At the same time, in HIV infection of its natural target cells, integration has been shown to be essential for productive HIV replication in primary blood CD4 T cells [13, 14, 17], transformed T cell lines [9, 11, 13], peripheral blood mononuclear cells (PBMC), and PBMC-derived macrophages [10, 12], similar to earlier observations of the requirement for viral integration in other retroviruses [1-3]. The gene discussed is CD4; the disease is HIV infectious disease.