To determine the efficiency of CXCR4-gRNA/Cas9 modification in providing protection to primary CD4+ T cells against HIV-1 infection, we infected the cells (containing modified CXCR4) with CXCR4-tropic HIV-1NL4-3 and cultured for 7 days. The gene discussed is CXCR4; the disease is HIV-1 infection.