CCR7 and HIV-1 infection: Based on the linear differentiation model of CD8+ T cells defined by the lineage markers CD45RA and CCR7, it has been proposed that chronic progressive HIV-1 infection is related to a maturation block from effector memory phenotype (EM, CD45RA−/CCR7−) to full effector phenotype (E, CD45RA+/CCR7−)[20], [27].