The construction and characterization of a versatile bioassay for the quantification of HIV-1 viral infection and HIV-1 Tat protein activity based on recombinant adenoviral vectors carrying an HN LTR-driven luciferase reporter gene is described. The assay system consists of a set of two adeno-reporter vectors, one of which is responsive to HIV-1 Tat protein activity, and the second of which is not, by virtue of a deletion of the TAR site within the HIV LTR, This configuration of the reporter genes allows one to distinguish Tat-specific activation from Tat-non-specific HIV LTR-mediated gene expression. The adenoviral HIV LTR-mediated luciferase gene expression is highly responsive to Tat and increases linearly with increasing levels of HIV-1 infection, reaching levels of between 3- and 1000-fold induction. The adeno-reporter viruses can be utilized to detect Tat activity and HIV-1 infection in a wide range of cell types, including 293, CEM, HUT-78, Jurkat, and HeLa-derived cell lines. The resulting bioassay is convenient, sensitive, and readily adaptable to automated procedures, These characteristics of the adeno-reporter assay make it a valuable reagent for studies of HIV infection and for analysis of HIV-inhibitory agents.