CD4 and infection: Like in HeLa-CD4 cells, a significant decrease in virus infectivity measured in a single-round infection assay in target Jurkat cells was observed only when viruses were produced in UNG2- and RPA32-depleted cells (Fig. 3f), confirming that incorporation of UNG2 and RPA32 into viral particles is required for maintaining full HIV-1 infectivity in a single-round assay (7).