FORWARD MUTATION-RATE OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 IN A T-LYMPHOID-CELL LINE

An in vivo assay was previously developed for detecting forward mutati ons in human immunodeficiency virus type 1 (HIV-1) in a single cycle o f replication, This system uses the lacZ alpha peptide gene as a repor ter for mutations, and allows for the rates and types of mutations tha t occur to be determined. The forward mutation rate for HIV-1 in HeLa cells was found to be 3 x 10(-5) mutations per target base pair per cy cle. To test whether the mutation rate was influenced by cell type, th e mutation rate of HIV-1 in GEM-A cells, a T lymphoid cell line, was d etermined, The mutation rate of HIV-I reverse transcription in CEM-A c ells was found to be 3 x 10(-5) mutations per target basepair per cycl e. The number and types of mutations observed were similar to that in HeLa cells, Specifically, base substitution mutations predominated, an d G-to-A transition mutations were the most common base substitution. G-to-A hypermutants were also characterized. The difference in HIV-1 m utation rate between HeLa and GEM-A cells was not significant, indicat ing that the accuracy of HIV-1 reverse transcription is comparable in both the HeLa and CEM-A cell lines.