Variations outside the conserved motifs of PB1 catalytic active site may affect replication efficiency of the RNP complex of influenza A virus

Both influenza A virus surface glycoproteins, the haemagglutinin (HA) and neuraminidase (NA), interact with neuraminic acid-containing receptors. The influenza virus A/Charlottesville/31/95 (H1N1) has shown a substantially reduced sensitivity to NA inhibitor compared with the A/WSN/33 (H1N1) isolate by plaque-reduction assays in Madin–Darby canine kidney (MDCK) cells. However, there was no difference in drug sensitivity in an NA inhibition assay. The replacement of the HA gene of A/WSN/33 with the HA gene of A/Charlottesville/31/95 led to a drastic reduction in sensitivity of A/WSN/33 to NA inhibitor in MDCK cells. Passage of A/Charlottesville/31/95 in cell culture in the presence of an NA inhibitor resulted in the emergence of mutant viruses (delNA) whose genomes lacked the coding capacity for the NA active site. The delNA mutants were plaque-to-plaque purified and further characterized. The delNA-31 mutant produced appreciable yields (∼106 p.f.u./ml) in MDCK cell culture supernatants in the absence of viral or bacterial NA activity. Sequence analysis of the delNA mutant genome revealed no compensatory substitutions in the HA or other genes compared with the wild-type. Our data indicate that sialylation of the oligosaccharide chains in the vicinity of the HA receptor-binding site of A/Charlottesville/31/95 virus reduces the HA binding efficiency and thus serves as a compensatory mechanism for the loss of NA activity. Hyperglycosylation of HA is common in influenza A viruses circulating in humans and has the potential to reduce virus sensitivity to NA inhibitors.

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Replication Efficiency of Influenza A Virus H9N2: A Comparative Analysis Between Different Origin Cell Types

Jundishapur Journal of Microbiology ◽

10.5812/jjm.8584 ◽

2013 ◽

Vol 6 (9) ◽

Cited By ~ 4

Author(s):

Nima Zarrin Lebas ◽

Shahla Shahsavandi ◽

Ashraf Mohammadi ◽

Mohammad Majid Ebrahimi ◽

Mehran Bakhshesh

Keyword(s):

Comparative Analysis ◽

Influenza A Virus ◽

Influenza A ◽

Cell Types ◽

Replication Efficiency ◽

Different Origin

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Mutations in the M-Gene Segment Can Substantially Increase Replication Efficiency of NS1 Deletion Influenza A Virus in MDCK Cells

Journal of Virology ◽

10.1128/jvi.01725-12 ◽

2012 ◽

Vol 86 (22) ◽

pp. 12341-12350 ◽

Cited By ~ 10

Author(s):

R. van Wielink ◽

M. M. Harmsen ◽

D. E. Martens ◽

B. P. H. Peeters ◽

R. H. Wijffels ◽

...

Keyword(s):

Influenza A Virus ◽

Influenza A ◽

Mdck Cells ◽

Gene Segment ◽

M Gene ◽

Replication Efficiency

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The PB1 segment of an influenza A virus H1N1 2009pdm isolate enhances the replication efficiency of specific influenza vaccine strains in cell culture and embryonated eggs

Journal of General Virology ◽

10.1099/jgv.0.000390 ◽

2016 ◽

Vol 97 (3) ◽

pp. 620-631 ◽

Cited By ~ 9

Author(s):

Ahmed Mostafa ◽

Pumaree Kanrai ◽

John Ziebuhr ◽

Stephan Pleschka

Keyword(s):

Cell Culture ◽

Influenza Vaccine ◽

Influenza A Virus ◽

Influenza A ◽

Virus H1n1 ◽

Replication Efficiency

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PA from a Recent H9N2 (G1-Like) Avian Influenza A Virus (AIV) Strain Carrying Lysine 367 Confers Altered Replication Efficiency and Pathogenicity to Contemporaneous H5N1 in Mammalian Systems

Viruses ◽

10.3390/v12091046 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1046

Author(s):

Ahmed Mostafa ◽

Sara H. Mahmoud ◽

Mahmoud Shehata ◽

Christin Müller ◽

Ahmed Kandeil ◽

...

Keyword(s):

Avian Influenza ◽

Influenza A Virus ◽

Influenza A ◽

Polymerase Activity ◽

Wild Type ◽

Genetic Compatibility ◽

Bronchial Epithelial ◽

Replication Efficiency ◽

Avian Influenza A Virus ◽

Replication Fitness

Egypt is a hotspot for H5- and H9-subtype avian influenza A virus (AIV) infections and co-infections in poultry by both subtypes have been frequently reported. However, natural genetic reassortment of these subtypes has not been reported yet. Here, we evaluated the genetic compatibility and replication efficiency of reassortants between recent isolates of an Egyptian H5N1 and a H9N2 AIV (H5N1EGY and H9N2EGY). All internal viral proteins-encoding segments of the contemporaneous G1-like H9N2EGY, expressed individually and in combination in the genetic background of H5N1EGY, were genetically compatible with the other H5N1EGY segments. At 37 °C the replication efficiencies of H5N1EGY reassortants expressing the H9N2EGY polymerase subunits PB2 and PA (H5N1PB2-H9N2EGY, H5N1PA-H9N2EGY) were higher than the wild-type H5N1EGY in Madin-Darby canine kidney (MDCK-II) cells. This could not be correlated to viral polymerase activity as this was found to be improved for H5N1PB2-H9N2EGY, but reduced for H5N1PA-H9N2EGY. At 33 °C and 39 °C, H5N1PB2-H9N2EGY and H5N1PA-H9N2EGY replicated to higher levels than the wild-type H5N1EGY in human Calu-3 and A549 cell lines. Nevertheless, in BALB/c mice both reassortants caused reduced mortality compared to the wild-type H5N1EGY. Genetic analysis of the polymerase-encoding segments revealed that the PAH9N2EGY and PB2H9N2EGY encode for a distinct uncharacterized mammalian-like variation (367K) and a well-known mammalian signature (591K), respectively. Introducing the single substitution 367K into the PA of H5N1EGY enabled the mutant virus H5N1PA-R367K to replicate more efficiently at 37 °C in primary human bronchial epithelial (NHBE) cells and also in A549 and Calu-3 cells at 33 °C and 39 °C. Furthermore, H5N1PA-R367K caused higher mortality in BALB/c mice. These findings demonstrate that H5N1 (Clade 2.2.1.2) reassortants carrying internal proteins-encoding segments of G1-like H9N2 viruses can emerge and may gain improved replication fitness. Thereby such H5N1/H9N2 reassortants could augment the zoonotic potential of H5N1 viruses, especially by acquiring unique mammalian-like aa signatures.

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The antiviral mechanism of MxA revealed by a molecular docking-based structural model of the complex of MxA and influenza A virus NP/RNPs

10.1101/219915 ◽

2017 ◽

Author(s):

Yeping Sun

Keyword(s):

Crystal Structure ◽

Influenza A Virus ◽

Influenza A ◽

Molecular Mechanisms ◽

Structural Model ◽

Restriction Factor ◽

Host Restriction ◽

Host Restriction Factor ◽

Rnp Complex ◽

Antiviral Mechanism

AbstractMxA, a member of the dynamin superfamily, is a potent host restriction factor for influenza A virus replication. The viral nucleoprotein (NP) of influenza A virus has been suggested to be a target of MxA. However, the molecular details of the interactions between NP and MxA remain unknown. In the present study, loop L4 of MxA, which was shown to target viral component and is missing in the crystal structure of MxA was modeled on a dimer of the MxA. The dimer was then docked onto NP. The resulting NP-MxA dimer complex is in agreement with previous studies, as the interface contains many residues that were previously identified to be associated with MxA resistance. And the model was the used to construct NP-MxA ring. We also constructed a structural model of the complex of influenza virus NP and polymerase, and the NP residues that interact with MxA in the NP-MxA model partly overlap with those in the NP-polymerase model, so MxA may competitively inhibit the binding of NP and the polymerase and disrupt the assembly of ribonucleoprotein (RNP) complex. These results of this work represent a putative molecular mechanisms for MxA antiviral activity.

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