Using Exclusion-Based Sample Preparation (ESP) to Reduce Viral Load Assay Cost

Scott M Berry,David J Guckenberger,Eram D Williams,Franklin M Graziano,Jennifer M Loeb,Alex J Lavanway,Alice A Puchalski,David J Beebe,Hannah M Pezzi,Peter N Mugyenyi,Cissy M Kityo,Jean-Luc Eph Darlix

doi:10.1371/journal.pone.0143631

Scott M Berry, David J Guckenberger + Show 10 more

Open Access

https://doi.org/10.1371/journal.pone.0143631

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Abstract

Viral load (VL) measurements are critical to the proper management of HIV in developing countries. However, access to VL assays is limited by the high cost and complexity of existing assays. While there is a need for low cost VL assays, performance must not be compromised. Thus, new assays must be validated on metrics of limit of detection (LOD), accuracy, and dynamic range. Patient plasma samples from the Joint Clinical Research Centre in Uganda were de-identified and measured using both an existing VL assay (Abbott RealTime HIV-1) and our assay, which combines low cost reagents with a simplified method of RNA isolation termed Exclusion-Based Sample Preparation (ESP).71 patient samples with VLs ranging from <40 to >3,000,000 copies/mL were used to compare the two methods. We demonstrated equivalent LOD (~50 copies/mL) and high accuracy (average difference between methods of 0.08 log, R2 = 0.97). Using expenditures from this trial, we estimate that the cost of the reagents and consumables for this assay to be approximately $5 USD. As cost is a significant barrier to implementation of VL testing, we anticipate that our assay will enhance access to this critical monitoring test in developing countries.

Highlights

The World Health Organization (WHO) guidelines for utilizing antiretroviral therapy (ART) in HIV infected individuals recommend initiating ART at a threshold CD4 count of 500 cells/ mm3 or at any CD4 count when various confounding clinical factors are present [1]
Many studies in adults and children initiating ART and living in low income countries report that the strategy of evaluating CD4 count and clinical status without viral load (VL) monitoring leads to unnoticed virologic failure [3]
A total of 71 HIV+ plasma patient samples were obtained from the Joint Clinical Research Centre (JCRC) and RNA was extracted using both Exclusion-Based Sample Preparation (ESP) and Abbott m2000sp sample preparation

Summary

Introduction

The World Health Organization (WHO) guidelines for utilizing antiretroviral therapy (ART) in HIV infected individuals recommend initiating ART at a threshold CD4 count of 500 cells/ mm or at any CD4 count when various confounding clinical factors are present [1]. It further strongly recommends HIV viral load (VL) measurement as the preferred method to monitor treatment once initiated [1,2]. Many studies in adults and children initiating ART and living in low income countries report that the strategy of evaluating CD4 count and clinical status without VL monitoring leads to unnoticed virologic failure [3].

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