Plasma RNA quantification and HIV-1 divergent strains

Area of Science:

• Virology
• Clinical Diagnostics
• Molecular Biology

Background:

• HIV-1 diversity, particularly non-B group M and group O strains, challenges accurate viral load quantification.
• Commercial HIV viral load assays have historically underestimated non-B variants and failed to detect group O strains.
• Previous assay versions showed improved non-B variant quantification but still lacked group O detection.

Purpose of the Study:

• To evaluate the performance of the new Abbott LCx HIV RNA Quantitative assay.
• To assess its ability to detect and quantify diverse HIV-1 group M and group O variants.
• To compare the LCx assay with existing commercial and real-time PCR methods.

Main Methods:

• The Abbott LCx HIV RNA Quantitative assay was used to test 133 group M samples (69 non-B variants) and 70 group O samples.
• Performance was compared against the Cobas Amplicor HIV-1 Monitor v1.5 test.
• Comparison also included a quantitative real-time polymerase chain reaction method using LightCycler technology.

Main Results:

• The LCx assay demonstrated similar quantification ranges and high linearity (r2 = 0.9582) with the Cobas test for group M samples.
• The LCx assay successfully quantified group O variants in 31 of 48 patients, showing moderate linearity (r2 = 0.6195) with the LightCycler assay.
• Both assays were sensitive, but moderate linearity for group O may be due to strain diversity and primer/probe regions.

Conclusions:

• The Abbott LCx HIV RNA Quantitative kit effectively quantifies diverse HIV-1 group M variants.
• The LCx assay demonstrates capability in quantifying HIV-1 group O variants, addressing a significant diagnostic gap.
• This new assay offers improved viral load measurement for a broader spectrum of HIV infections.