Infection with non-B subtype HIV type 1 complicates management of established infection in adult patients and diagnosis of infection in newborn infants

Impact of human immunodeficiency virus type 1 (HIV-1) genetic diversity on performance of four commercial viral load assays: LCx HIV RNA Quantitative, AMPLICOR HIV-1 MONITOR v1.5, VERSANT HIV-1 RNA 3.0, and NucliSens HIV-1 QT

Human immunodeficiency virus type 1 (HIV-1) evolution and changing strain distribution present a challenge to nucleic acid-based assays. Reliable patient monitoring of viral loads requires the detection and accurate quantification of genetically diverse HIV-1. A panel of 97 HIV-1-seropositive plasma samples collected from Cameroon, Brazil, and South Africa was used to compare the performance of four commercially available HIV RNA quantitative tests: Abbott LCx HIV RNA Quantitative assay (LCx), Bayer Versant HIV-1 RNA 3.0 (bDNA), Roche AMPLICOR HIV-1 MONITOR v1.5 (Monitor v1.5), and bioMérieux NucliSens HIV-1 QT (NucliSens). The panel included group M, group O, and recombinant viruses based on sequence analysis of gag p24, pol integrase, and env gp41. The LCx HIV assay quantified viral RNA in 97 (100%) of the samples. In comparison, bDNA, Monitor v1.5, and NucliSens quantified viral RNA in 96.9%, 94.8%, and 88.6% of the samples, respectively. The two group O specimens were quantified only by the LCx HIV assay. Analysis of nucleotide mismatches at the primer/probe binding sites for Monitor v1.5, NucliSens, and LCx assays revealed that performance characteristics reflected differences in the level of genetic conservation within the target regions.

Multicenter Study of the LCx® HIV RNA Quantitative Assay – a New Competitive Reverse Transcriptase-PCR which Targets pol Genomic Region of HIV-1 for the Measurement of Type B, Non-Type B and Group O HIV-1 RNA

Performance characteristics of the Abbott LCx HIV RNA Quantitative Assay (LCx HIV) were established in a multicenter study comparing it with the manual (Amplicor v1.5) and automated (Cobas) ultra-sensitive Roche Amplicor HIV-1 Monitor v1.5, the Bayer Quantiplex HIV RNA 3.0 (bDNA v3.0), and the Organon NucliSens HIV QT 2.0 (NucliSens). Within-run precision of LCx HIV assessed in clinical specimens was SD log10 0.210 at approximately 50 copies/ml, and log10 0.133 at approximately 400 copies/ml. Total precision in a reconstituted type B HIV-1 RNA panel was SD log10 0.380 at 100 copies/ml, and SD log10 0.180 at 1000 copies/ml. Type B HIV-1 RNA sensitivity (1 ml input) assessed at a 50%, 75% and 95% detection rate ranged from 29 to 41, 54 to 75 and 94 to 176 copies/ml, respectively. Overall specificity in HIV seronegative individuals was 99.78%. Linear regression indicated close assay correlations and agreements for measurement of type B HIV-1 RNA. Pearson's correlations and (Log10LCx=aLog10x + b) linear regressions were 0.91 (y=0.892 Log10Amplicor + 0.595), 0.93 (y=0.827 Log10Cobas + 0.969), 0.93 (y=0.951 Log10bDNA + 0.550), and 0.79 (y=0.834 Log10NucliSens + 0.911). LCx HIV was least affected by the genetic variability of HIV-1. LCx HIV detected 99% of non-type B HIV-1 group M samples (subtypes A-G), Amplicor v1.5 detected 96%, and bDNA v3.0 detected 99%. The assays detected 10/11, 1/11 and 8/11, respectively of the HIV-1 group O samples. LCx HIV vs. Amplicor/bDNA Spearman's rank correlations for quantification of non-type B HIV-1 RNA were 0.76/0.84 (A), 0.93/0.93 (C), 0.73/0.99 (D), 0.86/0.98 (E), and 0.40/0.83 (group O). LCx HIV assays consistently detect and quantify type B, non-type B and group O HIV-1 RNA.