Nucleotide sequences of two circular single-stranded DNAs associated with banana bunchy top virus

Two circular single-stranded DNAs designated DNA I and II of the banana bunchy top virus (BBTV) genome were cloned and sequenced. The sequence of BBTV DNA I consisted of 1,106 nucleotides and contained four open reading frames (ORFs) potentially encoding proteins with molecular masses ranging from 5.4 to 33.18 kDa and one putative stemloop structure of 29 nucleotides. The sequence of BBTV DNA II had 1,096 nucleotides and contained four ORFs encoding putative proteins with sizes ranging from 5.6 to 32.77 kDa and one putative stem-loop structure of 32 nucleotides. The largest ORF (V2) in DNA II encoded a putative replicase with the nucleotide triphosphate-binding motif (GGEGKS). DNAs I and II had a 54.3% identity in total sequence and two conserved regions with more than 80% sequence identity. The two BBTV DNA sequences showed no close relationship with geminivirus DNA sequences but some similarity with the coconut foliar decay virus (CFDV) DNA sequence (about 39% identity). DNAs I and II showed considerable similarity with BBTV component 1, with 50.3 and 52.9% identity, respectively. The loop sequences of putative stem-loop structures in both BBTV DNAs were highly homologous and also had considerable similarity with those of geminivirus, CFDV DNAs, and BBTV component 1