IgG antibody response in mice immunized with plasmid DNAs expressing chimeric HA.

<p>Mice (n = 4) were vaccinated with plasmid DNAs of chimeric HA, delivered by gene gun. Serum antibody (IgG) titers after third vaccination were evaluated by ELISA, with samples considered positive if their initial serum OD₄₀₅ was at least three times greater than the OD₄₀₅ of negative control sera. Samples with antibody titers below the detectable limit of the assay were assigned a titer of 50 for the purpose of generating graphs. Horizontal bars show mean values, and vertical error bars indicate standard deviation.