ERVW-1 and systemic lupus erythematosus: The mouse strains commonly used as models for human systemic lupus erythematosus (SLE)—New Zealand Black (NZB), New Zealand White (NZW), and 129—have high gene expression and protein levels of non-ecotropic ERV (NEERV) envelope glycoprotein gp70, concomitant with nephritis.