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Ryt-Hansen P, Pedersen AG, Larsen I, Kristensen CS, Krog JS, Wacheck S, Larsen LE. Substantial Antigenic Drift in the Hemagglutinin Protein of Swine Influenza A Viruses. Viruses 2020; 12:E248. [PMID: 32102230 PMCID: PMC7077184 DOI: 10.3390/v12020248] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 12/16/2022] Open
Abstract
The degree of antigenic drift in swine influenza A viruses (swIAV) has historically been regarded as minimal compared to that of human influenza A virus strains. However, as surveillance activities on swIAV have increased, more isolates have been characterized, revealing a high level of genetic and antigenic differences even within the same swIAV lineage. The objective of this study was to investigate the level of genetic drift in one enzootically infected swine herd over one year. Nasal swabs were collected monthly from sows (n = 4) and piglets (n = 40) in the farrowing unit, and from weaners (n = 20) in the nursery. Virus from 1-4 animals were sequenced per month. Analyses of the sequences revealed that the hemagglutinin (HA) gene was the main target for genetic drift with a substitution rate of 7.6 × 10-3 substitutions/site/year and evidence of positive selection. The majority of the mutations occurred in the globular head of the HA protein and in antigenic sites. The phylogenetic tree of the HA sequences displayed a pectinate typology, where only a single lineage persists and forms the ancestor for subsequent lineages. This was most likely caused by repeated selection of a single immune-escape variant, which subsequently became the founder of the next wave of infections.
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Affiliation(s)
- Pia Ryt-Hansen
- National Veterinary Institute, Technical University of Denmark, Kemitorvet Building 204, DK-2800 Kongens Lyngby, Denmark
- Dpt. of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 2, DK-1870 Frederiksberg C, Denmark; (I.L.); (L.E.L.)
| | - Anders Gorm Pedersen
- Department of Health Technology, Section for Bioinformatics, Technical University of Denmark, Kemitorvet Building 208, DK-2800 Kongens Lyngby, Denmark;
| | - Inge Larsen
- Dpt. of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 2, DK-1870 Frederiksberg C, Denmark; (I.L.); (L.E.L.)
| | | | - Jesper Schak Krog
- Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark;
| | - Silke Wacheck
- Ceva Santé Animale 10 Avenue de la Ballastière, 33500 Libourne, France;
| | - Lars Erik Larsen
- Dpt. of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 2, DK-1870 Frederiksberg C, Denmark; (I.L.); (L.E.L.)
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Yasugi M, Kubota-Koketsu R, Yamashita A, Kawashita N, Du A, Misaki R, Kuhara M, Boonsathorn N, Fujiyama K, Okuno Y, Nakaya T, Ikuta K. Emerging antigenic variants at the antigenic site Sb in pandemic A(H1N1)2009 influenza virus in Japan detected by a human monoclonal antibody. PLoS One 2013; 8:e77892. [PMID: 24147093 PMCID: PMC3797713 DOI: 10.1371/journal.pone.0077892] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 09/05/2013] [Indexed: 11/18/2022] Open
Abstract
The swine-origin pandemic A(H1N1)2009 virus, A(H1N1)pdm09, is still circulating in parts of the human population. To monitor variants that may escape from vaccination specificity, antigenic characterization of circulating viruses is important. In this study, a hybridoma clone producing human monoclonal antibody against A(H1N1)pdm09, designated 5E4, was prepared using peripheral lymphocytes from a vaccinated volunteer. The 5E4 showed viral neutralization activity and inhibited hemagglutination. 5E4 escape mutants harbored amino acid substitutions (A189T and D190E) in the hemagglutinin (HA) protein, suggesting that 5E4 recognized the antigenic site Sb in the HA protein. To study the diversity of Sb in A(H1N1)pdm09, 58 viral isolates were obtained during the 2009/10 and 2010/11 winter seasons in Osaka, Japan. Hemagglutination-inhibition titers were significantly reduced against 5E4 in the 2010/11 compared with the 2009/10 samples. Viral neutralizing titers were also significantly decreased in the 2010/11 samples. By contrast, isolated samples reacted well to ferret anti-A(H1N1)pdm09 serum from both seasons. Nonsynonymous substitution rates revealed that the variant Sb and Ca2 sequences were being positively selected between 2009/10 and 2010/11. In 7,415 HA protein sequences derived from GenBank, variants in the antigenic sites Sa and Sb increased significantly worldwide from 2009 to 2013. These results indicate that the antigenic variants in Sb are likely to be in global circulation currently.
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Affiliation(s)
- Mayo Yasugi
- Department of Virology, Research Institute for Microbial Diseases (RIMD), Osaka University, Suita, Osaka, Japan
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
| | - Ritsuko Kubota-Koketsu
- Department of Virology, Research Institute for Microbial Diseases (RIMD), Osaka University, Suita, Osaka, Japan
- Kanonji Institute, The Research Foundation for Microbial Diseases of Osaka University, Kanonji, Kagawa, Japan
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
| | - Akifumi Yamashita
- Department of Genome Informatics, RIMD, Osaka University, Suita, Osaka, Japan
| | - Norihito Kawashita
- Department of Environmental Pharmacometrics, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka, Japan
| | - Anariwa Du
- Department of Virology, Research Institute for Microbial Diseases (RIMD), Osaka University, Suita, Osaka, Japan
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
| | - Ryo Misaki
- Applied Microbiology Laboratory, International Center of Biotechnology, Osaka University, Suita, Osaka, Japan
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
| | - Motoki Kuhara
- Ina Laboratory, Medical & Biological Laboratories Corporation, Ltd., Ina, Nagano, Japan
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
| | - Naphatsawan Boonsathorn
- Department of Medical Sciences, Ministry of Public Health, Muang, Nonthaburi, Thailand
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
| | - Kazuhito Fujiyama
- Applied Microbiology Laboratory, International Center of Biotechnology, Osaka University, Suita, Osaka, Japan
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
| | - Yoshinobu Okuno
- Kanonji Institute, The Research Foundation for Microbial Diseases of Osaka University, Kanonji, Kagawa, Japan
| | - Takaaki Nakaya
- International Research Center for Infectious Diseases, RIMD, Osaka University, Suita, Osaka, Japan
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
| | - Kazuyoshi Ikuta
- Department of Virology, Research Institute for Microbial Diseases (RIMD), Osaka University, Suita, Osaka, Japan
- The Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo, Japan
- * E-mail:
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