Identification and molecular characterization of a single-stranded circular DNA virus with similarities to Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1.

A putative circular single-stranded DNA (ssDNA) virus was recovered from Hypericum japonicum collected in Vietnam. The viral isolate was tentatively named Hypericum japonicum-associated circular DNA virus (HJasCV). HJasCV shares 58.7-65.4% nucleotide sequence identity with Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1) and SsHADV-1-like viruses. Like this group of viruses, the genome of HJasCV (2 200 nt) has two large ORFs, one in the virion-sense and the other in the complementary-sense DNA. The proteins encoded in the virion-sense and complementary-sense ORFs share 39-46 % and 45-67 % amino acid sequence identity with the putative capsid and replication-associated proteins (Reps), respectively, of SsHADV-1 and SsHADV-1-like viruses. The putative Rep of HJasCV contains all of the motifs related to rolling-circle replication. Its 111-bp intergenic region (IR) contains a hairpin structure with a geminivirus-like nonanucleotide sequence, TAATGTTAT, at the apex of the loop. Phylogenetic analysis revealed that HJasCV forms a monophyletic clade with SsHADV-1 and SsHADV-1-like viruses.