FIG. 2.
Protocol for study of HIV-1 recombination. Individual cell clones containing a single copy of both HIV-gptHXB2 and HIV-c-puroNL4-3 were established. Upon induction by removal of tetracycline, vector virus was harvested and used to inoculate CD4-positive HeLaT4 target cells, which was followed by selection and isolation of target cell clones. Going from a provirus in a producer cell to a provirus in a target cell comprised a single cycle of virus replication. Proviruses in each target cell clone were further analyzed by PCR, the HTA, restriction enzyme digestion, and DNA sequencing in order to identify recombinants and crossover points.