The detection of mutant spectra within the viral quasispecies is critical for therapeutic management of
HIV-1 infections. Routine clinical application of ultrasensitive genotyping requires reproducibility and
concordance within and between laboratories. The goal of the study was to evaluate a new protocol on
HIV-1 drug resistance testing by 454 ultra-deep pyrosequencing (454-UDS) in an international multicenter
study. Sixteen blinded HIV-1 subtype B samples were provided for 454-UDS as both RNA and
cDNA with viral titers of 88,600–573,000 HIV-1 RNA copies/ml. Eight overlapping amplicons spanning
protease (PR) codons 10–99 and reverse transcriptase (RT) codons 1–251 were generated using molecular
barcoded primers. 454-UDS was performed using the 454 Life Sciences/Roche GS FLX platform. PR
and RT sequences were analyzed using 454 Life Sciences Amplicon Variant Analyzer (AVA) software.
Quantified variation data were analyzed for intra-laboratory reproducibility and inter-laboratory concordance.
Routine population sequencing was performed using the ViroSeq HIV-1 genotyping system.
Eleven laboratories and the reference laboratory 454 Life Sciences sequenced the HIV-1 sample set. Data
presented are derived from seven laboratories and the reference laboratory since severe study protocol
execution errors occurred in four laboratories leading to exclusion. The median sequencing depth across
all sites was 1364 reads per position (IQR = 809–2065). 100% of the ViroSeq-reported mutations were
also detected by 454-UDS. Minority HIV-1 drug resistance mutations, defined as HIV-1 drug resistance
mutations identified at frequencies of 1–25%, were only detected by 454-UDS. Analysis of 10 preselected