A DNA primer associated with banana bunchy top virus.

Banana bunchy top virus (BBTV) genomic ssDNA is capable of complementary strand synthesis in vitro without the addition of exogenous primers. We have demonstrated that the self-priming of BBTV can be attributed to a population of endogenous primers which are bound to the genomic DNA within the virions. The primer molecules appeared to be composed entirely of DNA and are heterogeneous in size. The primers were cloned, sequenced and shown to map to a region within the major common region and extend 5' of this conserved region. These primers were found to be associated with multiple components of the genome and were capable of full-length complementary strand synthesis in vitro. Interestingly, most of the cloned primers appeared to be derived from BBTV DNA-5; no function has yet been determined for the putative protein of the large ORF within this component.