The genomic organization of HBoV species are remarkably similar to those of animal bocaviruses, except that all HBoV NS ORFs encode a shorter NS2 protein (630-650 amino acids), compared with the longer NS1 of animal bocaviruses (716-726 amino acids) ( Figure 5A ). We noticed in all 4 HBoV species the presence of a stretch of encoded amino acids similar to the C-terminus of the longer NS1 of animal bocaviruses overlapping the NP ORF, but in a different frame ( Figure 5A) . Genomes of all HBoV species were aligned to determine the presence of conserved potential RNA splicing signals near the end of the smaller NS2 ORF and the putative second exon encoding the C-terminal region of NS1 (Figure 5B). The putative NS1 resulting from such a spliced transcript encoded a 750-780 amino acid protein with a carboxy terminus that showed significant similarity to that of the canine and bovine bocaviruses NS1 ( Figure 5C ) [39, 40] . A study using RT-PCR for the detection of HBoV1 viral transcript in human lung epithelial cells did not detect the NS splicing proposed here [41] . On the other hand, the proposed NS1 RNA splicing and NS1 protein expression itself were detected using Northern blots and NS1 C-termini specific sera, respectively, in 293 and human epithelial cells transfected with plasmids expressing HBoV1 transcripts (Jianming Qiu, personal communication).