Antiviral Resistance and Correlates of Virologic Failure in the first Cohort of HIV-Infected Children Gaining Access to Structured Antiretroviral Therapy in Lima, Peru: A Cross-Sectional Analysis
Background: The impact of extended use of ART in developing countries has been enormous. A thorough
understanding of all factors contributing to the success of antiretroviral therapy is required. The current study aims to
investigate the value of cross-sectional drug resistance monitoring using DNA and RNA oligonucleotide ligation assays
(OLA) in treatment cohorts in low-resource settings. The study was conducted in the first cohort of children gaining
access to structured ART in Peru.
Methods: Between 2002–5, 46 eligible children started the standard regimen of AZT, 3TC and NFV Patients had a
median age of 5.6 years (range: 0.7-14y), a median viral load of 1.7·105 RNA/ml (range: 2.1·103 – 1.2·106), and a median
CD4-count of 232 cells/μL (range: 1–1591). Of these, 20 patients were classified as CDC clinical category C and 31/46 as
CDC immune category 3. At the time of cross-sectional analysis in 2005, adherence questionnaires were administered.
DNA OLAs and RNA OLAs were performed from frozen PBMC and plasma, RNA genotyping from dried blood spots.
Results: During the first year of ART, 44% of children experienced virologic failure, with an additional 9% failing by the
end of the second year. Virologic failure was significantly associated with the number of resistance mutations detected by
DNA-OLA (p < 0.001) during cross-sectional analysis, but also with low immunologic CDC-scores at baseline (p < 0.001).
Children who had been exposed to unsupervised short-term antiretrovirals before starting structured ART showed
significantly higher numbers of resistance mutations by DNA-OLA (p = 0.01). Detection of M184V (3TC resistance) by
RNA-OLA and DNA-OLA demonstrated a sensitivity of 0.93 and 0.86 and specificity of 0.67 and 0.7, respectively, for the
identification of virologic failure. The RT mutations N88D and L90M (NFV resistance) detected by DNA-OLA correlated
with virologic failure, whereas mutations at RT position 215 (AZT resistance) were not associated with virologic failure.
Conclusions: Advanced immunosuppression at baseline and previous exposures to unsupervised brief cycles of ART
significantly impaired treatment outcomes at a time when structured ART was finally introduced in his cohort. Brief
maternal exposures to with AZT +/− NVP for the prevention of mother-to-child transmission did not affect treatment
outcomes in this group of children. DNA-OLA from frozen PBMC provided a highly specific tool to detect archived drug
resistance. RNA consensus genotyping from dried blood spots and RNA-OLA fromplasma consistently detected drug
resistance mutations, but merely in association with virologic failur