Blinded, multicenter quality control study for the quantification of human immunodeficiency virus type 1 RNA in plasma by the Belgian AIDS reference laboratories

Analysis of the results of HIV-1, HCV and HBV viral loads of the SEIMC External Quality Control Program. Year 2018

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) and hepatitis B (HBV) and C virus (HCV) viral load determinations are among the most relevant markers for the follow-up of patients infected with these viruses. External quality control tools are crucial to ensure the accuracy of the results obtained by microbiology laboratories. This article summarised the results obtained from the 2018 SEIMC External Quality Control Programme for HIV-1, HCV, and HBV viral loads and HCV genotyping.

METHODS AND RESULTS

In the HIV-1 program, a total of five standards were sent. One standard consisted of seronegative human plasma, while the remaining four contained plasma from three different viremic patients, in the range of 2-5 log₁₀ copies/mL; two of these standards were identical, with the aim of determining repeatability. A significant proportion of the laboratories (28% on average) obtained values outside the accepted range (mean±0.25 log₁₀ copies/mL), depending on the standard and on the method used for quantification. Repeatability was good, with most laboratories reporting results within the limits (D<0.5 log₁₀ copies/mL). The HBV and HCV programme consisted of two standards with different viral load contents. Most of the participants, 87% in the case of HCV and 88% in the HBV, obtained all the results within the accepted range (mean±1.96 SD log₁₀ UI/mL).

CONCLUSIONS

Data from this analysis reinforce the utility of proficiency programmes to ensure the quality of the results obtained by a particular laboratory. Due to the marked interlaboratory variability, it is advisable to use the same method and the same laboratory for patient follow-up.

Analysis of the results of HIV-1, HCV and HBV viral loads of the SEIMC External Quality Control Programme. Year 2017

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) and hepatitis B (HBV) and C virus (HCV) viral load determinations are among the most relevant markers for the follow-up of patients infected with these viruses. External quality control tools are crucial to ensure the accuracy of the results obtained by microbiology laboratories. This article summarised the results obtained from the 2017 SEIMC External Quality Control Programme for HIV-1, HCV, and HBV viral loads and HCV genotyping.

METHODS AND RESULTS

In the HIV-1 programme, a total of five standards were sent. One standard consisted of seronegative human plasma, while the remaining four contained plasma from three different viremic patients, in the range of 2-5 log₁₀ copies/mL; two of these standards were identical, with the aim of determining repeatability. A significant proportion of the laboratories (35% on average) obtained values outside the accepted range (mean±0.25 log₁₀ copies/mL), depending on the standard and on the method used for quantification. Repeatability was good, with up to 94% of laboratories reporting results within the limits (D<0.5 log₁₀ copies/mL). The HBV and HCV programme consisted of two standards with different viral load contents. Most of the participants, 82% in the case of HCV and 87% in that of HBV, obtained all the results within the accepted range (mean±1.96 SD log₁₀ UI/mL).

CONCLUSIONS

Data from this analysis reinforce the utility of proficiency programmes to ensure the quality of the results obtained by a particular laboratory. Due to the marked interlaboratory variability observed, it is advisable to use the same method and laboratory for patient follow-up.

Analysis of the results of the SEIMC External Quality Control Programme for HIV-1, HCV, and HBV viral loads. Year 2016

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) and hepatitis B (HBV) and C virus (HCV) viral load determinations are among the most important markers for the follow-up of patients infected with these viruses. Microbiology laboratories have a variety of tools to ensure the accuracy of the results obtained, including external quality control programmes such as that of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC). This article summarises the results of the 2016 SEIMC External Quality Control Programme for HIV-1, HCV, and HBV viral loads.

METHODS AND RESULTS

In the HIV-1 programme, a total of 5 standards were sent. One standard consisted of seronegative human plasma, while the remaining 4 contained plasma from 3 different viremic patients, in the range of 2-5 log₁₀ copies/mL. A significant proportion of the laboratories (40% on average) obtained values out of the accepted range (mean ± 0.25 log₁₀ copies/mL), depending on the standard and on the method used for quantification. The HBV and HCV programme consisted of 2 standards with different viral load contents. Most of the participants, 86.5% in the case of HCV and 85.6% in the case of HBV, obtained results that were all within the accepted range (mean ± 1.96 SD log₁₀ UI/mL).

CONCLUSIONS

Data from this analysis reinforce the utility of proficiency programmes to ensure the quality of the results obtained by a particular laboratory. Due to the marked interlaboratory variability, it is advisable to use the same method and the same laboratory for patient follow-up. Supplement information: This article is part of a supplement entitled «SEIMC External Quality Control Programme. Year 2016», which is sponsored by Roche, Vircell Microbiologists, Abbott Molecular and Francisco Soria Melguizo, S.A. © 2019 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Interlaboratory Comparison of Six Real-Time PCR Assays for Detection of Bovine Leukemia Virus Proviral DNA

Quantitative real-time PCR (qPCR) is increasingly being used for the detection of bovine leukemia virus (BLV) proviral DNA. Nevertheless, quality control for the validation and standardization of such tests is currently lacking. Therefore, the present study was initiated by three Office International des Epizooties (OIE) reference laboratories and three collaborating laboratories to measure the interlaboratory variability of six already developed and available BLV qPCR assays. For that purpose, an international panel of 58 DNA samples reflecting the dynamic range of the majority of the assays was distributed to six testing centers. Based on qualitative results, the overall agreement among all six laboratories was moderate. However, significant variability in the measurement of the BLV proviral DNA copy number was observed among different laboratories. Quantitative PCR assays, even when performed by experienced staff, can yield large variability in BLV proviral DNA copy numbers without harmonization. Further standardization of different factors (i.e., utilization of unified protocols and unique calibrators) should increase interlaboratory agreement.

Assessment of the Cavidi ExaVir Load Assay for Monitoring Plasma Viral Load in HIV-2-Infected Patients

HIV plasma viral load is an established marker of disease progression and of response to antiretroviral therapy, but currently there is no commercial assay validated for the quantification of viral load in HIV-2-infected individuals. We sought to make the first clinical evaluation of Cavidi ExaVir Load (version 3) in HIV-2-infected patients. Samples were collected from a total of 102 individuals living in Cape Verde, and the HIV-2 viral load was quantified by both ExaVir Load and a reference in-house real-time quantitative PCR (qPCR) used in Portugal in 91 samples. The associations between viral load and clinical prognostic variables (CD4⁺ T cell counts and antiretroviral therapy status) were similar for measurements obtained using ExaVir Load and qPCR. There was no difference between the two methods in the capacity to discriminate between nonquantifiable and quantifiable HIV-2 in the plasma. In samples with an HIV-2 viral load quantifiable by both methods (n = 27), the measurements were highly correlated (Pearson r = 0.908), but the ExaVir Load values were systematically higher relative to those determined by qPCR (median difference, 0.942 log₁₀ copies/ml). A regression model was derived that enables the conversion of ExaVir Load results to those that would have been obtained by the reference qPCR. In conclusion, ExaVir Load version 3 is a reliable commercial assay to measure viral load in HIV-2-infected patients and therefore a valuable alternative to the in-house assays in current use.

Systematic review of the performance of HIV viral load technologies on plasma samples

Background

Viral load (VL) monitoring is the standard of care in developing country settings for detecting HIV treatment failure. Since 2010 the World Health Organization has recommended a phase-in approach to VL monitoring in resource-limited settings. We conducted a systematic review of the accuracy and precision of HIV VL technologies for treatment monitoring.

Methods and Findings

A search of Medline and Embase was conducted for studies evaluating the accuracy or reproducibility of commercially available HIV VL assays. 37 studies were included for review including evaluations of the Amplicor Monitor HIV-1 v1.5 (n = 25), Cobas TaqMan v2.0 (n = 11), Abbott RealTime HIV-1 (n = 23), Versant HIV-1 RNA bDNA 3.0 (n = 15), Versant HIV-1 RNA kPCR 1.0 (n = 2), ExaVir Load v3 (n = 2), and NucliSens EasyQ v2.0 (n = 1). All currently available HIV VL assays are of sufficient sensitivity to detect plasma virus levels at a lower detection limit of 1,000 copies/mL. Bias data comparing the Abbott RealTime HIV-1, TaqMan v2.0 to the Amplicor Monitor v1.5 showed a tendency of the Abbott RealTime HIV-1 to under-estimate results while the TaqMan v2.0 overestimated VL counts. Compared to the Amplicor Monitor v1.5, 2–26% and 9–70% of results from the Versant bDNA 3.0 and Abbott RealTime HIV-1 differed by greater than 0.5log₁₀. The average intra and inter-assay variation of the Abbott RealTime HIV-1 were 2.95% (range 2.0–5.1%) and 5.44% (range 1.17–30.00%) across the range of VL counts (2log₁₀–7log₁₀).

Conclusions

This review found that all currently available HIV VL assays are of sufficient sensitivity to detect plasma VL of 1,000 copies/mL as a threshold to initiate investigations of treatment adherence or possible treatment failure. Sources of variability between VL assays include differences in technology platform, plasma input volume, and ability to detect HIV-1 subtypes. Monitoring of individual patients should be performed on the same technology platform to ensure appropriate interpretation of changes in VL.

Prospero registration # CD42013003603.

[Analysis of the results of the 2010 External Quality Control Program of the Spanish Society of Infectious Diseases and Clinical Microbiology for HIV-1, HCV, and HBV viral loads]

Human immunodeficiency virus type 1 (HIV-1) and hepatitis B (HBV) and C virus (HCV) viral load determinations are among the most important markers for the follow-up of patients infected with these viruses. External quality control tools are crucial to ensure the accuracy of the results obtained by microbiology laboratories. This article summarized the results obtained in the 2010 External Quality Control Program of the Spanish Society of Infectious Diseases and Clinical Microbiology for HIV-1, HCV, and HBV viral loads and HCV genotyping. In the HIV-1 program, a total of five standards were sent. One standard consisted of seronegative human plasma, while the remaining four contained plasma from three different viremic patients, in the range of 3-5 log(10) copies/mL; two of these standards were identical, with the aim of determining repeatability. A significant proportion of the laboratories (22.6% on average) obtained values out of the accepted range (mean ± 0.2 log(10)copies/mL), depending on the standard and on the method used for quantification. Repeatability was very good, with up to 95% of laboratories reporting results within the limits (Δ<0.5 log(10)copies/mL). The HBV and HCV program consisted of two standards with different viral load contents. Most of the participants, 86.1% in the case of HCV and 87.1% in HBV, obtained all the results within the accepted range (mean ± 1.96 SD log(10)UI/mL). Post-analytical errors due to mistranscription of the results were detected in these controls. Data from this analysis reinforce the utility of proficiency programs to ensure the quality of the results obtained by a particular laboratory, as well as the importance of the post-analytical phase in overall quality. Due to interlaboratory variability, use of the same method and the same laboratory for patient follow-up is advisable.

An international collaboration to standardize HIV-2 viral load assays: results from the 2009 ACHI(E)V(2E) quality control study

Accurate HIV-2 plasma viral load quantification is crucial for adequate HIV-2 patient management and for the proper conduct of clinical trials and international cohort collaborations. This study compared the homogeneity of HIV-2 RNA quantification when using HIV-2 assays from ACHI(E)V(2E) study sites and either in-house PCR calibration standards or common viral load standards supplied to all collaborators. Each of the 12 participating laboratories quantified blinded HIV-2 samples, using its own HIV-2 viral load assay and standard as well as centrally validated and distributed common HIV-2 group A and B standards (http://www.hiv.lanl.gov/content/sequence/HelpDocs/subtypes-more.html). Aliquots of HIV-2 group A and B strains, each at 2 theoretical concentrations (2.7 and 3.7 log(10) copies/ml), were tested. Intralaboratory, interlaboratory, and overall variances of quantification results obtained with both standards were compared using F tests. For HIV-2 group A quantifications, overall and interlaboratory and/or intralaboratory variances were significantly lower when using the common standard than when using in-house standards at the concentration levels of 2.7 log(10) copies/ml and 3.7 log(10) copies/ml, respectively. For HIV-2 group B, a high heterogeneity was observed and the variances did not differ according to the type of standard used. In this international collaboration, the use of a common standard improved the homogeneity of HIV-2 group A RNA quantification only. The diversity of HIV-2 group B, particularly in PCR primer-binding regions, may explain the heterogeneity in quantification of this strain. Development of a validated HIV-2 viral load assay that accurately quantifies distinct circulating strains is needed.

[Analysis of the results of the HIV-1 and HCV viral load of the SEIMC External Quality Control Program. Year 2009]

Human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) viral load determinations are among the most important markers in the follow-up of patients infected with these viruses. External quality control tools are crucial to ensure the accuracy of the results obtained by microbiology laboratories. This article summarizes the results obtained from the SEIMC's External Quality Control Program for HIV-1 and HCV viral loads in 2009. In the HIV-1 program, a total of five standards were sent. One standard consisted of seronegative human plasma, while the remaining four contained plasma from three different viremic patients, in the range of 2-5 log(10) copies/mL; two of these standards were identical, aiming to determine repeatability. A significant proportion of the laboratories (21.5% on average) obtained values outside the accepted range (mean ± 0.2 log(10) copies/mL), depending on the standard and on the method used for quantification. Repeatability was very good, with up to 95 % of laboratories reporting results within the accepted limits (Δ<0.5 log10 copies/mL). Post-analytical errors due to mistranscription of the results were detected for HIV-1. The HCV program consisted of two standards with different viral load contents. Most of the participants (79.7%) obtained results within the accepted range (mean ± 1.96 SD log(10) UI/mL). Data from this analysis reinforce the utility of proficiency programs to ensure the quality of the results obtained by a particular laboratory, as well as the importance of the post-analytical phase in overall quality. Due to marked interlaboratory variability, use of the same method and the same laboratory for patient follow-up is advisable.

International multicenter study to assess a panel of reference materials for quantification of simian immunodeficiency virus RNA in plasma

An international multicenter study was conducted to assess the performance of a panel of simian immunodeficiency virus (SIV) RNA reference materials for plasma viral load determinations. Reliable quantification was demonstrated across an approximately 6 log(10) dynamic range. Availability of external reference materials will enable independent calibration of SIV plasma viral load assays.

Clinical prognostic value of RNA viral load and CD4 cell counts during untreated HIV-1 infection--a quantitative review

Background

The prognostic value of CD4 counts and RNA viral load for identifying treatment need in HIV-infected individuals depends on (a) variation within and among individuals, and (b) relative risks of clinical progression per unit CD4 or RNA difference.

Methodology/Principal Findings

We reviewed these measurements across (a) 30 studies, and (b) 16 cohorts of untreated seropositive adults. Median within-population interquartile ranges were 74,000 copies/mL for RNA with no significant change during the course of infection; and 330 cells/µL for CD4, with a slight proportional increase over infection. Applying measurement and physiological fluctuations observed on chronically infected patients, we estimate that 45% of population-level variation in RNA, and 25% of variation in CD4, were due to within-patient fluctuations. Comparing a patient with RNA at upper 75^th centile with a patient at median RNA, 5-year relative risks were 1.4 (95% CI 1.2–1.7) for AIDS and 1.5 (1.3–1.9) for death, without change over the course of infection. In contrast, for a patient with CD4 count at the lower 75^th centile, relative risks increased from 1.0 at seroconversion to maxima of 6.3 (4.4–8.9) for AIDS and 5.5 (2.7–10.1) for death by year 6, when the population median had fallen to 300 cells/µL. Below 300 cells/µL, prognostic power did not increase, due to a narrower CD4 range.

Conclusions

Findings support the current WHO recommendation (used with clinical criteria) to start antiretroviral treatment in low-income settings at CD4 thresholds of 200–350 cells/µL, without pre-treatment RNA monitoring – while not precluding earlier treatment based on clinical, socio-demographic or public health criteria.

Quality control assessment of human immunodeficiency virus type 2 (HIV-2) viral load quantification assays: results from an international collaboration on HIV-2 infection in 2006

Human immunodeficiency virus type 2 (HIV-2) RNA quantification assays used in nine laboratories of the ACHI(E)V(2E) (A Collaboration on HIV-2 Infection) study group were evaluated. In a blinded experimental design, laboratories quantified three series of aliquots of an HIV-2 subtype A strain, each at a different theoretical viral load. Quantification varied between laboratories, and international standardization of quantification assays is strongly needed.

A simple competitive RT-PCR assay for quantitation of HIV-1 subtype B and non-B RNA in plasma

An easy, inexpensive competitive RT-PCR assay for HIV-1 RNA quantitation was constructed. A 138-bp sequence in the HIV-1 gag p24 region was selected as the target and co-amplified with competitor RNA containing an internal 44-bp deletion. Quantitation of serial dilutions of control RNA samples prepared from the LAI isolate demonstrated a good linearity (R(2)=0.991) within the range between 10 and 250 copies/sample. The detection limit of the assay was determined to be 3.8 copies/sample by Probit analysis and corresponded to 110 copies/ml in plasma. The intra-assay CV value was 9.1%, and the inter-assay value was 25.9%. Both were comparable to those obtained with commercially available HIV-1 RNA quantitation kits. The correlation efficient for the results obtained in 47 plasma samples from HIV-1-infected individuals (subtype A in 1, subtype B in 25, subtype C in 4, subtype F in 1, and CRF01 AE in 16) with the competitive RT-PCR and Cobas Amplicor HIV-1 Monitor test v1.5 was 0.956 for subtype B and 0.947 for subtype non-B. The assay devised is a good alternative for monitoring antiretroviral therapy in resource-poor countries.

Ultrasensitive monitoring of HIV-1 viral load by a low-cost real-time reverse transcription-PCR assay with internal control for the 5' long terminal repeat domain

BACKGROUND

Current HIV-1 viral-load assays are too expensive for resource-limited settings. In some countries, monitoring of antiretroviral therapy is now more expensive than treatment itself. In addition, some commercial assays have shown shortcomings in quantifying rare genotypes.

METHODS

We evaluated real-time reverse transcription-PCR with internal control targeting the conserved long terminal repeat (LTR) domain of HIV-1 on reference panels and patient samples from Brazil (n = 1186), South Africa (n = 130), India (n = 44), and Germany (n = 127).

RESULTS

The detection limit was 31.9 IU of HIV-1 RNA/mL of plasma (> 95% probability of detection, Probit analysis). The internal control showed inhibition in 3.7% of samples (95% confidence interval, 2.32%-5.9%; n = 454; 40 different runs). Comparative qualitative testing yielded the following: Roche Amplicor vs LTR assay (n = 431 samples), 51.7% vs 65% positives; Amplicor Ultrasensitive vs LTR (n = 133), 81.2% vs 82.7%; BioMerieux NucliSens HIV-1 QT (n = 453), 60.5% vs 65.1%; Bayer Versant 3.0 (n = 433), 57.7% vs 55.4%; total (n = 1450), 59.0% vs 63.8% positives. Intra-/interassay variability at medium and near-negative concentrations was 18%-51%. The quantification range was 50-10,000,000 IU/mL. Viral loads for subtypes A-D, F-J, AE, and AG yielded mean differences of 0.31 log(10) compared with Amplicor in the 10(3)-10(4) IU/mL range. HIV-1 N and O were not detected by Amplicor, but yielded up to 180 180.00 IU/mL in the LTR assay. Viral loads in stored samples from all countries, compared with Amplicor, NucliSens, or Versant, yielded regression line slopes (SD) of 0.9 (0.13) (P < 0.001 for all).

CONCLUSIONS

This method offers all features of commercial assays and covers all relevant genotypes. It could allow general monitoring of antiretroviral therapy in resource-limited settings.

Results of the first World Health Organization international collaborative study of detection of human papillomavirus DNA

Twenty-nine laboratories in 12 countries participated in a study to assess the performance of various human papillomavirus (HPV) detection assays through the use of a recombinant HPV DNA standard reagent panel. The panel was designed by a group of HPV experts, and samples were prepared and distributed by the World Health Organization International Laboratory for Standards and Biologicals in The Netherlands. Each panel consisted of 24 coded samples including a dilution series for HPV types 16 and 18, alone or in combination with five other high-risk (HR) HPV types including HPV types 31, 33, 35, 45, and 52, the low-risk HPV type 6, and a negative control. Qualitative assays were generally consistent across laboratories, and most invalid results reflected a lack of HPV test sensitivity. The combined data sets had a proficiency for HPV 16 of 62.5% (15/24) and for HPV 18 of 73.9% (17/23). HPV 31 was the least accurately detected by participating laboratories. Approximately half of participating laboratories failed to detect high concentrations of HPV 31 and, to a lesser extent, to detect HPV types 35, 52, and 6. The panel sample materials offer a source of renewable and reproducible material that could be used in the future development of international standard reagents for calibration of HPV DNA assays and kits.