Taro bacilliform virus (TaBV) has been classified as a putative badnavirus based on its non-enveloped, bacilliform virion morphology and transmission
by mealybugs. The complete nucleotide sequence of a Papua New Guinea isolate of TaBV has now been determined and comprises
7458 bp. The genome contains four open reading frames (ORFs) on the plus-strand that potentially encode proteins of 17, 16,
214 and 13 kDa. The size and organisation of TaBV ORFs 1–3 is similar to that of most other badnaviruses, while the location
of ORF 4 is similar to that of ORF 4 and ORF X of the atypical badnaviruses
Citrus yellow mosaic virus and
Cacao swollen shoot virus, respectively. The putative amino acid sequence of TaBV ORF 3 contained motifs that are conserved amongst badnavirus proteins
including aspartic protease, reverse transcriptase (RT) and ribonuclease H (RNase H). The highly conserved putative plant
tRNA
met-binding site was also present in the 935 bp intergenic region of TaBV. Phylogenetic analysis using the amino acid sequence
of ORF 3 showed that TaBV branched most closely to
Dioscorea bacilliform virus. These results confirm that TaBV is a pararetrovirus of the genus
Badnavirus, family
Caulimoviridae.
Current address: PANBIO Ltd, 116 Lutwyche Rd, Windsor, Brisbane, 4030, Australia.
Received October 7, 2002; accepted November 28, 2002
Published online March 3, 2003