Stalk-specific seroreactivity to subtype H1 influenza viruses induced by cHA immunizations.

<p>ELISA depicts the seroreactivity of twice and thrice intranasally or intramuscularly vaccinated mice (cohort II: cH6/1, cH5/1, +/- cH9/1) to a variety of subtype H1 influenza viruses including (A) A/Puerto Rico/8/34 which has a stalk domain homologous to the cHA immunogens. Seroreactivity to heterologous H1N1 subtype strains including (B) pH1N1 (A/Netherlands/602/2009) and two drifted seasonal isolates, (C) A/USSR/90/1977 and (D) A/Brisbane/59/2007, is also demonstrated by ELISA. Error bars represent the standard deviation for replicates of pooled serum samples. Animals receiving two administrations of poly(I:C) alone (Adjuvant Only) IN were not bled at this timepoint so no data (nd) were generated.