FIG. 1.

Primary lymphocyte entry and infection by prototype R5X4 strains. (A) PBL were incubated for 1 h with or without the CXCR4 blocker T22 (2.5 uM) and infected overnight with R5X4 HIV-1 prototypes 89.6 and DH12, the R5 prototype Bal, and the X4 prototype NL43. Cells were then washed and refed with or without the CXCR4 antagonist. Supernatant p24 antigen was determined at day 7 postinfection. (B) PBL were incubated for 1 h with the CXCR4 antagonist T22 (2.5 uM), the CCR5 antagonist M657 (1 uM), both in combination, or CD4-blocking MAb 19 (5 μg/ml) and then infected with prototype viruses. The R5 primary isolate BL-2 was included in this experiment as an additional control for CCR5-mediated entry. Two days after infection total cellular DNA was subjected to quantitative real-time PCR amplification with primer and probe sets specific for the HIV-1 LTR or the cellular gene GAPDH. Data are representative of four to eight experiments with cells from different donors.