Document 0725
 DOCN  M94A0725
 TI    Mechanisms of AZT resistance in HIV isolates.
 DT    9412
 AU    Buchanan L; Tachedjian G; Birch C; NCHVR, Fairfield Hospital, Victoria.
 SO    Annu Conf Australas Soc HIV Med. 1993 Oct 28-30;5:110 (poster no. 70).
       Unique Identifier : AIDSLINE ASHM5/94348930
 AB    To investigate the susceptibility of the reverse transcriptase (RT) and
       ribonuclease H (RNase H) from AZT-sensitive (AZT-S) and AZT-resistant
       (AZT-R) HIV isolates to AZT-triphosphate (AZTTP) and AZT-monophosphate
       (AZTMP). METHODS--Isolates obtained from a patient before and after
       long-term AZT therapy were examined for susceptibility to AZT. RT and
       RNase H from these isolates were analysed in in vitro assays to
       determine their susceptibilities to AZITP and AZTMP respectively.
       RESULTS AND CONCLUSIONS--Amino acid changes occurring in the HIV RT
       after long-term AZT therapy result in phenotypic AZT resistance.
       However, altered susceptibility cannot be definitely associated with the
       effects of AZTTP on RT or AZTMP on RNase H using enzyme assays,
       suggesting that the assay procedures used are not optimal or that
       alternative mechanisms of action are operating for AZT.
 DE    Antiviral Agents/PHARMACOLOGY  Drug Resistance, Microbial/GENETICS
       Human  HIV/*DRUG EFFECTS  HIV Infections/*DRUG THERAPY  Long-Term Care
       Reverse Transcriptase/ANTAGONISTS & INHIB  Thymine
       Nucleotides/PHARMACOLOGY  Virus Cultivation  Zidovudine/ANALOGS &
       DERIVATIVES/PHARMACOLOGY/*THERAPEUTIC USE  MEETING ABSTRACT

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