Culture fluids of infected NP-2/CD4/CCR5 cells on day-seven, NP-2/CD4/CKR-L3 cells on day-42 and NP-2/CD4/CCR6 cells on day-52 were assayed for RT activities when CPE ascended at the level of 80-90% cell infection (Figure 2c). Here, CCR6 is linked to infection.