Division of Medical Virology, Department of Pathology, University of Cape Town and National Health Laboratory Service, Cape Town, South Africa.
Department of Haematology and Molecular Medicine, University of Witwatersrand and National Health Laboratory Service, Johannesburg, South Africa.
PLoS One. 2020 May 29;15(5):e0232345. doi: 10.1371/journal.pone.0232345. eCollection 2020.
In remote settings, timely plasma separation and transportation to testing laboratories is an impediment to the access of HIV viral load (VL) testing. Potential solutions are whole blood testing through point of care (POC) assays or dried blood spots (DBS).
We evaluated the performance of a prototype Alere q whole blood VL protocol and compared it against plasma (Abbott RealTime HIV-1) and DBS VL (Abbott RealTime HIV-1 DBS revised prototype protocol and Roche CAP/CTM HIV-1 v2.0 DBS free virus elution protocol). Virological failure (VF) was defined at >1000 copies/ml.
Of 299 samples, Alere q correctly classified VF in 61% versus 87% by Abbott DBS and 76% by Roche FVE. Performance varied across plasma VL categories. Alere q showed 100% sensitivity. Below 1000 copies/ml of plasma, Alere q demonstrated over-quantification, with 19% specificity. Abbott DBS had 91% sensitivity and the best overall correlation with plasma (r2 = 0.72). Roche FVE had the best specificity of 99% but reduced sensitivity of 52%, especially between 1000-10,000 copies/ml of plasma. Correlation was best for all assays at >10,000 copies/ml.
Variability was prominent between the assays. Each method requires optimization to facilitate the implementation of a cut-off with optimal sensitivity and specificity for VF. Although Alere q whole blood assay exhibited excellent sensitivity, the poor specificity of only 19% would lead to unnecessary switching of regimens. Thus any VF detected would need to be confirmed by a more specific assay. Both the Abbott DBS and Roche FVE protocols showed good specificity, however sensitivity was reduced when the plasma VL was 1000-10,000 copies/ml. This could result in delays in detecting VF and accumulation of drug resistance. Field evaluation in settings that have adopted these DBS protocols are necessary.
在偏远地区，及时进行血浆分离并运输到检测实验室是 HIV 病毒载量 (VL) 检测的障碍。潜在的解决方案是通过即时护理 (POC) 检测或干血斑 (DBS) 进行全血检测。
我们评估了 Alere q 全血 VL 协议的原型性能，并将其与血浆 (Abbott RealTime HIV-1) 和 DBS VL (Abbott RealTime HIV-1 DBS 修订原型协议和 Roche CAP/CTM HIV-1 v2.0 DBS 免费病毒洗脱协议) 进行了比较。病毒学失败 (VF) 定义为 >1000 拷贝/ml。
在 299 个样本中，Alere q 在 61%的情况下正确分类 VF，而 Abbott DBS 在 87%的情况下正确分类，Roche FVE 在 76%的情况下正确分类。性能因血浆 VL 类别而异。Alere q 表现出 100%的灵敏度。在低于 1000 拷贝/ml 的血浆中，Alere q 表现出过度定量，特异性为 19%。Abbott DBS 的灵敏度为 91%，与血浆的相关性最好 (r2 = 0.72)。Roche FVE 的特异性最好，为 99%，但灵敏度降低，特别是在血浆为 1000-10000 拷贝/ml 之间时，灵敏度降低至 52%。所有检测方法在 >10000 拷贝/ml 时相关性最好。
检测方法之间存在明显的差异。每种方法都需要进行优化，以确定具有最佳灵敏度和特异性的 VF 截断值。虽然 Alere q 全血检测法表现出出色的灵敏度，但特异性仅为 19%，这将导致不必要的治疗方案转换。因此，任何检测到的 VF 都需要通过更具特异性的检测方法进行确认。Abbott DBS 和 Roche FVE 协议都显示出良好的特异性，但是当血浆 VL 为 1000-10000 拷贝/ml 时，灵敏度降低。这可能导致 VF 的检测延迟和耐药性的积累。在已经采用这些 DBS 协议的环境中进行现场评估是必要的。
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