Replication of virus with PBS complementary to tRNAMet(e) or tRNAMet(i). Plasmids containing wild type or mutant proviral genomes were transfected into 293T cells. The virus was collected 48 hours later and the amount of infectivity determined using the JC53 assay. SupT1 cells were then infected with equal amounts of wild type or mutant viruses. The supernatant p24 measured at different times post infection. By day 21 and later, we recovered virus in which the PBS from HXB2-Met(e) had mutated to be complementary to tRNALys,3. The culture for HXB2-Met(i) was extended to over 200 days with no subsequent rise in p24 antigen. Key: squares (HXB2-WT); closed circles (HXB2-Met(e)); open circles HXB2-Met(i).