Evolution of CD4-cell count (number of cells per microliter), viral load (log10 number of copies of RNA per milliliter) and resistance-related genotype of the RT gene for patients SW3 (A) and CHG (B) who harbored viruses with the T69S-SS mutation. The times of retrieval of the original samples included in the screening, SW3-10125 and CHG-4815, respectively, are indicated by the bold arrow. Patient CHG had been treated with zidovudine (ZDV) since December 1990. ddI, didanosine; 3TC, lamivudine; d4T, stavudine; IDV, indinavir; WT, wild type.