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J Clin Invest. doi:10.1172/JCI74374.
Copyright ? 2015, The American Society for Clinical Investigation.
Research Article
Preexisting human antibodies neutralize recently emerged H7N9 influenza strains
Carole J. Henry Dunand1, Paul E. Leon2,3, Kaval Kaur1,4, Gene S. Tan2, Nai-Ying Zheng1,Sarah Andrews1, Min Huang1, Xinyan Qu1, Yunping Huang1, Marlene Salgado-Ferrer1, Irvin Y. Ho1,William Taylor1, Rong Hai2, Jens Wrammert5, Rafi Ahmed5, Adolfo Garc?a-Sastre2,6,7, Peter Palese2,6,Florian Krammer2 and Patrick C. Wilson1,4
1Department of Medicine, Section of Rheumatology, Gwen Knapp Center for Lupus and Immunology Research, The University of Chicago, Chicago, Illinois, USA.
2Department of Microbiology and
3Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
4Committee on Immunology, The University of Chicago, Chicago, Illinois, USA.
5Emory Vaccine Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.
6Department of Medicine and
7Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
Address correspondence to: Patrick C. Wilson, The University of Chicago, BSLC/Jules F. Knapp Building, 924 East 57th street, R414, Chicago, Illinois 60637, USA. Phone: 773.702.9009; E-mail: wilsonp@uchicago.edu. Or to: Florian Krammer, Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA. Phone: 212.241.7318; E-mail: florian.krammer@mssm.edu.
Authorship note: Patrick C. Wilson and Florian Krammer contributed equally to this work.
Published February 17, 2015
Submitted: July 21, 2014; Accepted: January 6, 2015.
The emergence and seasonal persistence of pathogenic H7N9 influenza viruses in China have raised concerns about the pandemic potential of this strain, which, if realized, would have a substantial effect on global health and economies. H7N9 viruses are able to bind to human sialic acid receptors and are also able to develop resistance to neuraminidase inhibitors without a loss in fitness. It is not clear whether prior exposure to circulating human influenza viruses or influenza vaccination confers immunity to H7N9 strains. Here, we demonstrate that 3 of 83 H3 HA-reactive monoclonal antibodies generated by individuals that had previously undergone influenza A virus vaccination were able to neutralize H7N9 viruses and protect mice against homologous challenge. The H7N9-neutralizing antibodies bound to the HA stalk domain but exhibited a difference in their breadth of reactivity to different H7 influenza subtypes. Mapping viral escape mutations suggested that these antibodies bind at least two different epitopes on the stalk region. Together, these results indicate that these broadly neutralizing antibodies may contribute to the development of therapies against H7N9 strains and may also be effective against pathogenic H7 strains that emerge in the future.
Introduction
Influenza A viruses evade the human immune system by changing the antigenic regions of their surface glycoproteins using two mechanisms: antigenic drift (point mutations) and antigenic shift (gene segment reassortments) (1). Antigenic variation is further increased by divergent evolution, as influenza virus strains recirculate continually among different host reservoirs, especially humans and avian species. The HA glycoprotein is the main target of neutralizing antibodies and is composed of an immunodominant globular head domain and a stalk domain (2). HA subtypes are classified into two groups based on their antigenic properties: amino acid sequences and structural features (3). Group 2 influenza A viruses include the H3 subtype, which further contains the seasonal H3N2 human strains, and the H7 subtype, which contains highly pathogenic avian influenza A viruses (4). Previously, infections with H7 viruses, through exposure to poultry, generally resulted in uncomplicated influenza illness and/or mild conjunctivitis (demonstrated for H7N3), with only one fatal case observed during an outbreak in The Netherlands (H7N7) (5, 6). However in 2013, a novel influenza A virus (H7N9), the product of genetic reassortment of various avian strains, emerged in China. This virus, associated with a high frequency of fatal human disease, appeared to have a wide dispersion and the potential for human-to-human transmission (7?12). Although the virus received the most publicity in 2013 (a year with 153 cases), the H7N9 virus shows a seasonal pattern, with most infections occurring during the winter season. The incidence of infection continues to increase, with nearly twice as many new H7N9 infections (301 cases) reported in 2014, totaling 454 cases, according to the World Health Organization, as of July 2014. These cases occurred in 12 provinces of China, with imported cases in Malaysia and Taiwan. The incidence of H7N9 infection combined with its abilities to bind to human receptor orthologs and to develop resistance to neuraminidase inhibitors without fitness loss has raised concerns about the pandemic potential of the H7N9 virus (13?15). With H7 strains currently posing a threat to human health, it is important to determine whether there is cross-protection generated from group 2 influenza virus vaccinations. Over several years, we have generated human antibodies from plasmablasts of volunteers vaccinated with the seasonal influenza virus vaccine (refs. 16, 17, and our unpublished data). Because plasmablasts are activated during an ongoing immune response, this allows us to determine whether prior vaccination, especially with H3N2 strains, induced cross-reactive antibodies that neutralize H7 strains. Given the lack of a vaccine against novel H7 viruses, the isolation and characterization of monoclonal antibodies with neutralizing activity can direct vaccine design and also provide a therapeutic resource.
Results
Cross-reactive antibodies induced by past influenza A virus exposure react with novel pathogenic H7N9 strains. To identify H7-binding antibodies, we developed an antibody microarray technology that allows high-throughput screening for cross-reactivity to influenza HA proteins (Figure 1A). We selected 83 antibodies, from 28 individuals, that were previously detected as H3N2 reactive by ELISA and tested their reactivity to different H3 and H7 recombinant HAs. We report here that 6 of the 83 (7%) H3-reactive antibodies bind both the A/Shanghai/1/2013 (H7N9) and A/Anhui/1/2013 (H7N9) strains isolated from the first infected patients in China. These 6 antibodies were each from different individuals, thus 21% (6 of 28 individuals) of this cohort had evidence of H7 cross-reactive immunity. Since we screened an average of only 3 H3N2-reactive antibodies per subject, we predict that a higher percentage of people previously vaccinated with H3N2 strains are likely to have cross-reactive antibodies that bind to the novel H7N9 strains.
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Full text:
http://www.jci.org/articles/view/74374
Copyright ? 2015, The American Society for Clinical Investigation.
Research Article
Preexisting human antibodies neutralize recently emerged H7N9 influenza strains
Carole J. Henry Dunand1, Paul E. Leon2,3, Kaval Kaur1,4, Gene S. Tan2, Nai-Ying Zheng1,Sarah Andrews1, Min Huang1, Xinyan Qu1, Yunping Huang1, Marlene Salgado-Ferrer1, Irvin Y. Ho1,William Taylor1, Rong Hai2, Jens Wrammert5, Rafi Ahmed5, Adolfo Garc?a-Sastre2,6,7, Peter Palese2,6,Florian Krammer2 and Patrick C. Wilson1,4
1Department of Medicine, Section of Rheumatology, Gwen Knapp Center for Lupus and Immunology Research, The University of Chicago, Chicago, Illinois, USA.
2Department of Microbiology and
3Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
4Committee on Immunology, The University of Chicago, Chicago, Illinois, USA.
5Emory Vaccine Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.
6Department of Medicine and
7Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
Address correspondence to: Patrick C. Wilson, The University of Chicago, BSLC/Jules F. Knapp Building, 924 East 57th street, R414, Chicago, Illinois 60637, USA. Phone: 773.702.9009; E-mail: wilsonp@uchicago.edu. Or to: Florian Krammer, Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA. Phone: 212.241.7318; E-mail: florian.krammer@mssm.edu.
Authorship note: Patrick C. Wilson and Florian Krammer contributed equally to this work.
Published February 17, 2015
Submitted: July 21, 2014; Accepted: January 6, 2015.
The emergence and seasonal persistence of pathogenic H7N9 influenza viruses in China have raised concerns about the pandemic potential of this strain, which, if realized, would have a substantial effect on global health and economies. H7N9 viruses are able to bind to human sialic acid receptors and are also able to develop resistance to neuraminidase inhibitors without a loss in fitness. It is not clear whether prior exposure to circulating human influenza viruses or influenza vaccination confers immunity to H7N9 strains. Here, we demonstrate that 3 of 83 H3 HA-reactive monoclonal antibodies generated by individuals that had previously undergone influenza A virus vaccination were able to neutralize H7N9 viruses and protect mice against homologous challenge. The H7N9-neutralizing antibodies bound to the HA stalk domain but exhibited a difference in their breadth of reactivity to different H7 influenza subtypes. Mapping viral escape mutations suggested that these antibodies bind at least two different epitopes on the stalk region. Together, these results indicate that these broadly neutralizing antibodies may contribute to the development of therapies against H7N9 strains and may also be effective against pathogenic H7 strains that emerge in the future.
Introduction
Influenza A viruses evade the human immune system by changing the antigenic regions of their surface glycoproteins using two mechanisms: antigenic drift (point mutations) and antigenic shift (gene segment reassortments) (1). Antigenic variation is further increased by divergent evolution, as influenza virus strains recirculate continually among different host reservoirs, especially humans and avian species. The HA glycoprotein is the main target of neutralizing antibodies and is composed of an immunodominant globular head domain and a stalk domain (2). HA subtypes are classified into two groups based on their antigenic properties: amino acid sequences and structural features (3). Group 2 influenza A viruses include the H3 subtype, which further contains the seasonal H3N2 human strains, and the H7 subtype, which contains highly pathogenic avian influenza A viruses (4). Previously, infections with H7 viruses, through exposure to poultry, generally resulted in uncomplicated influenza illness and/or mild conjunctivitis (demonstrated for H7N3), with only one fatal case observed during an outbreak in The Netherlands (H7N7) (5, 6). However in 2013, a novel influenza A virus (H7N9), the product of genetic reassortment of various avian strains, emerged in China. This virus, associated with a high frequency of fatal human disease, appeared to have a wide dispersion and the potential for human-to-human transmission (7?12). Although the virus received the most publicity in 2013 (a year with 153 cases), the H7N9 virus shows a seasonal pattern, with most infections occurring during the winter season. The incidence of infection continues to increase, with nearly twice as many new H7N9 infections (301 cases) reported in 2014, totaling 454 cases, according to the World Health Organization, as of July 2014. These cases occurred in 12 provinces of China, with imported cases in Malaysia and Taiwan. The incidence of H7N9 infection combined with its abilities to bind to human receptor orthologs and to develop resistance to neuraminidase inhibitors without fitness loss has raised concerns about the pandemic potential of the H7N9 virus (13?15). With H7 strains currently posing a threat to human health, it is important to determine whether there is cross-protection generated from group 2 influenza virus vaccinations. Over several years, we have generated human antibodies from plasmablasts of volunteers vaccinated with the seasonal influenza virus vaccine (refs. 16, 17, and our unpublished data). Because plasmablasts are activated during an ongoing immune response, this allows us to determine whether prior vaccination, especially with H3N2 strains, induced cross-reactive antibodies that neutralize H7 strains. Given the lack of a vaccine against novel H7 viruses, the isolation and characterization of monoclonal antibodies with neutralizing activity can direct vaccine design and also provide a therapeutic resource.
Results
Cross-reactive antibodies induced by past influenza A virus exposure react with novel pathogenic H7N9 strains. To identify H7-binding antibodies, we developed an antibody microarray technology that allows high-throughput screening for cross-reactivity to influenza HA proteins (Figure 1A). We selected 83 antibodies, from 28 individuals, that were previously detected as H3N2 reactive by ELISA and tested their reactivity to different H3 and H7 recombinant HAs. We report here that 6 of the 83 (7%) H3-reactive antibodies bind both the A/Shanghai/1/2013 (H7N9) and A/Anhui/1/2013 (H7N9) strains isolated from the first infected patients in China. These 6 antibodies were each from different individuals, thus 21% (6 of 28 individuals) of this cohort had evidence of H7 cross-reactive immunity. Since we screened an average of only 3 H3N2-reactive antibodies per subject, we predict that a higher percentage of people previously vaccinated with H3N2 strains are likely to have cross-reactive antibodies that bind to the novel H7N9 strains.
...
Full text:
http://www.jci.org/articles/view/74374