Primate lentiviruses (i.e., HIV-1, HIV-2 and SIVs) are dual receptor viruses that use both the primary CD4 receptor and a coreceptor (primarily CCR5, CXCR4 or both) and by virtue of their ability to infect myeloid lineage cells as well as CD4+ T cells, establish infection within the CNS within 2 weeks post infection. The gene discussed is CXCR4; the disease is infection.