Sharing of endogenous lentiviral gene fragments among leporid lineages separated for more than 12 million years.

Lentiviruses are causal agents of severe pathologies of a variety of mammals, including cattle and humans (e.g., AIDS and different types of lymphoma). While endogenous forms of lentivirus do not occur in these species, A. Katzourakis and coworkers (A. Katzourakis, M. Tristem, O. G. Pybus, and R. J. Gifford, Proc. Natl. Acad. Sci. USA 104:6261-6265, 2007) recently reported the presence in the genome of the European rabbit (Oryctolagus cuniculus) of multiple sequences defining a lentiviral subgroup elegantly referred to as RELIK (rabbit endogenous lentivirus type K). Sequence comparisons indicated that the RELIK ancestor may have integrated into the rabbit lineage more than 7 million years ago. We have substantiated this by producing sequence data certifying the sharing of RELIK sequences among leporid lineages that diverged some 12 million years ago.