Nested PCR detection of viral DNA in HIV-infected immature DC. Culture day 8 sorted CD1a⁺ DC were exposed 1 day later to 500 TCID₅₀ of HIV-1_Ba-L or HIV-1_LAI. Relative HIV DNA content was assessed 48 hours PI by limiting dilutions of infected cell lysates in uninfected A301 cell lysates. DC that had been exposed to heat-inactivated (HI) virus were used as negative controls and assayed undiluted. β-Globin DNA level was assessed as amplification and DNA content control. The PCR sensitivity was 1 copy/3 × 10⁴ cells, as determined in parallel experiments by serial dilutions of 8E5/LAV cells (1 copy/cell) in HIV⁻ A301 parental cells (data not shown). Results of one of four experiments.