Use of floxuridine to modulate the antiviral activity of zidovudine

Use of recombinant viruses to assess the pattern of early human immunodeficiency virus breakthrough infection in the presence of stavudine

A variety of cell lines were infected with replication-defective recombinant retroviruses in the presence of stavudine (d4T). Cells which were infected despite the presence of d4T were isolated and subjected to infection with other retroviruses [replication-competent human immunodeficiency virus (HIV), replication-defective HIV or replication-defective recombinant murine retroviruses]. Each of the host cell types tested had a small subset of cells that were infected with HIV or murine retroviruses in the presence of d4T. Some of these infected cells could be infected repeatedly at high efficiency in the presence of d4T. This phenotype of 'persistent refractoriness' to the antiviral effects of d4T could be overcome by the addition of 5-fluoro-2-deoxyuridine (floxuridine) to d4T. The d4T-floxuridine combination also had potent antiretroviral effects in primary blood mononuclear cells.

Characterization and use of a recombinant retroviral system for the analysis of drug resistant HIV

A recombinant retroviral system was used for the analysis of early HIV breakthrough infection in the presence of antiviral drugs. The use of replication-defective HIV allowed a quantitative analysis of a single cycle of infection. This report characterizes this recombinant HIV system and demonstrates it's validity in comparison to standard assays. It is demonstrated that the protease inhibitor XM323 inhibits both early and late events in the HIV life-cycle, while dextran sulphate inhibits only early events. In addition, it is shown that this system can be used for detecting and quantitating drug resistant HIV. Thus, the use of this system may provide both novel information about the stage of the viral life-cycle inhibited and a preliminary assessment of the mechanism(s) responsible for breakthrough infection in the presence of antiretroviral drugs.