A novel phenotypic drug susceptibility assay for human immunodeficiency virus type 1

Although combination antiretroviral therapy has resulted in a considerable improvement in the treatment of human immunodeficiency virus (HIV) type 1 ( HIV-1) infection, the emergence of resistant virus is a significant obstacl e to the effective management of HIV infection and AIDS. We have developed a novel phenotypic drug susceptibility assay that may be useful in guiding therapy and improving long-term suppression of HIV replication. Susceptibil ity to protease (PR) and reverse transcriptase (RT) inhibitors is measured by using resistance test vectors (RTVs) that contain a luciferase indicator gene and PR and RT sequences derived from HIV-1 in patient plasma. Cells a re transfected with RTV DNA, resulting in the production of virus particles that are used to infect target cells. Since RTVs are replication defective , luciferase activity is measured following a single round of replication. The assay has been automated to increase throughput and is completed in 8 t o 10 days. Test results may be useful in facilitating the selection of opti mal treatment regimens for patients who have failed prior therapy or drug-n aive patients infected with drug-resistant virus. In addition, the assay ca n be used to evaluate candidate drugs and assist in the development of new drugs that are active against resistant strains of HIV-1.