CCR5 and infection: Advancements in utilizing ZFNs [245,246,247,248,249], TALENs [250,251], and CRISPR [252,253,254,255] for editing of the CCR5 gene have demonstrated that effective ablation of CCR5 expression in CD4+ T cells or hematopoietic stem and progenitor cells effectively protect these cells and their progeny from infection by CCR5-tropic (R5-tropic) HIV virus.