Roo is a potential insect retrovirus described in the genome of the dipter Drososphila melanogaster (Kaminker et al. 2002, unpublished data). Roo belongs to the Bel clade (Copeland et al. 2005) within Branch 1 of the Bel/Pao family (Llorens et al. 2009).
The genome of this element is 9.1 Kb in size, including LTRs of 429 (5’ LTR) and 428 nts (3’ LTR). The internal region of Roo displays a single ORF encoding for gag, pol and env polyproteins. Interestingly, our analyses suggest that the env protein of Roo is more similar to those envs coded by Ty3/Gypsy errantiviruses than those of the Bel/Pao family. Although this indicate that Roo might be a putative recombinant between a Bel/Pao element and a Ty3/Gypsy retrovirus further evidence is required to clarify if such a feature is also common in other Roo copies.
Figure not to scale. If present, long terminal repeats (LTRs) have been highlighted in blue. Amino acid motifs noted with lines indicate the conserved residues in each protein domain, abbreviations below mean:
||DU or DUT=dUTPase
||TAV or IBMP=transactivator/viroplasmin or inclusion body matrix protein
||PBS=primer binding site
||ATF=aphid transmission factor
||VAP=virion associated protein