Performance of the automated Abbott RealTime™ HIV-1 assay on a genetically diverse panel of specimens from Brazil

The combination of automated sample preparation and real-time RT-PCR for measurement of HIV-1 viral load has the potential to significantly enhance throughput, reduce operator-associated error, and increase assay sensitivity and dynamic range. In this study, RNA was extracted from the plasma of 91 HIV-1 seropositive Brazilian blood donors using the Abbott m2000sp™ automated sample preparation system. Viral loads measured using the RealTime™ HIV-1 (RealTime HIV-1) assay and the Abbott m2000rt™ instrument were compared to values obtained in the LCx® HIV RNA quantitative assay. Subtype was determined for 89 of 91 specimens by sequence/phylogenetic analysis of three genomic regions: gag p24, pol integrase, and env gp41. The panel included 69 subtype B, 1 C, 2 F, and 17 recombinant strains. Eighty-seven specimens were quantified by both assays. Two specimens were quantified only in RealTime HIV-1. Two additional specimens below the detection limit of both assays were also negative on PCR amplification. Viral load results were highly correlated, and good agreement was observed between assays with 90% of values within 0.5 log10 copies/ml. The RealTime HIV-1 assay and m2000 system offer the advantages of automation while providing reliable quantification of diverse HIV strains.