Abstract: Objective:To discuss the antiviral effect, the inhibitory effect on LINE-1 retrotransposon activity and the redection of interferon production signal pathway of restriction factor SAMHD1 of the primates,and to provide the basis for further study of the SAMHD1 of the primates. Methods:The U937 cells stably expressing the SAMHD1 of primates were established; the U937-control cells established with pLVX-puro were used as negative control group,and the U937-SAMHD1 cells stably expressing the SAMHD1 protein of the different primates were used as experimental groups; the cells were treated with PMA to induce cell differentiation. The virus infection rates of HIV-1 in the cells in various groups were determined by flow cytometry. The HEK293T cells transfected with the expression plasmid of SAMDH1 were used as control group, and the cells co-transfected with the SAMHD1 and HIV-2/SIV Vpx expression plasmids were used as experimental groups.The cells were obtained 48 h after transfection,and the expression levels of SAMHD1 protein were determined by Western blotting method. The intracellular location of SAMHD1 protein was determined by immunofluorescence.The HEK293T cells transfected with LINE-1-GFP report plasmid were used as control group, and the cells co-transfected with LINE-1-GFP and SAMHD1 expression plasmids were used as experimental groups. The rates of GFP positive cells(activity of SAMHD1 to LINE-1 transposon) were determined by flow cytometry. The HEK293T cells transfected with IFN-Luc report plasmid were used as control group,and the cells co-transfected with IFN-Luc and pSAMHD1 expression plasmids were used as experimental groups. The expression levels of luciferase in HEK293T cells were determined by chemiluminescence instrument. Results:Compared with negative control group, the virus infection rates of HIV-1 in experimental groups with stable expression of SAMHD1 in the primates were significantly decreased (P<0.01). Compared with control group, the expression levels of SAMHD1 protein of the primates in experimental groups were decreased(P<0.05 or P<0.01).The immunofluorescence results showed that the SAMHD1 protein of the primates was localized in the nucleus. Compared with control group, the rates of GFP positive cells (activity of SAMHD1 to LINE-1 transposon) in experimental groups were significantly decreased (P<0.05 or P<0.01). Compared with control group, the expression levels of luciferase in the HEK293T cells in experimental groups were significantly decreased(P<0.05). Conclusion:The SAMHD1 protein of the different primates can resist the HIV-1 infection, inhibit the LINE-1 retrotransposon and antagonize the IFN production by natural immune system.

Key words: primate, restriction factor, sterile alpha motif and HD domain containing protein-1, retrovirus, retrotransposon, Vpx