scholarly journals Mutation of Influenza A Virus PA-X Decreases Pathogenicity in Chicken Embryos and Can Increase the Yield of Reassortant Candidate Vaccine Viruses

2018 ◽  
Vol 93 (2) ◽  
Author(s):  
Saira Hussain ◽  
Matthew L. Turnbull ◽  
Helen M. Wise ◽  
Brett W. Jagger ◽  
Philippa M. Beard ◽  
...  
Keyword(s):  
Host Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Control Measure ◽  
Virus Titer ◽  
Virus Antigen ◽  
Economic Consequences ◽  
Primary Control ◽  
X Protein ◽  
X Gene

ABSTRACTThe PA-X protein of influenza A virus has roles in host cell shutoff and viral pathogenesis. While most strains are predicted to encode PA-X, strain-dependent variations in activity have been noted. We found that PA-X protein from the A/PR/8/34 (PR8) strain had significantly lower repressive activity against cellular gene expression than PA-X proteins from the avian strains A/turkey/England/50-92/91 (H5N1) (T/E) and A/chicken/Rostock/34 (H7N1). Loss of normal PA-X expression, either by mutation of the frameshift site or by truncating the X open reading frame (ORF), had little effect on the infectious virus titer of PR8 or PR8 7:1 reassortants with T/E segment 3 grown in embryonated hens’ eggs. However, in both virus backgrounds, mutation of PA-X led to decreased embryo mortality and lower overall pathology, effects that were more pronounced in the PR8 strain than in the T/E reassortant, despite the low shutoff activity of the PR8 PA-X. Purified PA-X mutant virus particles displayed an increased ratio of hemagglutinin (HA) to nucleoprotein (NP) and M1 compared to values for their wild-type (WT) counterparts, suggesting altered virion composition. When the PA-X gene was mutated in the background of poorly growing PR8 6:2 vaccine reassortant analogues containing the HA and neuraminidase (NA) segments from H1N1 2009 pandemic viruses or from an avian H7N3 strain, HA yield increased up to 2-fold. This suggests that the PR8 PA-X protein may harbor a function unrelated to host cell shutoff and that disruption of the PA-X gene has the potential to improve the HA yield of vaccine viruses.IMPORTANCEInfluenza A virus is a widespread pathogen that affects both humans and a variety of animal species, causing regular epidemics and sporadic pandemics, with major public health and economic consequences. A better understanding of virus biology is therefore important. The primary control measure is vaccination, which for humans mostly relies on antigens produced in eggs from PR8-based viruses bearing the glycoprotein genes of interest. However, not all reassortants replicate well enough to supply sufficient virus antigen for demand. The significance of our research lies in identifying that mutation of the PA-X gene in the PR8 strain of virus can improve antigen yield, potentially by decreasing the pathogenicity of the virus in embryonated eggs.

scholarly journals Mutation of influenza A virus PA-X decreases pathogenicity in chicken embryos and can increase the yield of reassortant candidate vaccine viruses

2018 ◽  
Author(s):  
Saira Hussain ◽  
Matthew L. Turnbull ◽  
Helen M. Wise ◽  
Brett W. Jagger ◽  
Philippa M. Beard ◽  
...  
Keyword(s):  
Host Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Control Measure ◽  
Virus Antigen ◽  
Economic Consequences ◽  
Primary Control ◽  
X Protein ◽  
Virus Particles ◽  
X Gene

AbstractThe PA-X protein of influenza A virus has roles in host cell shut-off and viral pathogenesis. While most strains are predicted to encode PA-X, strain-dependent variations in activity have been noted. We found that PA-X protein from A/PR/8/34 (PR8) strain had significantly lower repressive activity against cellular gene expression compared with PA-Xs from the avian strains A/turkey/England/50-92/91 (H5N1) (T/E) and A/chicken/Rostock/34 (H7N1). Loss of normal PA-X expression, either by mutation of the frameshift site or by truncating the X-ORF, had little effect on the infectious virus titre of PR8 or PR8 7:1 reassortants with T/E segment 3 grown in embryonated hens’ eggs. However, in both virus backgrounds, mutation of PA-X led to decreased embryo mortality and lower overall pathology; effects that were more pronounced in the PR8 strain than the T/E reassortant, despite the low shut-off activity of the PR8 PA-X. Purified PA-X mutant virus particles displayed an increased ratio of HA to NP and M1 compared to their WT counterparts, suggesting altered virion composition. When the PA-X gene was mutated in the background of poorly growing PR8 6:2 vaccine reassortant analogues containing the HA and NA segments from H1N1 2009 pandemic viruses or an avian H7N3 strain, HA yield increased up to 2-fold. This suggests that the PR8 PA-X protein may harbour a function unrelated to host cell shut-off and that disruption of the PA-X gene has the potential to improve the HA yield of vaccine viruses.IMPORTANCEInfluenza A virus is a widespread pathogen that affects both man and a variety of animal species, causing regular epidemics and sporadic pandemics with major public health and economic consequences. A better understanding of virus biology is therefore important. The primary control measure is vaccination, which for humans, mostly relies on antigens produced in eggs from PR8-based viruses bearing the glycoprotein genes of interest. However, not all reassortants replicate well enough to supply sufficient virus antigen for demand. The significance of our research lies in identifying that mutation of the PA-X gene in the PR8 strain of virus can improve antigen yield, potentially by decreasing the pathogenicity of the virus in embryonated eggs.

scholarly journals Suppression of influenza A virus replication in human lung epithelial cells by noncytotoxic concentrations bafilomycin A1

2015 ◽  
Vol 308 (3) ◽  
pp. L270-L286 ◽  
Author(s):  
Behzad Yeganeh ◽  
Saeid Ghavami ◽  
Andrea L. Kroeker ◽  
Thomas H. Mahood ◽  
Gerald L. Stelmack ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Host Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Life Cycles ◽  
Host Cells ◽  
Nuclear Accumulation ◽  
Low Concentration ◽  
High Concentrations ◽  
The Impact

Subcellular trafficking within host cells plays a critical role in viral life cycles, including influenza A virus (IAV). Thus targeting relevant subcellular compartments holds promise for effective intervention to control the impact of influenza infection. Bafilomycin A1(Baf-A1), when used at relative high concentrations (≥10 nM), inhibits vacuolar ATPase (V-ATPase) and reduces endosome acidification and lysosome number, thus inhibiting IAV replication but promoting host cell cytotoxicity. We tested the hypothesis that much lower doses of Baf-A1also have anti-IAV activity, but without toxic effects. Thus we assessed the antiviral activity of Baf-A1at different concentrations (0.1–100 nM) in human alveolar epithelial cells (A549) infected with IAV strain A/PR/8/34 virus (H1N1). Infected and mock-infected cells pre- and cotreated with Baf-A1were harvested 0–24 h postinfection and analyzed by immunoblotting, immunofluorescence, and confocal and electron microscopy. We found that Baf-A1had disparate concentration-dependent effects on subcellular organelles and suppressed affected IAV replication. At concentrations ≥10 nM Baf-A1inhibited acid lysosome formation, which resulted in greatly reduced IAV replication and release. Notably, at a very low concentration of 0.1 nM that is insufficient to reduce lysosome number, Baf-A1retained the capacity to significantly impair IAV nuclear accumulation as well as IAV replication and release. In contrast to the effects of high concentrations of Baf-A1, very low concentrations did not exhibit cytotoxic effects or induce apoptotic cell death, based on morphological and FACS analyses. In conclusion, our results reveal that low-concentration Baf-A1is an effective inhibitor of IAV replication, without impacting host cell viability.

Host cell interactome of PA protein of H5N1 influenza A virus in chicken cells

2016 ◽  
Vol 136 ◽  
pp. 48-54 ◽  
Author(s):  
Qiao Wang ◽  
Qinghe Li ◽  
Ranran Liu ◽  
Maiqing Zheng ◽  
Jie Wen ◽  
...  
Keyword(s):  
Host Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
H5n1 Influenza

Influenza A virus uses the aggresome processing machinery for host cell entry

Science ◽  
2014 ◽  
Vol 346 (6208) ◽  
pp. 473-477 ◽  
Author(s):  
Indranil Banerjee ◽  
Yasuyuki Miyake ◽  
Samuel Philip Nobs ◽  
Christoph Schneider ◽  
Peter Horvath ◽  
...  
Keyword(s):  
Host Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Cell Entry ◽  
Processing Machinery ◽  
Host Cell Entry

scholarly journals EXPERIMENTAL INFECTION WITH INFLUENZA A VIRUS IN MICE

1941 ◽  
Vol 73 (1) ◽  
pp. 43-55 ◽  
Author(s):  
R. M. Taylor
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Lethal Dose ◽  
Virus Titer ◽  
Immune Serum ◽  
Normal Serum ◽  
Sublethal Dose ◽  
Virus Content ◽  
Proportional Increase ◽  
Intranasal Instillation

Following intranasal inoculation of influenza A virus (strain PR8) there is a rapid increase of the virus in the lungs which with large doses reaches a maximum within 24 hours. With smaller doses, although the proportional increase is greater, the maximum concentration is not reached until 48 hours following inoculation. If a lethal dose is administered, the ultimate concentration of the virus in the lungs is the same, irrespective of the size of the dose. If a sublethal dose is given, the titer of the virus in the lungs does not achieve the titer reached in mice receiving a lethal dose. Within 48 hours following inoculation of a sublethal dose the lungs of a mouse may contain at least 76,000 M.L.D., yet the mouse survives. The intranasal instillation of sterile fluid (distilled water, varying concentrations of NaCl, broth, or 10 per cent normal serum) into a mouse sublethally infected produces a sharp rise in the virus content of the lung usually followed by death within 3 to 8 days. If, however, the instillate consists of 10 per cent immune serum, there is no rise in the virus titer, and no apparent harm results from the instillation. The implications of these phenomena are discussed and an hypothesis presented to explain their occurrence.

scholarly journals Host Cell Copper Transporters CTR1 and ATP7A are important for Influenza A virus replication

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Jonathan C. Rupp ◽  
Manon Locatelli ◽  
Alexis Grieser ◽  
Andrea Ramos ◽  
Patricia J. Campbell ◽  
...  
Keyword(s):  
Host Cell ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Copper Transporters

scholarly journals Reorganization of the host cell Crk(L)–PI3 kinase signaling complex by the influenza A virus NS1 protein

Virology ◽  
2015 ◽  
Vol 484 ◽  
pp. 146-152 ◽  
Author(s):  
Leena Ylösmäki ◽  
Constanze Schmotz ◽  
Erkko Ylösmäki ◽  
Kalle Saksela
Keyword(s):  
Host Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Pi3 Kinase ◽  
Ns1 Protein ◽  
Kinase Signaling ◽  
Signaling Complex

scholarly journals Molecular Docking of Broad-Spectrum Antibodies on Hemagglutinins of Influenza A Virus

2019 ◽  
Vol 15 ◽  
pp. 117693431987693
Author(s):  
Khanh PB Le ◽  
Phuc-Chau Do ◽  
Rommie E Amaro ◽  
Ly Le
Keyword(s):  
Influenza A Virus ◽  
Broad Spectrum ◽  
Influenza A ◽  
Rational Design ◽  
Interaction Analysis ◽  
Virus Antigen ◽  
Influenza Viruses ◽  
Antigen Binding ◽  
Universal Vaccine ◽  
In Silico Studies

Influenza A has caused several deadly pandemics throughout human history. The virus is often resistant to developed treatments because of its genetic drift or shift property. Broad-spectrum antibodies show a promising potential to overcome the resistance of influenza viruses. In silico studies on broad-reactive antibodies and their interactions with hemagglutinins might shed light on the rational design of a universal vaccine. In this study, 11 broad-spectrum antibodies (or antigen-binding fragments) and 14 hemagglutinins of H3N2 and H5N1 strains were docked and analyzed to provide information about the construction of the scaffold for using universal antibodies against the influenza A virus. Antigen-binding fragments that have high number of appearances in the top 3 within each H3 and H5 subtypes were chosen for protein-protein interaction analysis. The results show that while the hydrogen bond is important for Ab/Fab binding to H3, the H5-Ab/Fab system may need cation-pi interaction for a strong interaction.

scholarly journals Influenza A Virus Disturbs the Host Cell Protein Homeostasis by Inducing the Accumulation of Insoluble Proteins

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 69
Author(s):  
Mariana Marques ◽  
Marisa Pereira ◽  
Maria João Amorim ◽  
Ana Raquel Soares ◽  
Daniela Ribeiro
Keyword(s):  
Endoplasmic Reticulum ◽  
Host Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Early Time ◽  
The Elderly ◽  
Cell Protein ◽  
High Morbidity ◽  
Protein Homeostasis ◽  
Host Cell Protein

Influenza A virus (IAV) is the causative agent for most of the annual respiratory epidemics in humans and the major influenza pandemics in the last century, and is associated with high morbidity and mortality, especially in the elderly. In order to efficiently replicate, this virus hijacks the host cellular machinery and requires precise interactions with host components. However, cells have evolved specific defense mechanisms to counteract the effects induced by the virus. In fact, upon IAV infection, several processes within the cytosol and the endoplasmic reticulum, related to protein synthesis and processing, have shown to contribute either as part of an effective replication cycle or as part of an effective cellular antiviral response. Recent reports show contradictory findings regarding the control of the cellular proteostasis mechanisms by both the virus and the host cell. With this study, we aimed to further unravel the interplay between IAV and the host cell proteostasis-related mechanisms at early time-points post-infection. Our results suggest that the virus disturbs host cell protein homeostasis by inducing the accumulation of insoluble proteins in a process that seems to be related to viral RNA processing. We further analyzed the interplay between IAV infection and the endoplasmic reticulum unfolded protein response. Our results may lead to a better understanding of the interplay between IAV and the host cell and, furthermore, contribute to the development of novel antiviral strategies.

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