Primary resistance among HIV1 positive patients naive to antiretroviral therapy

Abstract number: O234

Skoura L., Papoutsi A., Papadimitriou E., Kollaras P., Ntoutsos I., Nikolaidis P., Malisiovas N.

Objective: The aim of the study was to estimate the prevalence of genotypic resistance among HIV-1 positive patients naive to antiretroviral therapy, since primary resistance has emerged as a potential barrier to the successful antiretroviral therapy and a threat for further transmission of resistant variants.

Methods: 218 newly diagnosed cases, reported to the National AIDS Reference Laboratory of Northern Greece between 2006 and 2008, were included in the study. All the subjects had never been exposed to antiretroviral therapy. Genotypic resistance testing was performed at the time of diagnosis with a sequence-based assay (TRUGENE HIV-1 genotyping test) targeted at the protease region (codons 1 to 99) and RT region (codon 40 to 247) of the HIV-l genome.

Results: 21 of 218 patients (9.63%) harboured a virus with at least one mutation associated with phenotypic resistance; 1/218 with mutations associated with resistance to nucleoside reverse-transcriptase inhibitors (NRTIs), 17/218 to non-nucleoside reverse-transcriptase inhibitors (NNRTIs) and 3/218 to protease inhibitors (PI). Resistance to NRTIs was associated with the key mutation M184V, while resistance to NNRTIs was associated with Y181C and K103N mutations. Among mutations to PI, major resistance mutations L90M and D30N were found in three patients, whereas there was a high prevalence of accessory PI resistance mutations at positions 10, 20, 36 and 63.

Conclusion: Our data estimate the prevalence of primary resistance and mutations patterns among naive HIV patients, underlining the importance of genotypic resistance testing in HIV patients before starting treatment, especially when NNRTIs would be included in the initial antiretroviral therapy.