Ethidium bromide–stained agarose gel of HCV-amplified products after nested-PCR of PBMC and PBMC subsets of 3 patients (A, B, C, respectively) before and after mitogenic stimulation of cells. Lanes 1 through 3, PBMC at day 0, 7, 14 of stimulation; lanes 4 and 5, B lymphocytes at day 0, 7; lanes 6 through 8 and lanes 9 through 11, CD4⁺ and CD8⁺ cells at day 0, 7, 14 of stimulation, respectively. Day 0 corresponds to unstimulated cells. N, negative controls (serum samples from healthy blood donors); P, positive controls (serum samples with a known amount of HCV-RNA); M, DNA size markers.