Truncation of CPSF6 at residue 358 (CPSF6-358), which removes the RS domain, or alteration of four positively charged amino acids (K547, R549, R559, and R561) in the RS domain to glutamic acid (CPSF6-4Glu) (Fig. 3A) leads to decreased nuclear localization of CPSF6 and restriction of WT HIV-1 infection at the step of nuclear entry (21, 33). This evidence concerns the gene CPSF6 and HIV-1 infection.