CD4 and infection: However the kinetics of HIV-1 uncoating appear to be cell type dependent [4], hence we have adapted the assay in CD4+ Jurkat T cells stably expressing an engineered form of the human TRIM5α protein fused with CypA at position S322 (T5Cyp) or a mutant version that does not bind to capsid and cannot restrict infection (H126Q) [60].