HIV-susceptible prMCs can be isolated from the circulation of pregnant women. (A) PCR evidence of viral entry (SS cDNA) shows that circulating prMCs (≥ 83% total cells), isolated from late third-trimester HIV-negative pregnant women, are strongly susceptible to R5-tropic HIV_BAL but only marginally susceptible to X4-tropic HIV_Tybe in (B) PCR evidence that circulating prMCs isolated from HIV⁺ pregnant women at term harbor integrated (HIV) proviral cDNA. All experiments were performed a minimum of 3 times. All error bars represent standard deviation of the mean of replicate PCR reactions at each data point.