Vaccination results in a rapid but transient increase in antibody titer to multiple blockade epitopes in multiple GII.4 strains.

<p>Serum samples were evaluated for ability to block binding of mouse mAbs to epitope (Epi) A or F in GII.4.1997 and GII.4.2006b using a BOB assay. Sigmoidal curves were fit to the mean percent control binding (percent of mouse mAb bound to VLP in the presence of serum pretreatment compared to the amount of mouse mAb bound in the absence of serum pretreatment), and the mean EC₅₀ titer (1/serum dilution) for BOB calculated. Dotted line marks 0.5 times the assay limit of detection. Error bars represent 95% confidence intervals. An asterisk indicates that the EC₅₀ titer is significantly different from that of day 0.