Banana bunchy top virus DNA-2 to 6 are monocistronic

Banana bunchy top virus (BBTV) DNA-3 to 6 have each previously been shown to contain one large open reading frame in the virion sense, whereas no large ORF had been identified in BBTV DNA-2. RNAs transcribed from the BBTV genome were mapped using northern hybridisation and 3' RACE. One mRNA was transcribed from each of BBTV DNA-2 to 6 and four of these mRNAs mapped to the ORFs previously identified in BBTV DNA-3 to 6. The mRNA of BBTV DNA-2 was transcribed from a virion sense ORF probably using a TATA box sequence different to that in BBTV DNA-1, and DNA-3 to 6. This ORF encoded a 10 kDa protein of unknown function. The 3' untranslated region of the five mRNAs varied from 25 nucleotides (BBTV DNA-6) to 167 nucleotides (BBTV DNA-4) and each contained putative polyadenylation signals with associated GT rich sequences together with a possible termination signal (C/T/A)TGTAA conserved in all five mRNAs.