Gene therapy is one of several approaches that are being tested in the search for an effective anti-human immunodeficiency virus (HIV) treatment. In this strategy, a "protective" gene would be introduced into target cells, rendering them relatively resistance to the virus-induced cytopathicity. Tat and Rev are viral proteins essential for HIV gene expression. Tat increases viral gene transcription and Rev is responsible for the nuclear export of mRNA encoding structural viral proteins. A fusion protein (Trev) was constructed, joining Tat and Rev transdominant mutant gene sequences. Previously, we showed that Trev inhibits both Tat and Rev activities in Jurkat T cells. To determine whether Trev could inhibit HIV replication in primary cells, we transferred the trev gene to peripheral blood lymphocytes and challenged them with different HIV strains. Levels of HIV p24 antigen (Ag) were reduced 4- to 15-fold in cultures of Trev-CD4+ T cells infected with two HIV primary clinical isolates and were not detectable in cultures infected with HIV strains NL4-3 and SF2. In contrast, cultures of nontransduced CD4+ T cells infected with the same viruses had levels of HIV p24 Ag up to 10 ng/ml. Trev-transduced CD4+ T cells demonstrated increased survival following HIV challenge for the length of the experiments (30 days). We did not observe rapid emergence of Trev-resistant HIV in our cultures. Following HIV challenge, cell-associated Trev protein was increased, supporting the hypothesis that cells surviving Trev expression provided a cell survival advantage. This work showed that Trev was able to inhibit HIV replication in primary CD4+ T cells, and, therefore the trev gene could be a candidate for gene therapy against HIV.