1 research outputs found
Seasonal H1N1 2007 influenza virus infection is associated with elevated preâexposure antibody titers to the 2009 pandemic influenza A (H1N1) virus
AbstractThe new influenza strain detected in humans in April 2009 has caused the first influenza pandemic of the 21st century. A crossâreactive antibody response, in which antibodies against seasonal H1N1 viruses neutralized the 2009 pandemic influenza A (H1N1) virus (2009 pH1N1), was detected among individuals aged >60âyears. However, factors other than age associated with such a crossâreactive antibody response are poorly documented. Our objective was to examine factors potentially associated with elevated preâexposure viroâneutralization and hemagglutinationâinhibition antibody titers against the 2009 pH1N1. We also studied factors associated with antibody titers against the 2007 seasonal H1N1 virus. One hundred subjects participating in an influenza cohort were selected. Sera collected in 2008 were analysed using hemagglutination inhibition and viroâneutralization assays for the 2009 pH1N1 virus and the 2007 seasonal H1N1 virus. Viroâneutralization results were explored using a linear mixedâeffect model and hemagglutinationâinhibition results using linearâregression models for intervalâcensored data. Elevated antibody titers against 2009 pH1N1 were associated with seasonal 2007 H1N1 infection (viroâneutralization, pâ0.006; hemagglutinationâinhibition, pâ0.018). Elevated antibody titers were also associated with age in the viroâneutralization assay (pâ<0.0001). Seasonal 2007 H1N1 infection is an independent predictor of elevated preâexposure antibody titers against 2009 pH1N1 and may have contributed to lowering the burden of the 2009 pH1N1 pandemic