Immunogenicity of hemagglutinin T cell epitopes in influenz

The swine origin, 2009 H1N1 influenza virus caused the first pandemic of 21st century. Unlike earlier pandemic strains, 2009 H1N1 was milder in disease severity and self-limited. Atypical milder severity of 2009 H1N1 pandemic drew the attention of researchers towards investigating the role of pre-existing T cellular immunity. The source of the pre-existing CD4 T cellular immunity was hypothesized to be due to the epitopes conserved between seasonal flu and 2009 H1N1. To investigate pre-existing T cellular immunity to 2009 H1N1 from previous exposures to seasonal flu, I conducted a bioinformatics analysis that predicted that ∼50% of the T cell epitopes are conserved between seasonal H1N1 and 2009 H1N1 strains. Further, through in vitro analysis I was able to demonstrate pre-existing CD4 T cellular immunity in healthy adult donors to conserved HA CD4 T cell epitopes that can potentially elicit cross-protective immune responses to 2009 H1N1.