Western blot analysis showed that the antisera against HBoV1, 2, 3, and 4 reacted with 400 ng of VLPs of each HBoV species, as indicated by detection of specific bands of 60 kD in size ( Figure 2A) . Similar cross-reactivities were also detected by ELISA assays ( Figure 2B ). Mouse sera against HBoV1, 2, 3, and 4 reacted strongly with the homologous VLPs. Moreover, all four antisera reacted with the heterologous HBoV VLPs when the concentration of the mice antiserum was high (.0.25 mg/mL). No significant reactivity was observed with the human parvovirus B19 VP2 or influenza virus H5 hemaglutinin (H5) antiserum ( Figure 2B ). These results are consistent with those reported by Kantola et al [22] .