FIG. 1.

Assay system used for analysis of virus mutation frequencies. (A) Schematic representation of the HIV-1 vector used to analyze HIV-1 mutation frequencies. The proviral DNA form of the vector is shown. The large rectangular boxes are long terminal repeats, which include U3, R, and U5. The simian virus 40 promoter (SV40), luc gene, and luc gene start codon are indicated. (B) Single round of replication assay for mutation frequencies. Virus-producing cells were transfected with HIV-1 reporter vector and helper plasmids, and the viruses produced were concentrated and used to infect fresh MAGI cells. The MAGI assay and luciferase assay were used to determine the reverse mutation frequencies.