scholarly journals N-Linked Glycan Sites on the Influenza A Virus Neuraminidase Head Domain Are Required for Efficient Viral Incorporation and Replication

2020 ◽  
Vol 94 (19) ◽  
Author(s):  
Henrik Östbye ◽  
Jin Gao ◽  
Mira Rakic Martinez ◽  
Hao Wang ◽  
Jan-Willem de Gier ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Surface Antigen ◽  
Influenza A ◽  
Surface Antigens ◽  
Secretory Protein ◽  
Enveloped Viruses ◽  
Virion Incorporation ◽  
Head Domain ◽  
Glycosylation Sites ◽  
Over Time

ABSTRACT N-linked glycans commonly contribute to secretory protein folding, sorting, and signaling. For enveloped viruses, such as the influenza A virus (IAV), large N-linked glycans can also be added to prevent access to epitopes on the surface antigens hemagglutinin (HA or H) and neuraminidase (NA or N). Sequence analysis showed that in the NA head domain of H1N1 IAVs, three N-linked glycosylation sites are conserved and that a fourth site is conserved in H3N2 IAVs. Variable sites are almost exclusive to H1N1 IAVs of human origin, where the number of head glycosylation sites first increased over time and then decreased with and after the introduction of the 2009 pandemic H1N1 IAV of Eurasian swine origin. In contrast, variable sites exist in H3N2 IAVs of human and swine origin, where the number of head glycosylation sites has mainly increased over time. Analysis of IAVs carrying N1 and N2 mutants demonstrated that the N-linked glycosylation sites on the NA head domain are required for efficient virion incorporation and replication in cells and eggs. It also revealed that N1 stability is more affected by the head domain glycans, suggesting N2 is more amenable to glycan additions. Together, these results indicate that in addition to antigenicity, N-linked glycosylation sites can alter NA enzymatic stability and the NA amount in virions. IMPORTANCE N-linked glycans are transferred to secretory proteins upon entry into the endoplasmic reticulum lumen. In addition to promoting secretory protein maturation, enveloped viruses also utilize these large oligosaccharide structures to prevent access to surface antigen epitopes. Sequence analyses of the influenza A virus (IAV) surface antigen neuraminidase (NA or N) showed that the conservation of N-linked glycosylation sites on the NA enzymatic head domain differs by IAV subtype (H1N1 versus H3N2) and species of origin, with human-derived IAVs possessing the most variability. Experimental analyses verified that the N-linked glycosylation sites on the NA head domain contribute to virion incorporation and replication. It also revealed that the head domain glycans affect N1 stability more than N2, suggesting N2 is more accommodating to glycan additions. These results demonstrate that in addition to antigenicity, changes in N-linked glycosylation sites can alter other properties of viral surface antigens and virions.

scholarly journals N-linked glycan sites on the influenza NA head domain are required for efficient IAV incorporation and replication

2020 ◽  
Author(s):  
Henrik Östbye ◽  
Jin Gao ◽  
Mira Rakic Martinez ◽  
Hao Wang ◽  
Jan-Willem de Gier ◽  
...  
Keyword(s):  
Influenza A ◽  
Surface Antigens ◽  
Secretory Protein ◽  
Human Origin ◽  
Time Analysis ◽  
Enveloped Viruses ◽  
Virion Incorporation ◽  
Head Domain ◽  
Glycosylation Sites ◽  
Over Time

ABSTRACTN-linked glycans commonly contribute to secretory protein folding, sorting and signaling. For enveloped viruses such as the influenza A virus (IAV), the addition of large N-linked glycans can also prevent access to epitopes on the surface antigens hemagglutinin (HA or H) and neuraminidase (NA or N). Sequence analysis showed that in the NA head domain of H1N1 IAVs three N-linked glycosylation sites are conserved and that a fourth site is conserved in H3N2 IAVs. Variable sites are almost exclusive to H1N1 IAVs of human origin, where the number of head glycosylation sites first increased and then decreased over time. In contrast, variable sites exist in H3N2 IAVs of human and swine origin, where the number of head glycosylation sites has mainly increased over time. Analysis of IAVs carrying N1 and N2 mutants demonstrated that the N-linked glycosylation sites on the NA head domain are required for efficient virion incorporation and replication in cells or eggs. It also revealed that N1 stability is more affected by the head domain glycans, suggesting N2 is more amenable to glycan additions. Together, these results indicate that in addition to antigenicity, N-linked glycosylation sites can alter NA enzymatic stability and the NA amount in virions.

scholarly journals Effects of Basic Amino Acids and Their Derivatives on SARS-CoV-2 and Influenza-A Virus Infection

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1301
Author(s):  
Ivonne Melano ◽  
Li-Lan Kuo ◽  
Yan-Chung Lo ◽  
Po-Wei Sung ◽  
Ni Tien ◽  
...  
Keyword(s):  
Amino Acids ◽  
Virus Infection ◽  
Influenza A Virus ◽  
Influenza A ◽  
Enveloped Viruses ◽  
Virus Attachment ◽  
Basic Amino Acids ◽  
Ester Derivative ◽  
Endosomal Acidification

Amino acids have been implicated with virus infection and replication. Here, we demonstrate the effects of two basic amino acids, arginine and lysine, and their ester derivatives on infection of two enveloped viruses, SARS-CoV-2, and influenza A virus. We found that lysine and its ester derivative can efficiently block infection of both viruses in vitro. Furthermore, the arginine ester derivative caused a significant boost in virus infection. Studies on their mechanism of action revealed that the compounds potentially disturb virus uncoating rather than virus attachment and endosomal acidification. Our findings suggest that lysine supplementation and the reduction of arginine-rich food intake can be considered as prophylactic and therapeutic regimens against these viruses while also providing a paradigm for the development of broad-spectrum antivirals.

Matrix proteins of enveloped viruses: a case study of Influenza A virus M1 protein

2018 ◽  
Vol 37 (3) ◽  
pp. 671-690 ◽  
Author(s):  
Larisa V. Kordyukova ◽  
Eleonora V. Shtykova ◽  
Lyudmila A. Baratova ◽  
Dmitri I. Svergun ◽  
Oleg V. Batishchev
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Matrix Proteins ◽  
Enveloped Viruses ◽  
M1 Protein

scholarly journals Release of filamentous and spherical influenza A virus is not restricted by tetherin

2012 ◽  
Vol 93 (5) ◽  
pp. 963-969 ◽  
Author(s):  
Emily A. Bruce ◽  
Truus E. Abbink ◽  
Helen M. Wise ◽  
Ruth Rollason ◽  
Rui Pedro Galao ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Infection ◽  
Cellular Protein ◽  
Spherical Particles ◽  
Enveloped Viruses ◽  
Specific Antagonist ◽  
Multiple Strains ◽  
Scanning Electron

The cellular protein tetherin is thought to act as a ‘leash’ that anchors many enveloped viruses to the plasma membrane and prevents their release. We found that replication of multiple strains of influenza A virus was generally insensitive to alteration of tetherin levels, as assessed by output titre or scanning electron microscopy of cell-associated virions. This included human, swine, avian and equine isolates, strains that form filamentous or spherical particles and viruses that lack the M2 or NS1 proteins. Levels of cell-surface tetherin were not reduced by influenza infection, but tetherin and the viral haemagglutinin co-localized on the plasma membrane. However, tetherin could not be detected in filamentous virions, suggesting that influenza may possess a mechanism to exclude it from virions. Overall, if influenza does encode a specific antagonist of tetherin, it is not M2 or NS1 and we find no evidence for a role in host range specificity.

scholarly journals Unique Structural Features of Influenza Virus H15 Hemagglutinin

2017 ◽  
Vol 91 (12) ◽  
Author(s):  
Netanel Tzarum ◽  
Ryan McBride ◽  
Corwin M. Nycholat ◽  
Wenjie Peng ◽  
James C. Paulson ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Antigenic Variation ◽  
Immune Surveillance ◽  
Structural Features ◽  
Human Infection ◽  
Dimensional Structure ◽  
Receptor Binding Site ◽  
Head Domain ◽  
Group 2

ABSTRACT Influenza A H15 viruses are members of a subgroup (H7-H10-H15) of group 2 hemagglutinin (HA) subtypes that include H7N9 and H10N8 viruses that were isolated from humans during 2013. The isolation of avian H15 viruses is, however, quite rare and, until recently, geographically restricted to wild shorebirds and waterfowl in Australia. The HAs of H15 viruses contain an insertion in the 150-loop (loop beginning at position 150) of the receptor-binding site common to this subgroup and a unique insertion in the 260-loop compared to any other subtype. Here, we show that the H15 HA has a high preference for avian receptor analogs by glycan array analyses. The H15 HA crystal structure reveals that it is structurally closest to H7N9 HA, but the head domain of the H15 trimer is wider than all other HAs due to a tilt and opening of the HA1 subunits of the head domain. The extended 150-loop of the H15 HA retains the conserved conformation as in H7 and H10 HAs. Furthermore, the elongated 260-loop increases the exposed HA surface and can contribute to antigenic variation in H15 HAs. Since avian-origin H15 HA viruses have been shown to cause enhanced disease in mammalian models, further characterization and immune surveillance of H15 viruses are warranted. IMPORTANCE In the last 2 decades, an apparent increase has been reported for cases of human infection by emerging avian influenza A virus subtypes, including H7N9 and H10N8 viruses isolated during 2013. H15 is the other member of the subgroup of influenza A virus group 2 hemagglutinins (HAs) that also include H7 and H10. H15 viruses have been restricted to Australia, but recent isolation of H15 viruses in western Siberia suggests that they could be spread more globally via the avian flyways that converge and emanate from this region. Here we report on characterization of the three-dimensional structure and receptor specificity of the H15 hemagglutinin, revealing distinct features and specificities that can aid in global surveillance of such viruses for potential spread and emerging threat to the human population.

scholarly journals Microbiome disturbance and resilience dynamics of the upper respiratory tract in response to influenza A virus infection in humans and ferrets

2018 ◽  
Author(s):  
Drishti Kaul ◽  
Raveen Rathnasinghe ◽  
Marcela Ferres ◽  
Gene S. Tan ◽  
Aldo Barrera ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Respiratory Tract ◽  
Influenza A Virus ◽  
Influenza A ◽  
Cellular Damage ◽  
Upper Respiratory Tract ◽  
Upper Respiratory ◽  
Influenza A Virus Infection ◽  
Over Time

AbstractInfection with influenza can be aggravated by bacterial co-infections, which often results in disease exacerbation because of host responses and cellular damage. The native upper respiratory tract (URT) microbiome likely plays a role, yet the effects of influenza infection on the URT microbiome are largely unknown. We performed a longitudinal study to assess the temporal dynamics of the URT microbiomes of uninfected and influenza virus-infected humans and ferrets. Uninfected human patients and ferret URT microbiomes had stable “heathy ecostate” communities both within and between individuals. In contrast, infected patients and ferrets exhibited large changes in bacterial community composition over time and between individuals. The “unhealthy” ecostates of infected individuals progressed towards the “healthy ecostate” over time, coinciding with viral clearance and recovery. Blooms of Pseudomonas were a statistically associated constant in the disturbed microbiomes of infected individuals. The dynamic and resilient nature of the microbiome during influenza virus infection in multiple hosts provides a compelling rationale for the maintenance of the microbiome homeostasis as a potential therapeutic target to prevent IAV associated bacterial co-infections.One Sentence SummaryDynamics of the upper respiratory tract microbiome during influenza A virus infection

scholarly journals 1350. Therapeutic Effects of Baloxavir Marboxil against Influenza A Virus Infection in Ferrets

2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S413-S413
Author(s):  
Mitsutaka Kitano ◽  
Takanobu Matsuzaki ◽  
Ryoko Oka ◽  
Kaoru Baba ◽  
Takahiro Noda ◽  
...  
Keyword(s):  
Body Temperature ◽  
Oral Administration ◽  
Influenza A Virus ◽  
Influenza A ◽  
Virus Titer ◽  
Therapeutic Effects ◽  
Single Oral Administration ◽  
Influenza A Virus Infection ◽  
Oseltamivir Phosphate ◽  
Over Time

Abstract Background Baloxavir marboxil (BXM) is a novel small molecule inhibitor of cap-dependent endonuclease that is essential for influenza virus transcription and replication. In this study, pharmacokinetic profiles of BXM and baloxavir acid (BXA), an active form of BXM, were first examined in ferrets, and then the therapeutic effects of BXM against influenza A virus infection were compared with that of oseltamivir phosphate in ferrets. Methods The plasma exposure of BXA and BXM was examined after a single oral administration of BXM at doses of 10 and 30 mg/kg. The concentrations in plasma were determined by liquid chromatography-tandem mass spectrometry(LC/MS/MS). For efficacy study, ferrets infected intranasally with A/Kadoma/2006 (H1N1) were administrated 10 or 30 mg/kg of BXM orally twice daily for 1 day, starting at 1 day post-infection (p.i.) or administrated 10 mg/kg of BXM orally twice daily for 1 day, starting at 2 days p.i.. Oseltamivir phosphate was administered at doses of 5 mg/kg orally twice daily for 2 days as a comparison. The virus titer in the nasal washes and body temperature change were monitored during infection. Results BXA was detected in ferret plasma after a single oral administration of BXM at 10 and 30 mg/kg, in more than a dose-proportional manner. When the treatment was initiated at 1 day p.i., BXM at 10 and 30 mg/kg showed reduction of virus titer to an undetectable level on day 2 p.i. and statistically significant reduction in virus titer over time from day 2 to 3 p.i. compared with vehicle and oseltamivir phosphate. Moreover, the change of body temperature over time from 8 hours after the first administration to 3 days p.i. was significantly lower in BXM at 10 and 30 mg/kg than vehicle and oseltamivir phosphate. These effects were also observed in ferrets treated with BXM at 10 mg/kg even when administered at 2 day p.i. where ferret exhibit fever that is more than 1 degree higher than on 1 day p.i.. Conclusion Single-day oral administration of BXM had beneficial effects on viral titer and symptoms in ferrets infected with influenza A virus, which were superior to those observed with oseltamivir phosphate and vehicle. Disclosures M. Kitano, Shionogi & Co., Ltd.: Employee, Salary. T. Matsuzaki, Shionogi & Co., Ltd.: Employee, Salary. R. Oka, Shionogi & Co., Ltd.: Employee, Salary. K. Baba, Shionogi TechnoAdvance Research & Co., Ltd.: Employee, Salary. T. Noda, Shionogi TechnoAdvance Research & Co., Ltd.: Employee, Salary. Y. Yoshida, Shionogi & Co., Ltd.: Employee, Salary. K. Sato, Shionogi & Co., Ltd.: Employee, Salary. R. Yoshida, Shionogi & Co., Ltd.: Employee, Salary. A. Sato, Shionogi & Co., Ltd.: Employee, Salary. H. Kamimori, Shionogi & Co., Ltd.: Employee, Salary. T. Shishido, Shionogi & Co., Ltd.: Employee, Salary. A. Naito, Shionogi & Co., Ltd.: Employee, Salary.

Probability of detecting influenza A virus subtypes H1N1 and H3N2 in individual pig nasal swabs and pen-based oral fluid specimens over time

2013 ◽  
Vol 166 (3-4) ◽  
pp. 450-460 ◽  
Author(s):  
Christa K. Goodell ◽  
John Prickett ◽  
Apisit Kittawornrat ◽  
Fanghong Zhou ◽  
Rolf Rauh ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Oral Fluid ◽  
Nasal Swabs ◽  
Over Time

scholarly journals Incorporation of influenza A virus genome segments does not absolutely require wild-type sequences

2009 ◽  
Vol 90 (7) ◽  
pp. 1734-1740 ◽  
Author(s):  
Ken Fujii ◽  
Makoto Ozawa ◽  
Kiyoko Iwatsuki-Horimoto ◽  
Taisuke Horimoto ◽  
Yoshihiro Kawaoka
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Influenza A ◽  
Virus Genome ◽  
Wild Type ◽  
Genome Packaging ◽  
Viral Rnas ◽  
Virion Incorporation ◽  
Specific Sequences ◽  
Type Sequence

The efficient incorporation of influenza virus genome segments into virions is mediated by cis-acting regions at both ends of the viral RNAs. It was shown previously that nt 16–26 at the 3′ end of the non-structural (NS) viral RNA of influenza A virus are important for efficient virion incorporation and that nt 27–56 also contribute to this process. To understand further the signalling requirements for genome packaging, this study performed linker-scanning mutagenesis in the latter region and found that nt 27–35 made an appreciable contribution to the efficient incorporation of the NS segment. An NS vRNA library was then generated composed of an RNA population with randomized nucleotides at positions 16–35 such that the virus could select the sequences it required for virion incorporation. The sequences selected differed from the wild-type sequence and no conserved nucleotides were selected. The ability of non-wild-type sequences to function in this manner indicates that the incorporation of influenza A virus genome segments does not absolutely require specific sequences.

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