AEGiS-12IAC: Blinded comparison between two commercial methods for the quantification of HIV-1 viral load in plasma. Influence of the HIV-1 subtype.

12th International AIDS Conference

Geneva, Switzerland - June 28-July 3, 1998

Blinded comparison between two commercial methods for the quantification of HIV-1 viral load in plasma. Influence of the HIV-1 subtype.

Int Conf AIDS 1998 Jun 28-Jul 3; 12:17 (abstract no. 11175)

Fay F, Campodonico M, Del Pino N, Gonzales E, Taborda M, Fay O;;; CTSP National University Rosario, Argentina.

OBJECTIVES: To compare two commercial methods for HIV-1 viral load quantification and to correlate the differences with the viral subtypes present in the sample population.

DESIGN: Prospective, blind study.

MATERIALS AND METHODS: Blood EDTA samples were obtained from 67 HIV-1 infected patients. Plasma HIV-1 viral load was blindly measured using Quantiplex b-DNA v.2.0 (Chiron) and NASBA (Organon). HIV-1 env-subtype was defined starting by PBMCs DNA, using Heteroduplex Mobility Assay (HMA).

RESULTS: HMA resulted in the classification of 45 samples (67.2%) in subtype B, 17 (25.3%) in subtype F, 1 (1.5%) mixed infection (B + F) and in 4 cases (6%) the subtype could not be determined. HIV-RNA was detected in 62 samples by NASBA (92.5%) and in 61 samples by b-DNA (91%). 2 samples were undetectable by both methods. 4 samples (2 B, 2 F) were undetectable by b-DNA and had detectable levels by NASBA (3.15-3.76 logs). 3 samples 2B, 1 F) were undetectable by NASBA and had detectable levels by b-DNA (3.34-3.76 logs). There were highly concordant results (< 0.5 logs difference) in 52% of the samples and highly discordant results (> 1 logs difference) in 19% of the samples. 11 out of 13 highly discordant results (851/6) had less than 4 logs in average. Comparing the mean RNA values, NASBA measured 0.21 logs more than b-DNA. Analyzing according to the subtype, in subtype B samples, NASBA measured 0.35 logs more than b-DNA (95% CI = 0.18:0.52). Conversely, in subtype F samples, b-DNA measured 0.23 logs more than NASBA (95% CI = 0.18:0.64).

CONCLUSIONS: Both methods were able to quantify most of the samples regardless the subtype present. However, NASBA measured higher RNA values for subtype B samples, contrary to b-DNA that tended to measure higher RNA values for subtype F samples. The larger differences between both methods were in low copy number samples, which must be taken into account when making treatment decisions based on baseline viral load values.

Keywords: AEGIS, HIV-1, Viral Load, HIV Infections, Self-Sustained Sequence Replication, HIV-1 Reverse Transcriptase, Human, methods, ICA12
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