The titer of EV71 antibody in each of 5 groups of mice that received EV71 VLP (5μg), VLP (5μg) with alum, or phosphate-buffered saline (PBS) as a control according to immunization schedule as indicated by the arrows. (A) Titers of total IgG antibodies agains EV71 VLP were determined by ELISAs. (B) The titer of the neutralizing antibody against EV71 C4a was assayed by the titer of the serum in a microneutralization assay. The virus titer of EV71 C4a was 100 TCID50. (circle, wild type; square, VLP 5μg; triangle, VLP 5μg with alum). (C) Mice received EV71 VLP (5μg), VLP (5μg) with alum, or control and each titer was tested for cross-reactivity in mice against other EV71 subtypes by assaying the titer of the serum in a microneutralization assay. The virus titers of EV71 B3, B4, and C5 were each 100 TCID50, respectively (dot bar, EV71 B3 type; black bar, EV71 B4 type; white bar, EV71 C5 type; diagonal line bar, EV71 C4a). These data represent the means of two replicates and error bars indicate SD of the mean. Data statically analysis was performed by one way ANOVA, p < 0.01.