Replicative capacity differences of thymidine analog resistance mutations in subtype B and C human immunodeficiency virus type 1.
In order to understand the impact of zidovudine resistance and thymidine analog mutations (TAMs) on subtype C human immunodeficiency virus type 1, we created mutants in subtype C reverse transcriptase (RT). The subtype B RT was placed in a subtype C backbone to act as a control. Mutants and wild-type (WT) virus were competed in a head-to-head competition assay to determine how different clones grew in the same culture. Different viruses were distinguished by sequence tags in nef and a quantitative-PCR assay. The 67N and 70R accessory mutations gave an advantage over the WT in subtype C, but these mutations in subtype B had replication capacities similar to that of the WT. Of the triple mutants examined, the TAM-1 types, 41L210W215Y, were the most fit in both subtypes, but only in subtype C was the replication capacity the same as that of the WT. The TAM-2 mutants, 67N70R215F, had the slowest replication in both clones. The mixed TAM pathway mutant, 67N70R215Y, in subtype C had a significant advantage over the TAM-2 mutant, but this was not seen in subtype B. When the WT viruses were competed with each other, the subtype B RT had enhanced replication relative to subtype C. The increased capacities of the 67N and 70R mutations may indicate that there will be greater transmitted resistance and persistence in a subtype C setting than what is known for subtype B.
Armstrong
Kimberly L
KL
Department of Immunology and Infectious Diseases and Harvard School of Public Health AIDS Initiative, Boston, Massachusetts 02115, USA.
Lee
Tun-Hou
TH
Essex
M
M
D002478:Cells, Cultured; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D015497:HIV-1 / Q000145:classification / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D009154:Mutation / Q000235:genetics; D012194:RNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism; D013936:Thymidine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects*
D012194:RNA-Directed DNA Polymerase; D013936:Thymidine