficiency (20,21,23), potentially by altering tetherin glycosylation (21). However, these studies did not examine HA and NA jointly for tetherin antagonism and/or did not analyze HA and NA proteins from pandemic FLUAV.…”

Section: Discussionmentioning

confidence: 99%

“…Initial studies indicated that FLUAV is only inefficiently inhibited by tetherin or is completely tetherin insensitive (17)(18)(19), while release of FLUAV-like particles is inhibited by tetherin (18). In contrast, subsequent analyses demonstrated appreciable inhibition of FLUAV release by tetherin (20)(21)(22). In addition, evidence for a tetherin-antagonizing activity of certain neuraminidase (NA) proteins was reported (20,23), but the antagonism is believed to be relatively inefficient (21).…”

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confidence: 99%

“…In contrast, subsequent analyses demonstrated appreciable inhibition of FLUAV release by tetherin (20)(21)(22). In addition, evidence for a tetherin-antagonizing activity of certain neuraminidase (NA) proteins was reported (20,23), but the antagonism is believed to be relatively inefficient (21). The surface proteins of several viruses can antagonize tetherin (24)(25)(26)(27)(28)(29), but so far whether combinations of hemagglutinin (HA) and NA can inhibit tetherin has not been examined systematically.…”

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confidence: 99%

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Tetherin Sensitivity of Influenza A Viruses Is Strain Specific: Role of Hemagglutinin and Neuraminidase

Gnirß

Zmora

Błażejewska

et al. 2015

J Virol

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The expression of the antiviral host cell factor tetherin is induced by interferon and can inhibit the release of enveloped viruses from infected cells. The Vpu protein of HIV-1 antagonizes the antiviral activity of tetherin, and tetherin antagonists with Vpulike activity have been identified in other viruses. In contrast, it is incompletely understood whether tetherin inhibits influenza A virus (FLUAV) release and whether FLUAV encodes tetherin antagonists. Here, we show that release of several laboratoryadapted FLUAV strains and a seasonal FLUAV strain is inhibited by tetherin, while pandemic FLUAV A/Hamburg/4/2009 is resistant. Studies with a virus-like particle system and analysis of reassortant viruses provided evidence that the viral hemagglutinin (HA) is an important determinant of tetherin antagonism but requires the presence of its cognate neuraminidase (NA) to inhibit tetherin. Finally, tetherin antagonism by FLUAV was dependent on the virion context, since retrovirus release from tetherin-positive cells was not rescued, and correlated with an HA-and NA-dependent reduction in tetherin expression. In sum, our study identifies HA and NA proteins of certain pandemic FLUAV as tetherin antagonists, which has important implications for understanding FLUAV pathogenesis. IMPORTANCE Influenza A virus (FLUAV) infection is responsible for substantial global morbidity and mortality, and understanding how the virus evades the immune defenses of the host may uncover novel targets for antiviral intervention.Tetherin is an antiviral effector molecule of the innate immune system which can contribute to control of viral invasion. However, it has been unclear whether FLUAV is inhibited by tetherin and whether these viruses encode tetherin-antagonizing proteins. Our observation that several pandemic FLUAV strains can counteract tetherin via their HA and NA proteins identifies these proteins as novel tetherin antagonists and indicates that HA/NA-dependent inactivation of innate defenses may contribute to the efficient spread of pandemic FLUAV.

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“…Contradictory reports soon emerged, however, of viruses inherently sensitive to BST-2 restriction (Gnirss et al, 2015;Hu et al, 2017;Mangeat et al, 2012). Differential abilities of various influenza virus neuraminidases (NA) in circumventing BST-2 activity (Leyva-Grado et al, 2014;Yondola et al, 2011) made it apparent that influenza virus sensitivity to BST-2 is likely to be strain-specific. Further studies supported the possibility that influenza virus NA acts a strainspecific antagonist to BST-2 (Leyva-Grado et al, 2014;Mangeat et al, 2012).…”

Section: Introductionmentioning

confidence: 99%