Mouse CD4 enhancer sequences, the human CD4 promoter, 8.8 kb of HIV sequences, and an SV40 polyadenylation signal was used for the transgene. The enhancer and promoter sequences were used to drive expression in CD4+ T cells and cells of the dendritic/macrophage lineage. The HIV sequence contained a stop oligo insertion at nucleotide 6400 of the env gene. Northern blot analysis showed high transgene expression in the thymus, moderate expression in lymph nodes, and weak expression in kidneys, lungs, intestines, and liver.