CD4 and HIV infectious disease: We found that compared to whole PBMC, depletion of CD8 T cells from ALVAC-stimulated PBMC led to considerable increase in both R5 and X4 HIV infection of ALVAC-specific CD4 T cells (R5 HIV for CD8+ and CD8-: 2% vs. 6%; X4 HIV for CD8+ and CD8-: 7.4% vs. 13.8%) (Fig 8A).