Finally, formation of retroviral DNA circles, promoted by components of the non-homologous end joining for the two–long terminal repeat (2LTR) circles [8], and the HR Mre11 for the one–long terminal repeat (1LTR) circles [4], could be considered the result of an anti-viral activity by these two DNA repair pathways, rather than merely infection byproducts. The gene discussed is MRE11; the disease is infection.