CD4 and HIV-1 infection: In our study, we performed transduction of shSUN2 for 3 days and then infected cells with HIV-1 for an additional 3 days, and found that SUN2 knockdown significantly elevated HIV-1 infection of human primary CD4+ T cells, without obviously changing T-cell activation status after the total 6-day incubation, by monitoring the surface expression of CD25 and HLA-DR.