More recently, IgG antibodies reacting with the full-length ERV3–1 envelope glycoprotein expressed on the target cell surface have been detected in sera from a fraction of juvenile-onset SLE patients, as well as patients with multisystem inflammatory syndrome in children (MIS-C) following SARS-CoV-2 infection (106). This evidence concerns the gene ERV3-1 and systemic lupus erythematosus.