Endogenous retrovirus in the context of "Lentivirus"

Koala retrovirus (KoRV) is a retrovirus that is present in many populations of koalas. It has been implicated as the agent of koala immune deficiency syndrome (KIDS), an AIDS-like immunodeficiency that leaves infected koalas more susceptible to infectious disease and cancers. The virus is thought to be a recently introduced exogenous virus that is also integrating into the koala germline genome (becoming endogenous). Thus the virus can transmit both horizontally (from animal to animal in the classic sense) and vertically (from parent to offspring as a gene). The horizontal modes of transmission are not well defined but are thought to require close contact.

Koala retrovirus was initially described as a novel endogenous retrovirus found within the koala genome and in tissues as free virions. Viral DNA sequence analysis showed intact open reading frames and pathogenic DNA motifs strongly suggesting that KoRV is an active replicating endogenous retrovirus that can also produce infectious virions. The analysis also showed that KoRV was closely related to the highly pathogenic gibbon ape leukemia virus (GALV).