In this study, we evaluated the cross-reactivity of mouse antisera against HBoV1, 2, 3, and 4 VP2 with VP2 VLPs for four species of human bocaviruses. Considerable cross-reactivity was found among the four HBoV species. However, human IgG antibodies against HBoV did not cross react with human parvovirus B19 and PARV4. These findings are consistent with those of a previous report [22] , suggesting that to obtain accurate data of the seroprevalences of the different HBoV species, it is necessary to correct for cross-reactivity between the four HBoVs. Comparison of the VP2 protein sequences of HBoV1-4 revealed a high degree of similarity. These similarities may account for the cross-reactivity of these viruses, and should be confirmed through epitope analysis. Human parvovirus B19 and PARV4 have no antigen crossreactivity with HBoVs, suggesting that human parvovirus B19 and PARV4 antibodies do not interfere with the HBoV seroprevalence results. The specificity of human bocavirus VLP-based ELISA with human sera has also been demonstrated with human parvovirus B19 VP2 and PARV 4 VP2 by Kantola et al [22] .