Fig. (4).

This genetic structure of the ERVWE1 locus contains a complete HERV-W, with its three genes gag, pol and env, together with the flanking LTRs. Whereas the gag and pol genes have been silenced by mutations, the env gene has been conserved by selection. The env gene promoter is contained within the HERV-W 5’LTR, with the relevant genetic sequence also conserved. There is an intron insert between the gag and 5’LTR. The upstream regulation of the env gene is complex, including the MaLR 5’LTR and the non-viral regulatory region delineated in the figure. (After Gimenez J. and Mallet F. [19])