FIG. 2.
Ability of HIV-1 viral isolates to bind to epithelial cell lines. Monolayers of 2.5 × 105 Caco-2 or A431 cells were incubated with 1, 10, and 100 REV of an HIV-1 isolate. Cells were washed and lysed, and RNA was extracted. Real-time PCR was used to amplify RNA from a conserved HIV-1 LTR region, and the average cycle threshold ± standard error of the mean is graphed. These data represent results from at least two independent experiments performed in triplicate. All P values were determined with respect to a mixed-effects model of virus bound to epithelial cells. Binding of HIV-1 isolates to the A431 cell line are presented in the upper panels. HIV-1 isolates binding to the Caco-2 cell line are presented in the lower panels. Clade A (N20, N54); clade B (BaL, LAI, 143); clade C (G31, G58); CRF01-AE (078, CMU08). R5 (CCR5) and X4 (CXCR4) represent coreceptor usage by the virus.