In vivo prevalence of azidothymidine (AZT) resistance mutations in an AIDS patient before and after AZT therapy.
In order to examine the in vivo prevalence of AZT resistance mutations in AID patients after long-term therapy we amplified, by polymerase chain reaction (PCR), a 654 bp pol gene fragment from peripheral blood mononuclear cell DNA samples from a patient before, and 19 months after, the start of AZT therapy. PCR products from each sample were cloned and 9 clones from each sample were sequenced. Seven of 9 clones from the post-AZT sample, but none from the pre-AZT sample, contained an amino acid substitution (Thr215 to Tyr) requiring two nucleotide changes within the same codon (ACC to TAC). This change had previously been shown by Larder and Kemp (Science, 246:1155-1158, 1989) to correlate with partial AZT resistance of virus isolates. In colony hybridizations using synthetic oligonucleotides corresponding to the mutant and wild-type sequences, 22 of 22 clones from the pre-AZT sample hybridized only to the wild-type probe while 21 of 26 clones from the post-AZT sample hybridized only to the mutant. Clinically, this patient remains well, indicating that while Tyr215 may be the first amino acid substitution leading to resistance, it alone does not appear to have significantly influenced the clinical status of this patient.
Fitzgibbon
J E
JE
Department of Molecular Genetics and Microbiology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway 08854.
Howell
R M
RM
Schwartzer
T A
TA
Gocke
D J
DJ
Dubin
D T
DT
D000163:Acquired Immunodeficiency Syndrome / Q000188:drug therapy / Q000382:microbiology*; D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D004279:DNA, Viral / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D015751:Genes, pol; D006678:HIV / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D013997:Time Factors; D015215:Zidovudine / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use
D004279:DNA, Viral; D015215:Zidovudine