To produce antigens that can be used to evaluate the seroprevalence of HBoVs, the VP2 genes of HBoV1-4 were expressed in baculovirus to generate VLPs. The VP2 genes of HBoV1, HBoV2, and HBoV3 were amplified from stool samples by PCR. The sequences of these genes were verified by phylogenetic analysis ( Figure 1A ). The VP2 genes from respiratory and stool specimens were very similar in sequences. The HBoV1 strain 111-BJ07 used in this study clustered with the reference HBoV1 strain ST2 [1] , with homologies of 99.8%. The HBoV2 strain 211-BJ07 has 97.9% identity with the reference HBoV2 strain PK-2255 [7] . The HBoV3 strain 46-BJ07 has 99.6% identity with reference HBoV3 strain W471 [8] . As we did not find any HBoV4 positive samples, the VP2 gene of HBoV4 was synthesized according to the sequence of HBoV4 strain NI-385 [9] .