As different HIV-1 and SIV proviruses were found to cleave human CARD8 after transfection in 293T cells (Figure 1 and Figure 2), we also tested a primary isolate of HIV-1 from a different clade and with a different co-receptor usage (HIV-1Q23-BG505, an R5, clade A recombinant virus) in an infection assay in WT and CARD8 KO THP-1 cells engineered to express the co-receptor CCR5 (Figure 3D). Here, CCR5 is linked to infection.