The HBoV4 cluster included 6 strains. The complete genome of 1 representative strain (NI-385) was obtained (GenBank accession number FJ973561). The NS1 protein of HBoV4 (NI-385) showed an average of 11% divergence with HBoV2 and 25%-27% divergence with HBoV1 or HBoV3 (Table 2) . For the VP1 protein, the relative divergences were reversed, with an average divergence of 8.5% with HBoV3, 9.5% with HBoV2, and 19% with HBoV1. NI-385, therefore, also appears to be a recombinant, with the 5 genes NS1 and NP1 closely related to HBoV2 (particularly genotype A) and the 3 VP1 gene slightly more similar to HBoV3 than HBoV2 (Table 2 ). According to the International Committee on Taxonomy of Viruses species demarcation criteria in the genus Bocavirus, members of different species must show 15% divergence in their nonstructural gene nucleotide sequences [37] . The genetic distance of NI-385 to its closest relatives in the NS1 gene (HBoV2A) was 10.8% (range, 6.8%-12.6%), indicating that NI-385 qualifies, pending International Committee on Taxonomy of Viruses review, as the prototype of a fourth HBoV species (HBoV4). A distant VP1 (partial) variant of HBoV4 was also detected in the United States (US-MN-964-05; Figure 1 ). To determine whether the latter variant represents a second HBoV4 genotype will require full genome sequencing.