We found that CD8 T cells could still inhibit R5 HIV infection in ALVAC-specific CD4 T cells even in the absence of direct cell contact (p24% for CD8- vs. trans-well CD8+: 11.1% vs. 5.1%) (Fig 8C), indicating that soluble HIV suppressive factors may play a role in this process. Here, CD4 is linked to HIV infectious disease.