Gibbon ape leukaemia virus (GALV) was first isolated in the early 1970s after a number of gibbons that were housed at the SEATO medical research in Bangkok, Thailand, were diagnosed with lymphoid tumours including malignant lymphoma. It is a novel gamma retrovirus that has never been isolated from wild gibbons. It appears that GALV occurred as a result of a species jump from another as yet unidentified vertebrate host. The full sequence of GALV suggests that it is related loosely to murine leukaemia viruses and a number of rodent species from Southeast Asia have been suggested as possible hosts of the ancestor to GALV. However, no proviral sequence from any Southeast Asian vertebrate has been so far isolated which could be a candidate virus. More recently, two closely related viruses have been found in koalas and a native Australian rat, the grassland melomys (Melomys burtoni). These are koala retrovirus (KoRV) and Melomys burtoni retrovirus (MbRV). A number of theories have been published recently which endeavour to explain the origins of GALV and its relationship to other viruses including KoRV. Here, the history of GALV is documented and the strengths and weaknesses of current theories on the origin of this virus are discussed.
Part of the book: Primates