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Amino Acids in Hemagglutinin Antigenic Site B Determine Antigenic and Receptor Binding Differences between A(H3N2)v and Ancestral Seasonal H3N2 Influenza Viruses. J Virol 2017; 91:JVI.01512-16. [PMID: 27807224 DOI: 10.1128/jvi.01512-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 10/15/2016] [Indexed: 01/03/2023] Open
Abstract
Influenza A H3N2 variant [A(H3N2)v] viruses, which have caused human infections in the United States in recent years, originated from human seasonal H3N2 viruses that were introduced into North American swine in the mid-1990s, but they are antigenically distinct from both the ancestral and current circulating H3N2 strains. A reference A(H3N2)v virus, A/Minnesota/11/2010 (MN/10), and a seasonal H3N2 strain, A/Beijing/32/1992 (BJ/92), were chosen to determine the molecular basis for the antigenic difference between A(H3N2)v and the ancestral viruses. Viruses containing wild-type and mutant MN/10 or BJ/92 hemagglutinins (HAs) were constructed and probed for reactivity with ferret antisera against MN/10 and BJ/92 in hemagglutination inhibition assays. Among the amino acids that differ between the MN/10 and BJ/92 HAs, those in antigenic site A had little impact on the antigenic phenotype. Within antigenic site B, mutations at residues 156, 158, 189, and 193 of MN/10 HA to those in BJ/92 switched the MN/10 antigenic phenotype to that of BJ/92. Mutations at residues 156, 157, 158, 189, and 193 of BJ/92 HA to amino acids present in MN/10 were necessary for BJ/92 to become antigenically similar to MN/10. The HA amino acid substitutions responsible for switching the antigenic phenotype also impacted HA binding to sialyl receptors that are usually present in the human respiratory tract. Our study demonstrates that antigenic site B residues play a critical role in determining both the unique antigenic phenotype and receptor specificity of A(H3N2)v viruses, a finding that may facilitate future surveillance and risk assessment of novel influenza viruses. IMPORTANCE Influenza A H3N2 variant [A(H3N2)v] viruses have caused hundreds of human infections in multiple states in the United States since 2009. Most cases have been children who had contact with swine in agricultural fairs. These viruses originated from human seasonal H3N2 viruses that were introduced into the U.S. swine population in the mid-1990s, but they are different from both these ancestral viruses and current circulating human seasonal H3N2 strains in terms of their antigenic characteristics as measured by hemagglutination inhibition (HI) assay. In this study, we identified amino acids in antigenic site B of the surface glycoprotein hemagglutinin (HA) that explain the antigenic difference between A(H3N2)v and the ancestral H3N2 strains. These amino acid mutations also alter binding to minor human-type glycans, suggesting that host adaptation may contribute to the selection of antigenically distinct H3N2 variants which pose a threat to public health.
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Bangaru S, Nieusma T, Kose N, Thornburg NJ, Finn JA, Kaplan BS, King HG, Singh V, Lampley RM, Sapparapu G, Cisneros A, Edwards KM, Slaughter JC, Edupuganti S, Lai L, Richt JA, Webby RJ, Ward AB, Crowe JE. Recognition of influenza H3N2 variant virus by human neutralizing antibodies. JCI Insight 2016; 1. [PMID: 27482543 DOI: 10.1172/jci.insight.86673] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Since 2011, over 300 human cases of infection, especially in exposed children, with the influenza A H3N2 variant (H3N2v) virus that circulates in swine in the US have been reported. The structural and genetic basis for the lack of protection against H3N2v induced by vaccines containing seasonal H3N2 antigens is poorly understood. We isolated 17 human monoclonal antibodies (mAbs) that neutralized H3N2v virus from subjects experimentally immunized with an H3N2v candidate vaccine. Six mAbs exhibited very potent neutralizing activity (IC50 < 200 ng/ml) against the H3N2v virus but not against current human H3N2 circulating strains. Fine epitope mapping and structural characterization of antigen-antibody complexes revealed that H3N2v specificity was attributable to amino acid polymorphisms in the 150-loop and the 190-helix antigenic sites on the hemagglutinin protein. H3N2v-specific antibodies also neutralized human H3N2 influenza strains naturally circulating between 1995 and 2005. These results reveal a high level of antigenic relatedness between the swine H3N2v virus and previously circulating human strains, consistent with the fact that early human H3 seasonal strains entered the porcine population in the 1990s and reentered the human population, where they had not been circulating, as H3N2v about a decade later. The data also explain the increased susceptibility to H3N2v viruses in young children, who lack prior exposure to human seasonal strains from the 1990s.
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Affiliation(s)
- Sandhya Bangaru
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Travis Nieusma
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Nurgun Kose
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Natalie J Thornburg
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jessica A Finn
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Bryan S Kaplan
- Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Hannah G King
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Vidisha Singh
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Rebecca M Lampley
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Gopal Sapparapu
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Alberto Cisneros
- Chemical and Physical Biology Program, Vanderbilt University University, Nashville, Tennessee, USA
| | - Kathryn M Edwards
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - James C Slaughter
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Srilatha Edupuganti
- The Hope Clinic of Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA; Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Lilin Lai
- The Hope Clinic of Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA; Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Juergen A Richt
- College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Richard J Webby
- Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - James E Crowe
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Gautret P, Gray GC, Charrel RN, Odezulu NG, Al-Tawfiq JA, Zumla A, Memish ZA. Emerging viral respiratory tract infections--environmental risk factors and transmission. THE LANCET. INFECTIOUS DISEASES 2014; 14:1113-1122. [PMID: 25189350 PMCID: PMC7106556 DOI: 10.1016/s1473-3099(14)70831-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The past decade has seen the emergence of several novel viruses that cause respiratory tract infections in human beings, including Middle East respiratory syndrome coronavirus (MERS-CoV) in Saudi Arabia, an H7N9 influenza A virus in eastern China, a swine-like influenza H3N2 variant virus in the USA, and a human adenovirus 14p1 also in the USA. MERS-CoV and H7N9 viruses are still a major worldwide public health concern. The pathogenesis and mode of transmission of MERS-CoV and H7N9 influenza A virus are poorly understood, making it more difficult to implement intervention and preventive measures. A united and coordinated global response is needed to tackle emerging viruses that can cause fatal respiratory tract infections and to fill major gaps in the understanding of the epidemiology and transmission dynamics of these viruses.
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Affiliation(s)
- Philippe Gautret
- Assistance Publique Hôpitaux de Marseille, CHU Nord, Pôle Infectieux, Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France; Aix Marseille Université, Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), Faculté de Médecine, Marseille, France.
| | - Gregory C Gray
- College of Public Health and Health Professions and Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
| | - Remi N Charrel
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR-D 190 "Emergence des Pathologies Virales" and IHU Méditerranée Infection, APHM Public Hospitals of Marseille, Marseille, France
| | - Nnanyelugo G Odezulu
- College of Public Health and Health Professions and Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
| | - Jaffar A Al-Tawfiq
- Johns Hopkins Aramco Healthcare, and Indiana University School of Medicine, Indiana, USA
| | - Alimuddin Zumla
- Center for Clinical Microbiology, Division of Infection and Immunity, University College London, and NIHR Biomedical Research Center, University College London Hospitals, London, UK
| | - Ziad A Memish
- WHO Collaborating Center for Mass Gathering Medicine Ministry of Health and Al-Faisal University, Riyadh, Saudi Arabia
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