Document 0731
 DOCN  M94A0731
 TI    DdI susceptibility of HIV-1 isolates in patients on long-term therapy.
 DT    9412
 AU    Land S; McGavin C; Corby S; Tyssen D; Gorry P; Magliano D; Birch C;
       State HIV Isolation Laboratory, Virology Department, Fairfield;
       Hospital, Victoria.
 SO    Annu Conf Australas Soc HIV Med. 1993 Oct 28-30;5:107 (poster no. 64).
       Unique Identifier : AIDSLINE ASHM5/94348924
 AB    Sequential HIV isolates obtained from 18 individuals receiving
       dideoxyinosine (ddI) were tested for susceptibility to the drug. All
       patients had received AZI before commencing ddI therapy for up to 18
       months. Susceptibility assays were performed in peripheral blood
       lymphocytes infected with these isolates and maintained in 0.2 to 50
       microM of ddI. The dose of infectious virus was standardised for each
       assay. The mean 50% inhibitory concentration of 35 pre-therapy and 48
       post-therapy isolates was 3.4 microM (range, 0.1 microM to 12.5 microM)
       and 7.6 microM (range 0.1 microM to > 25 microM), respectively. Isolates
       from two patients showed greater than 10-fold increase in resistance to
       ddI after long term therapy. However, sequential isolates from the
       remaining patients showed no significant change in ddI susceptibility
       after up to 18 months of therapy. The emergence of HIV resistant to AZT
       occurs in about 50% of patients after 9 months of therapy. This
       contrasts with the development of ddI resistance which appears rarely or
       not at all after 18 months of therapy.
 DE    Cells, Cultured  Didanosine/*THERAPEUTIC USE  Dose-Response
       Relationship, Drug  Human  HIV Infections/*DRUG THERAPY/MICROBIOLOGY
       HIV-1/*DRUG EFFECTS  Long-Term Care  Lymphocytes/MICROBIOLOGY  Microbial
       Sensitivity Tests  MEETING ABSTRACT

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