Delayed PHA induction of HIV-1–infected CD45RA⁺/CD4⁺ and CD45RO⁺/CD4⁺ cultures. Infected cultures were maintained in RPMI 1640, 10% human AB serum, and 50% LS. On days 4, 7, and 10 postinfection, aliquots of 10⁶ cells from each culture were removed and PHA-stimulated. After PHA stimulation, supernatants were collected every 2 days to determine RT activity, which is expressed as pixel values from PhosphorImager analysis.