Koala Retrovirus (KoRV) is a C-type retrovirus detected by electron microscopy in mitogen-stimulated peripheral blood mononuclear cell cultures and lymphoma tissues (Hanger et al. 2000). Both complete and apparently truncated pro-retroviruses have been detected in DNA of clinically normal koalas and those with hemaetopoietic disease. Phylogenetically, KoRV belongs to the genus Gammaretrovirus, and is morphologically consistent with the mammalian C-type retroviruses. The genomic structure of KoRV is 8.4 Kb size including LTRs of 0.55 Kb. The internal region of this retrovirus displays a Primer Binding Site (PBS) complementary to a tRNAPro, Open Reading Frames (ORFs) for the gag, pol and env genes characteristic of retroviruses, and a Polypurine Tract (PPT) adjacent to the 3´LTR (Hanger et al. 2000).
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