The IFN-inducible human myxovirus resistance protein B or 2 (MxB/Mx2), related but distinct from MxA, has been recently described as a restriction factor for HIV-1 infection by acting after the completion of the reverse transcription process but before proviral integration, likely through interaction with the capsid-cyclophilin A complex [44,45,98,99]. This evidence concerns the gene MX2 and HIV-1 infection.