Osvaldo is a putative fly-retrovirus characterized in Drosophila buzzatii that shows a high transposition rate in some strains of this organism, as well as in D. buzzatii and D. koepferae hybrids (Labrador and Fontdevila 1994;Pantazidis, Labrador and Fontdevila 1999). Osvaldo gives the name and belongs, along with other Ty3/Gypsy LTR retroelements, to Osvaldo clade (Malik and Eickbush 1999). The genomic structure of Osvaldo is 9.1 Kb size including LTRs of 1.2 Kb. The internal region of this retrovirus displays, adjacent to both the 3´ and 5´ LTRs, two Primer Binding Sites (PBS) complementary to a tRNALys, two Open Reading Frames (ORFs) for gag, and pol genes, and an env gene partially encoded in two ORFs interrupted by an intron (Pantazidis, Labrador and Fontdevila 1999). Osvaldo also displays, as other Ty3/Gypsy elements, a Polypurine Tract (PPT) adjacent to the 3′ LTR.
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