Impact of HIV type 1 subtype variation on viral RNA quantitation

Area of Science:

• Virology
• Molecular Diagnostics
• Public Health

Background:

• Accurate human immunodeficiency virus type 1 (HIV-1) RNA quantification is crucial for patient management.
• Existing viral load assays may exhibit performance variability with different HIV-1 subtypes.

Purpose of the Study:

• To evaluate and compare the performance of three HIV-1 RNA quantitation methods: Amplicor HIV-1 MONITOR-1.0, NASBA, and Quantiplex HIV RNA 2.0 (branched DNA [bDNA]).
• To assess the impact of HIV-1 subtypes (A, Thai B [B'], and E) on assay performance.

Main Methods:

• Plasma specimens (N=60) from individuals infected with HIV-1 subtypes A, B', or E (N=20 each) were analyzed.
• Performance of Amplicor HIV-1 MONITOR-1.0, NASBA, and bDNA assays was evaluated based on quantifiability and correlation.

Main Results:

• The bDNA assay demonstrated higher quantifiability for subtype A and E specimens compared to MONITOR-1.0 and NASBA.
• Subtype B' specimens showed better correlation among assays, with minor differences near the lower limit of detection.
• The enhanced MONITOR assay (MONITOR-1.0+) with a new primer set improved RNA detection across all subtypes.

Conclusions:

• HIV-1 subtype variation significantly influences viral load quantitation accuracy across different methods.
• Regular evaluation and potential modification of quantitative assays are necessary for reliable detection of diverse HIV-1 strains.