As shown in Fig. 1a, the response breadth as defined by the number of peptide pools able to raise positive HIV-specific CD8+ T cells was significantly higher in early chronic infection group than the primary infection group (ranged 5–16 peptide pools with the median at 12 for early chronic infection group and 1–17 peptide pools with the median at 10 for the primary infection group, p = 0.022), suggesting that the prolonged HIV-infection could stimulate the host immune system to recognize new antigenic peptide pools and thereby broaden the HIV-specific CD8+ T-cell responses. This evidence concerns the gene CD8A and infection.