In Vivo Testing of Anti-HIV Immunotoxins

The past several years have seen great optimism resulting from the deployment of highly active antiretroviral therapies for the treatment of HIV infection. Combinations of reverse transcriptase and protease inhibitors can induce suppression of viremia, reversal of immunodeficiency state, and remission from AIDS-associated illnesses. However, long-term compliance with these drug regimens is difficult because of complicated dosing schedules, cost, and drug toxicities. The development of drug-resistant HIV has also limited the effectiveness of antiviral therapies. The evolution of drug-resistant HIV is enhanced when patient compliance drops and HIV replicates in the presence of moderate concentrations of antiviral agents. Even in patients in whom there has been complete suppression of HIV replication for several years, there are persistent reservoirs of HIV-infected cells. Cessation of therapy, or even modification of the intensive drug regimens, results in the prompt reestablishment of HIV replication. Thus, despite the great improvements made in the treatment of AIDS, there is still a need for the development of new antiviral agents, particularly ones that have different modes of action than existing antivirals.