RT Journal Article SR Electronic T1 Antigenic and Genetic Characteristics of Swine-Origin 2009 A(H1N1) Influenza Viruses Circulating in Humans JF Science JO Science FD American Association for the Advancement of Science SP 197 OP 201 DO 10.1126/science.1176225 VO 325 IS 5937 A1 Garten, Rebecca J. A1 Davis, C. Todd A1 Russell, Colin A. A1 Shu, Bo A1 Lindstrom, Stephen A1 Balish, Amanda A1 Sessions, Wendy M. A1 Xu, Xiyan A1 Skepner, Eugene A1 Deyde, Varough A1 Okomo-Adhiambo, Margaret A1 Gubareva, Larisa A1 Barnes, John A1 Smith, Catherine B. A1 Emery, Shannon L. A1 Hillman, Michael J. A1 Rivailler, Pierre A1 Smagala, James A1 de Graaf, Miranda A1 Burke, David F. A1 Fouchier, Ron A. M. A1 Pappas, Claudia A1 Alpuche-Aranda, Celia M. A1 López-Gatell, Hugo A1 Olivera, Hiram A1 López, Irma A1 Myers, Christopher A. A1 Faix, Dennis A1 Blair, Patrick J. A1 Yu, Cindy A1 Keene, Kimberly M. A1 Dotson, P. David A1 Boxrud, David A1 Sambol, Anthony R. A1 Abid, Syed H. A1 St. George, Kirsten A1 Bannerman, Tammy A1 Moore, Amanda L. A1 Stringer, David J. A1 Blevins, Patricia A1 Demmler-Harrison, Gail J. A1 Ginsberg, Michele A1 Kriner, Paula A1 Waterman, Steve A1 Smole, Sandra A1 Guevara, Hugo F. A1 Belongia, Edward A. A1 Clark, Patricia A. A1 Beatrice, Sara T. A1 Donis, Ruben A1 Katz, Jacqueline A1 Finelli, Lyn A1 Bridges, Carolyn B. A1 Shaw, Michael A1 Jernigan, Daniel B. A1 Uyeki, Timothy M. A1 Smith, Derek J. A1 Klimov, Alexander I. A1 Cox, Nancy J. YR 2009 UL http://science.sciencemag.org/content/325/5937/197.abstract AB Since its identification in April 2009, an A(H1N1) virus containing a unique combination of gene segments from both North American and Eurasian swine lineages has continued to circulate in humans. The lack of similarity between the 2009 A(H1N1) virus and its nearest relatives indicates that its gene segments have been circulating undetected for an extended period. Its low genetic diversity suggests that the introduction into humans was a single event or multiple events of similar viruses. Molecular markers predictive of adaptation to humans are not currently present in 2009 A(H1N1) viruses, suggesting that previously unrecognized molecular determinants could be responsible for the transmission among humans. Antigenically the viruses are homogeneous and similar to North American swine A(H1N1) viruses but distinct from seasonal human A(H1N1).