CCR5 and HIV infectious disease: This cellular chemokine receptor is required for infectivity of many HIV strains.[7–9] Soon after its role in HIV replication was elucidated, individuals were identified who were highly resistant to HIV infection and lacked functional CCR5 as the result of a 32-bp deletion in the CCR5 gene but were otherwise healthy.[10–12] This experiment of nature suggested that CCR5 inhibitors could be effectiv antiretroviral agents, and several CCR5 inhibitors are now under clinical trials.