Development and evaluation of a national reference panel of HIV-1 protease and reverse transcriptase drug-resistance mutations for HIV-1 genotypic resistance assays in China.

Background: Transmission of antiretroviral drug-resistant strains of HIV-1 has a major impact on the success of HIV treatment regimens in most countries where antiretroviral therapy (ART) is available. It is now recommended that HIV-1 drug resistance be monitored in order to recommend appropriate therapy for infected ART-naïve individuals, or when choosing a new regimen for those patients not responding to ART. Commercial assays for the analysis of HIV-1 genotypic resistance have been approved by the US FDA. In China, several laboratories and research enterprises have been developing related assays, but at present, no systematic standardization or quality control for genotypic resistance assays has been established in China. A national reference panel is needed to evaluate and control the quality of HIV-1 genotype resistance assays in China.

Methods: A panel of five HIV-1 stocks (G1, G2, G3, G4, and G5) with well-characterized drug resistance was used to evaluate the resistance-mutation inclusivity of HIV-1 clades prevalent in China. Six samples (GS1-GS6) were used to evaluate the limit of detection (LOD) for the viral load levels, and five samples (GSS1-GSS3, GSS5, and GSS6) were used to evaluate the LOD for the percentages of mutant species within the range of detection. The samples were evaluated by five separate laboratories using one or two methods each, generating seven datasets in all.

Results: In samples G1-G5, which were used to evaluate inclusivity of HIV-1 clades, 92.86-100%, 16.67-83.33% and 4.17-8.33% of the most, intermediately, and least common resistance mutations, respectively, were reported by the seven datasets. For the LOD samples, four of the seven datasets reported correct resistance mutations in samples with minimal viral loads of >2 x 10(3) copies/mL, as well as in samples with >40% of mutants and viral loads of about 1 x 10(4) copies/mL; the other three tests did not amplify the target region or identify the mutants.

Conclusions: The results were quite variable between different tests. The panel of HIV-1 genotypic resistance could be used as a control for resistance testing in China.