Quantification Of The Hiv-1 Total Reservoir In The Peripheral Blood Of Naive And Treated Patients By A Standardised Method Derived From A Commercial Hiv-1 Rna Quantification Assay

Objectives: HIV-1 DNA can persist in host cells, establishing a latent reservoir. This study was aimed to develop an extraction and amplification protocol for HIV-1 DNA quantification by modifying a quantitative commercial assay.Methods: HIV-1 DNA was extracted on an Abbott m2000sp instrument, using an open-mode protocol. Two calibrators, spiked with a plasmid containing HIV-1 genome (10(3) and 10(5) cps/mL), were extracted and amplified to generate a master calibration curve. Precision, accuracy, linear dynamic range, limit of quantification (LOQ) and limit of detection (LOD) were determined. A cohort of patients, naive or chronically infected, was analysed.Results: Calibration curve was obtained from 42 replicates of standards (std(s)); precision was calculated (coefficients of variability [CVs] below 10%); accuracy was higher than 90%. Linearity covered the entire range tested (10-10(4) copies per reaction), and LOD (95%) was 12 copies per reaction. HIV-1 DNA was significantly higher (p < 0.0001) in drug-naive (62) than in chronically treated patients (50), and proviral loads correlated with lymphocytes (p = 0.0002) and CD4(+) (p < 0.0001) counts only in naive patients. Both groups displayed a significant inverse correlation between CD4(+) nadir and proviral loads. A significant correlation (p < 0.0001) between viraemia and HIV-1 reservoir was disclosed. No significant difference was obtained from the comparison between proviral loads on whole blood and peripheral blood mononuclear cells (PBMCs) from the same patient.Conclusions: The novelty of our approach relies on the selection of appropriate reference standard extracted and amplified as clinical specimens avoiding any underestimation of the reservoir. Results confirm HIV-1 DNA as a marker of disease progression, supporting the relationship between the width of latent reservoir and the immunological status of the patient.