Characterization of H5N1 Influenza Virus Variants with Hemagglutinin Mutations Isolated from Patients
ABSTRACT A change in viral hemagglutinin (HA) receptor binding specificity from α2,3- to α2,6-linked sialic acid is necessary for highly pathogenic avian influenza (AI) virus subtype H5N1 to become pandemic. However, details of the human-adaptive change in the H5N1 virus remain unknown. Our database...
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American Society for Microbiology
2015
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oai:doaj.org-article:64717397769a42a5b96f86cc8cd161be2021-11-15T15:41:34ZCharacterization of H5N1 Influenza Virus Variants with Hemagglutinin Mutations Isolated from Patients10.1128/mBio.00081-152150-7511https://doaj.org/article/64717397769a42a5b96f86cc8cd161be2015-05-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00081-15https://doaj.org/toc/2150-7511ABSTRACT A change in viral hemagglutinin (HA) receptor binding specificity from α2,3- to α2,6-linked sialic acid is necessary for highly pathogenic avian influenza (AI) virus subtype H5N1 to become pandemic. However, details of the human-adaptive change in the H5N1 virus remain unknown. Our database search of H5N1 clade 2.2.1 viruses circulating in Egypt identified multiple HA mutations that had been selected in infected patients. Using reverse genetics, we found that increases in both human receptor specificity and the HA pH threshold for membrane fusion were necessary to facilitate replication of the virus variants in human airway epithelia. Furthermore, variants with enhanced replication in human cells had decreased HA stability, apparently to compensate for the changes in viral receptor specificity and membrane fusion activity. Our findings showed that H5N1 viruses could rapidly adapt to growth in the human airway microenvironment by altering their HA properties in infected patients and provided new insights into the human-adaptive mechanisms of AI viruses. IMPORTANCE Circulation between bird and human hosts may allow H5N1 viruses to acquire amino acid changes that increase fitness for human infections. However, human-adaptive changes in H5N1 viruses have not been adequately investigated. In this study, we found that multiple HA mutations were actually selected in H5N1-infected patients and that H5N1 variants with some of these HA mutations had increased human-type receptor specificity and increased HA membrane fusion activity, both of which are advantageous for viral replication in human airway epithelia. Furthermore, HA mutants selected during viral replication in patients were likely to have less HA stability, apparently as a compensatory mechanism. These results begin to clarify the picture of the H5N1 human-adaptive mechanism.Yohei WatanabeYasuha AraiTomo DaidojiNorihito KawashitaMadiha S. IbrahimEmad El-Din M. El-GendyHiroaki HiramatsuRitsuko Kubota-KoketsuTatsuya TakagiTakeomi MurataKazuo TakahashiYoshinobu OkunoTakaaki NakayaYasuo SuzukiKazuyoshi IkutaAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 6, Iss 2 (2015) |
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Microbiology QR1-502 |
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Microbiology QR1-502 Yohei Watanabe Yasuha Arai Tomo Daidoji Norihito Kawashita Madiha S. Ibrahim Emad El-Din M. El-Gendy Hiroaki Hiramatsu Ritsuko Kubota-Koketsu Tatsuya Takagi Takeomi Murata Kazuo Takahashi Yoshinobu Okuno Takaaki Nakaya Yasuo Suzuki Kazuyoshi Ikuta Characterization of H5N1 Influenza Virus Variants with Hemagglutinin Mutations Isolated from Patients |
description |
ABSTRACT A change in viral hemagglutinin (HA) receptor binding specificity from α2,3- to α2,6-linked sialic acid is necessary for highly pathogenic avian influenza (AI) virus subtype H5N1 to become pandemic. However, details of the human-adaptive change in the H5N1 virus remain unknown. Our database search of H5N1 clade 2.2.1 viruses circulating in Egypt identified multiple HA mutations that had been selected in infected patients. Using reverse genetics, we found that increases in both human receptor specificity and the HA pH threshold for membrane fusion were necessary to facilitate replication of the virus variants in human airway epithelia. Furthermore, variants with enhanced replication in human cells had decreased HA stability, apparently to compensate for the changes in viral receptor specificity and membrane fusion activity. Our findings showed that H5N1 viruses could rapidly adapt to growth in the human airway microenvironment by altering their HA properties in infected patients and provided new insights into the human-adaptive mechanisms of AI viruses. IMPORTANCE Circulation between bird and human hosts may allow H5N1 viruses to acquire amino acid changes that increase fitness for human infections. However, human-adaptive changes in H5N1 viruses have not been adequately investigated. In this study, we found that multiple HA mutations were actually selected in H5N1-infected patients and that H5N1 variants with some of these HA mutations had increased human-type receptor specificity and increased HA membrane fusion activity, both of which are advantageous for viral replication in human airway epithelia. Furthermore, HA mutants selected during viral replication in patients were likely to have less HA stability, apparently as a compensatory mechanism. These results begin to clarify the picture of the H5N1 human-adaptive mechanism. |
format |
article |
author |
Yohei Watanabe Yasuha Arai Tomo Daidoji Norihito Kawashita Madiha S. Ibrahim Emad El-Din M. El-Gendy Hiroaki Hiramatsu Ritsuko Kubota-Koketsu Tatsuya Takagi Takeomi Murata Kazuo Takahashi Yoshinobu Okuno Takaaki Nakaya Yasuo Suzuki Kazuyoshi Ikuta |
author_facet |
Yohei Watanabe Yasuha Arai Tomo Daidoji Norihito Kawashita Madiha S. Ibrahim Emad El-Din M. El-Gendy Hiroaki Hiramatsu Ritsuko Kubota-Koketsu Tatsuya Takagi Takeomi Murata Kazuo Takahashi Yoshinobu Okuno Takaaki Nakaya Yasuo Suzuki Kazuyoshi Ikuta |
author_sort |
Yohei Watanabe |
title |
Characterization of H5N1 Influenza Virus Variants with Hemagglutinin Mutations Isolated from Patients |
title_short |
Characterization of H5N1 Influenza Virus Variants with Hemagglutinin Mutations Isolated from Patients |
title_full |
Characterization of H5N1 Influenza Virus Variants with Hemagglutinin Mutations Isolated from Patients |
title_fullStr |
Characterization of H5N1 Influenza Virus Variants with Hemagglutinin Mutations Isolated from Patients |
title_full_unstemmed |
Characterization of H5N1 Influenza Virus Variants with Hemagglutinin Mutations Isolated from Patients |
title_sort |
characterization of h5n1 influenza virus variants with hemagglutinin mutations isolated from patients |
publisher |
American Society for Microbiology |
publishDate |
2015 |
url |
https://doaj.org/article/64717397769a42a5b96f86cc8cd161be |
work_keys_str_mv |
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