Cloning and sequence analysis of two banana bunchy top virus genomes in Hainan

The genome of Banana bunchy top virus (BBTV) consists of six segments of single-stranded DNA of approximately 1 kb in length. We identified and sequenced the complete genomes of two BBTV isolates, one with and one without satellite DNA, from Haikou, Hainan, China. The Haikou-2 isolate contains six genomic segments and an additional satellite DNA while the Haikou-4 isolate contains only six genomic segments. Typical of other babuviruses, each genomic segment encodes a single open reading frame and contains the highly conserved stem-loop and major common regions. Phylogenetic analysis of the two Haikou isolates together with existing sequence records in GenBank confirmed the grouping of BBTV into two large groups and further refined the geographical distribution of each group. To accommodate the changes in the BBTV geographical distribution, the two groups are proposed as the Southeast Asian group and the Pacific-Indian Oceans group. Both the Haikou-2 and Haikou-4 isolates belong to the newly proposed Southeast Asian group.