Viral DNA is enriched in dead cells from HIV-infected lymph nodes. Viable (V) and dead (D) cells were purified by density gradient centrifugation as described in Materials and Methods. HIV and β-globin DNA sequences were co-amplified by PCR in 1,000 cells from each population. Upper panels show ethidium bromide-stained amplification products separated in agarose gel. Comparison of the relative intensities of β-globin–specific and HIV-specific bands by densitometric scanning (lower panels) revealed that HIV genomes in the dead cell populations from patients 5 and 7 were, respectively, ∼5 and <30 times more abundant than in the corresponding viable populations.