ERVs have been implicated in the pathogenesis of murine SLE, as early investigations revealed that the ERV-encoded Env protein gp70 was present in the sera of multiple lupus-prone and healthy mouse strains, but that only sera from SLE-prone mice contained anti-gp70 immune complexes (Izui et al., 1979). This evidence concerns the gene EMB and systemic lupus erythematosus.