The full-length VP2 genes of HBoV1-4 were used for viruslike particle (VLP) production in this study. HBoV1-3 VP2 genes were amplified from HBoV-positive stool specimens (111-BJ07, 211-BJ07, and 46-BJ07; GenBank accession numbers: JQ240469, JQ240470 and HM132056) [15] . HBoV1 is 1,629 bp (nt 3,373-5,001 according to HBoV1 strain ST1, GenBank accession number DQ000495), HBoV2 is 1,617 bp (nt 3,306-4,922 according to HBoV2 strain PK2255, GenBank accession number FJ170279), and HBoV3 is 1,620 bp (nt 3,410-5,029 according to HBoV3 strain W471, GenBank accession number EU918736) in length. The VP2 genes of HBoV4 (1626 bp in length, nt3331-4956 based on HBoV4 strain NI-385, GenBank accession number NC012729) were synthesized by Sangon Biotech (Shanghai, China). These genes were verified by phylogenetic analysis using the Clustal W and MegAlign programs in the MEGA 4.0 software package [36] . The phylogenetic tree with 1,000 bootstrap replicates was generated based on the complete sequences of the VP2 genes used in this study and reference sequences from GenBank. HBoV1 strains ST1, ST2, and TW2888_06; HBoV2 strains W153, PK-2255, LZ55602, and 277-BJ07; HBoV3 strains W471 and W855; and HBoV4 strains NI-385 were used as reference sequences (GenBank accession numbers DQ000495, DQ000496, EU984237, EU082213, FJ170279, GU301645, JQ240471, EU918736, FJ948861, NC012729, respectively). 