Representative standard curves for real-time PCR. In each PCR an internal standard curve from 20,000 infected cells to 2 infected cells was used. The standards were constructed by diluting HIVLAI chronically infected H9 cells into uninfected H9 cell DNA to maintain a constant level of DNA (equivalent to that from 20,000 cells). Each point is the mean, the error bars are 1 standard deviation, the solid line is the linear regression analysis, and the dashed curves are the 95% confidence intervals. Linear regression analysis was performed for minus-strand strong stop DNA (A) and completely synthesized HIV cDNA (B).