Heterogeneity of koala retrovirus isolates
Sayumi Shimode a,1, So Nakagawa b,1, Rokusuke Yoshikawa a, Takayuki Shojima a, Takayuki Miyazawa a,*
aLaboratory of Signal Transduction, Department of Cell Biology, Institute for Virus Research, Kyoto University, 53 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507, Japan
bDepartment of Molecular Life Science, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan
1These two authors have contributed equally to this study
Koala retrovirus (KoRV) is a gammaretrovirus which may induce immune suppression, leukemia and lymphoma in koalas. Currently three KoRV subgroups (A, B, and J) have been reported. Our phylogenetic analysis suggests that KoRV-B and KoRV-J should be classified as the same subgroup. In long terminal repeat (LTR), a KoRV-B isolate has four 17 bp tandem repeats named direct repeat (DR)-1, while a KoRV-J isolate (strain OJ-4) has three 37 bp tandem repeats named DR-2. We also found that the promoter activity of the KoRV-J strain OJ-4 is stronger than that of original KoRV-A, suggesting that KoRV-J may replicate more efficiently than KoRV-A.