Establishment of a novel CCR5 and CXCR4 expressing CD4+ cell line which is highly sensitive to HIV and suitable for high-throughput evaluation of CCR5 and CXCR4 antagonists

CCR5 and CXCR4 are the two main coreceptors essential for HIV entry. Therefore, these chemokine receptors have become important targets in the search for anti-HIV agents. Here, we describe the establishment of a novel CD4+ cell line, U87.CD4.CCR5.CXCR4, stably expressing both CCR5 and CXCR4 at the cell surface. In these cells, intracellular calcium signalling through both receptors can be measured in a single experiment upon the sequential addition of CXCR4- and CCR5-directed chemokines. The U87.CD4.CCR5.CXCR4 cell line reliably supported HIV-1 infection of diverse laboratory-adapted strains and primary isolates with varying coreceptor usage (R5, X4 and R5/X4) and allows to investigate the antiviral efficacy of combined CCR5 and CXCR4 blockade. The antiviral effects recorded in these cells with the CCR5 antagonist SCH-C and the CXCR4 antagonist AMD3100 were similar to those noted in the single CCR5- or CXCR4-transfected U87.CD4 cells. Furthermore, the combination of both inhibitors blocked the infection of all evaluated HIV-1 strains and isolates. Thus, the U87.CD4.CCR5.CXCR4 cell line should be useful in the evaluation of CCR5 and CXCR4 antagonists with therapeutic potential and combinations thereof.