Review for "Comprehensive assessment of amino acid substitutions in the trimeric RNA polymerase complex of influenza A virus detected in clinical trials of baloxavir marboxil"

Influenza A virus (IAV) replicates in the upper respiratory tract of humans at 33 °C and in the intestinal tract of birds at close to 41 °C. The viral RNA polymerase complex comprises three subunits (PA, PB1 and PB2) and plays an important role in host adaptation. We therefore developed an in vitro system to examine the temperature sensitivity of IAV RNA polymerase complexes from different origins. Complexes were prepared from human lung epithelial cells (A549) using a novel adenoviral expression system. Affinity-purified complexes were generated that contained either all three subunits (PA/PB1/PB2) from the A/Viet/1203/04 H5N1 virus (H/H/H) or the A/WSN/33 H1N1 strain (W/W/W). We also prepared chimeric complexes in which the PB2 subunit was exchanged (H/H/W, W/W/H) or substituted with an avian PB2 from the A/chicken/Nanchang/3-120/01 H3N2 strain (W/W/N). All complexes were functional in transcription, cap-binding and endonucleolytic activity. Complexes containing the H5N1 or Nanchang PB2 protein retained transcriptional activity over a broad temperature range (30–42 °C). In contrast, complexes containing the WSN PB2 protein lost activity at elevated temperatures (39 °C or higher). The E627K mutation in the avian PB2 was not required for this effect. Finally, the avian PB2 subunit was shown to confer enhanced stability to the WSN 3P complex. These results show that PB2 plays an important role in regulating the temperature optimum for IAV RNA polymerase activity, possibly due to effects on the functional stability of the 3P complex.

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Type-IInterferon-Inducible SERTAD3 Inhibits Influenza A Virus Replication by Blocking the Assembly of Viral RNA Polymerase Complex

Cell Reports ◽

10.1016/j.celrep.2020.108342 ◽

2020 ◽

Vol 33 (5) ◽

pp. 108342

Author(s):

Nina Sun ◽

Chunfeng Li ◽

Xiao-Feng Li ◽

Yong-Qiang Deng ◽

Tao Jiang ◽

...

Keyword(s):

Rna Polymerase ◽

Influenza A Virus ◽

Virus Replication ◽

Influenza A ◽

Viral Rna ◽

Polymerase Complex

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Genetic diversification of H5N1 highly pathogenic avian influenza A virus during replication in wild ducks

Journal of General Virology ◽

10.1099/vir.0.032623-0 ◽

2011 ◽

Vol 92 (9) ◽

pp. 2105-2110 ◽

Cited By ~ 17

Author(s):

Yohei Watanabe ◽

Madiha S. Ibrahim ◽

Hany F. Ellakany ◽

Hatem S. Abd El-Hamid ◽

Kazuyoshi Ikuta

Keyword(s):

Amino Acid ◽

Avian Influenza ◽

Influenza A Virus ◽

Influenza A ◽

Highly Pathogenic Avian Influenza ◽

Amino Acid Substitutions ◽

Highly Pathogenic ◽

Pathogenic Avian Influenza ◽

Novel Variants ◽

Avian Influenza A Virus

Highly pathogenic avian influenza A virus subtype H5N1 can potentially generate novel variants during replication of infected hosts. To determine which H5N1 variants predominate in wild birds, we determined the sequences of RT-PCR amplified viral genes from several organs of infected chickens and ducks from Egypt, where H5N1 outbreaks in birds are endemic. Comparison of the sequences in viruses from trachea, lung, brain and liver revealed diversification with different amino acid substitutions in different ducks, but no diversification in chickens. These specific amino acid substitutions were rare among viruses currently circulating in Egypt. In addition, the H5N1 variants showed distinct growth kinetics in duck, canine and human cells. Our findings suggested that ducks can generate H5N1 variants with novel amino acid substitutions that might serve as aetiological agents for new influenza virus outbreaks and epidemics.

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