title: Human immunodeficiency virus type 1 phenotypes in children with advanced disease treated with long-term zalcitabine.
abstract: Baseline and posttreatment human immunodeficiency virus type 1 (HIV-1) isolates from 38 symptomatic, zidovudine-experienced HIV-1-infected children enrolled in a prospective trial of zalcitabine (dideoxycytidine) monotherapy (Pediatric AIDS Clinical Trials Group 138) were studied for the presence of syncytium-inducing (SI) phenotype and zalcitabine resistance. Twenty of the isolates were SI and 18 were non-SI (NSI) at baseline. After >44 weeks of zalcitabine treatment, the SI and NSI phenotypes were maintained in 16 and 17 patients, respectively. One patient had an NSI-to-SI phenotypic switch, while SI-to-NSI reversion occurred in 4 children (20%). Isolates from 30 of these patients were analyzed by in vitro drug susceptibility assay: Mean IC50 values were 0.14 microM at baseline and 0.18 microM following zalcitabine treatment. Only 1 child (3%) developed zalcitabine resistance. Knowledge of the low incidence of zalcitabine resistance and the switch from SI to NSI phenotype in some children may prove useful when selecting antiretroviral drugs to be used in combination.
authors.affiliation: Department of Pediatrics, University of California at San Diego, La Jolla 92093-0672, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Viani
authors.forename: I L
authors.initials: IL
authors.lastname: Smith
authors.forename: S A
authors.initials: SA
authors.lastname: Spector
mesh_terms: D000293:Adolescent; D019380:Anti-HIV Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004352:Drug Resistance, Microbial; D015658:HIV Infections / Q000188:drug therapy*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D007223:Infant; D010641:Phenotype; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use; D013997:Time Factors; D016047:Zalcitabine / Q000627:therapeutic use*
chemical_list: D019380:Anti-HIV Agents; D018894:Reverse Transcriptase Inhibitors; D016047:Zalcitabine