@article{4b888388791c4cd0afa8b20ef0ad2be0,
title = "Genotypic and phenotypic nevirapine resistance correlates with virological failure during salvage therapy including abacavir and nevirapine",
abstract = "OBJECTIVE: To study the development of resistance during 8 weeks of salvage therapy with abacavir and nevirapine in combination with other reverse transcriptase inhibitors (RTIs) and protease inhibitors (PIs). METHODS: Samples obtained at baseline and after 8 weeks of therapy from 16 heavily pretreated patients were analysed for genotypic and phenotypic resistance. Genotypic resistance was analysed in cell-associated DNA and plasma HIV-RNA using direct sequencing. Phenotypic resistance was analysed in a PBMC-based assay and in a recombinant virus assay. Plasma viral load was measured at baseline and after 2, 4 and 8 weeks of therapy. RESULTS: The majority of patients was genotypically and phenotypically resistant to lamivudine, abacavir, zidovudine and PIs, whereas 50% of the patients showed resistance to nevirapine at baseline in at least one of the methods used. After 8 weeks of salvage therapy, no additional development of resistance against nucleoside reverse transcriptase inhibitors and PIs could be detected. However, the amount of patients resistant to nevirapine increased to 83%. When the patients were divided into two groups according to baseline resistance against nevirapine, a significantly higher transient reduction in viral load was observed in patients with nevirapine-sensitive HIV at baseline compared to patients with resistant HIV at baseline. CONCLUSION: The transient effect of salvage therapy including abacavir and nevirapine was due to the effect of nevirapine. The lack of effect of abacavir was most likely due to cross-resistance between abacavir and lamivudine/zidovudine used in previous treatment.",
keywords = "Anti-HIV Agents, CD4 Lymphocyte Count, DNA, Viral, Dideoxynucleosides, Drug Resistance, Microbial, Drug Therapy, Combination, Genotype, HIV Infections, HIV-1, Humans, Molecular Sequence Data, Nevirapine, Phenotype, Polymerase Chain Reaction, Reverse Transcriptase Inhibitors, Salvage Therapy, Viral Load",
author = "J{\o}rgensen, {L B} and Katzenstein, {T L} and J Gerstoft and Mathiesen, {Lars Reinhardt} and C Pedersen and C Nielsen",
year = "2000",
language = "English",
volume = "5",
pages = "187--94",
journal = "Antiviral Therapy",
issn = "1359-6535",
publisher = "Sage Publications",
number = "3",
}