Lyubov PopovaKenneth SmithAnn H. WestPatrick C. WilsonJudith A. JamesLinda F. ThompsonGillian M. Air2015-01-232016-03-302015-01-232016-03-302012-07-25Popova L, Smith K, West AH, Wilson PC, James JA, et al. (2012) Immunodominance of Antigenic Site B over Site A of Hemagglutinin of Recent H3N2 Influenza Viruses. PLoS ONE 7(7): e41895. doi:10.1371/journal.pone.0041895http://hdl.handle.net/11244/14077The authors thank Shelly Gulati for virus purification, Upma Gulati for initiating the escape mutant selections, JingQi Feng for E05 analysis with viruses, Jennifer Muther for expressing the human monoclonal antibodies and Dr. J. West for critical discussion of data.Conceived and designed the experiments: LP GMA. Performed the experiments: LP. Analyzed the data: LP AHW GMA. Contributed reagents/materials/analysis tools: LFT JAJ KS PCW. Wrote the paper: LP GMA. Obtained plasma samples: LFT JAJ. Characterized and purified monoclonal antibodies: PCW KS.H3N2 influenza viruses have now circulated in the human population for 43 years since the pandemic of 1968, accumulating sequence changes in the hemagglutinin (HA) and neuraminidase (NA) that are believed to be predominantly due to selection for escape from antibodies. Examination of mutations that persist and accumulate led to identification of antigenically significant mutations that are contained in five antigenic sites (A–E) mapped on to the H3 HA. In early H3N2 isolates, antigenic site A appeared to be dominant while in the 1990s site B seemed more important. To obtain experimental evidence for dominance of antigenic sites on modern H3 HAs, we have measured antibodies in plasma of human subjects who received the 2006–07 trivalent subunit influenza vaccine (H3 component A/Wisconsin/67/05) or the 2008–09 formulation (H3 component A/Uruguay/716/07). Plasmas were tested against expressed HA of Wisconsin-like influenza A/Oklahoma/309/06 and site-directed mutants in antigenic site A (NNES121-124ITEG, N126T, N133D, TSSS135-138GSNA, K140I, RSNNS142-146PGSG), and antigenic site B (HL156-157KS, KFK158-160GST, NDQI189-192QEQT, A196V). “Native ELISA” analysis and escape mutant selection with two human monoclonal antibodies demonstrated that antibody E05 binds to antigenic site A and 1_C02 binds to site B. We find that most individuals, after vaccination in seasons 2006–07 and/or 2008–09, showed dominance of antigenic site B recognition over antigenic site A. A minority showed dominance of site A in 2006 but these were reduced in 2008 when the vaccine virus had a site A mutation. A better understanding of immunodominance may allow prediction of future antigenic drift and assist in vaccine strain selection.en-USAttribution 3.0 United StatesPLOSPublic Library of ScienceOpen AccessOpen-AccessScienceMedicineBiologyResearchPeer-reviewInclusiveInterdisciplinaryAnte-disciplinaryPhysicsChemistryEngineeringResearch Article10.1371/journal.pone.0041895false