Delayed HIV-1 infection of CD4+ T lymphocytes from therapy-naive patients demonstrated by quantification of HIV-1 DNA copy numbers

Measuring the amount of HIV-1 DNA in infected cells is important to estimate the size of the viral reservoir in patients. However, the clinical impact of the intracellular viral DNA level remains unclear. The present study examines the clinical significance of the HIV-1 DNA level in peripheral CD4(+) T lymphocytes from 21 therapy-naive patients. HIV-1 DNA levels in purified peripheral CD4(+) T lymphocytes were measured by the real-time PCR method using the Roche LightCycler system that can detect 200 copies/10(6) cells. We detected intracellular HIV-1 DNA in 15 (71.4%) of 21 patients at levels ranging from 270 to 98,120 copies/10(6) CD4(+) cells, with a median of 2,220 copies/10(6) cells. We also found HIV-1 DNA that was below the detection limit in the remaining 6 patients, although 8,800-150,000 copies/ml of HIV-1 RNA were detected in plasma. Circular HIV-1 DNA was not detected in 5 of 6 cases, suggesting that reverse transcription in CD4(+) T lymphocytes of these cases was not active. Thus, delayed HIV-1 infection of CD4(+) T lymphocytes was demonstrated in these patients. The level of HIV-1 DNA in peripheral CD4(+) T lymphocytes indicates the clinical status of therapy-naive patients.