The MxB mutant Δ1-25 lacks the first 25 amino acids and does not inhibit HIV-1 [11], K131M is defective in GTP binding yet capable of inhibiting HIV-1 infection [40], R455D and M574D are deficient in oligomerization and deficient in HIV-1 inhibition [14,15]. This evidence concerns the gene MX2 and HIV-1 infection.