A new affordable flow cytometry based method to measure HIV-1 viral load

Area of Science:

• Virology
• Immunology
• Biotechnology

Background:

• Commercially available HIV-1 viral load assays often fail to detect rare genotypes like subtypes O and N, and circulating recombinant forms (CRFs).
• These assays are expensive and require specialized equipment, limiting their accessibility in developing countries.
• There is a critical need for cost-effective and broadly detecting viral load assays for global HIV management.

Purpose of the Study:

• To develop and validate a novel, low-cost viral load assay for human immunodeficiency virus type 1 (HIV-1).
• To ensure the assay can detect and quantify diverse HIV-1 subtypes, including those prevalent in sub-Saharan Africa.
• To reduce the cost of viral load testing for improved accessibility in resource-limited settings.

Main Methods:

• Development of a flow cytometry-based assay utilizing DIG- and DNP-labeled forward primers and a BIO-labeled reverse primer.
• Amplification of the HIV-1-5'LTR region and an internal standard sequence using polymerase chain reaction (PCR).
• Detection of PCR products via antibody-coated microparticles and streptavidin-R-phycoerythrine labeling, followed by flow cytometric analysis.

Main Results:

• The primer system successfully recognized all tested HIV-1 subtypes, including subtypes O, N, and CRFs.
• The assay demonstrated high sensitivity, quantifying viral loads from 50 to over 1 x 10(6) copies per PCR.
• The cost per test was reduced to less than 12 US$, a significant decrease from the typical 50-100 US$ for existing tests.
• The assay allows for reproducible viral load measurements due to a co-amplified internal standard.

Conclusions:

• The developed flow cytometry-based assay overcomes limitations of current viral load tests by detecting all relevant HIV-1 subtypes with high sensitivity.
• The reduced cost and broad subtype detection make this assay a viable solution for HIV viral load monitoring in developing countries.
• This technology enables a complete HIV monitoring program, including CD4 T-cell count and viral load, using a single device.