Abbott RealTime HIV-1 Research Articles

Measures of viral load using Abbott RealTime HIV-1 Assay on venous and fingerstick dried blood spots from provider-collected specimens in Malawian District Hospitals

BackgroundViral suppression is a key indicator of antiretroviral therapy (ART) response among HIV-infected patients. Dried blood spots (DBS) are an appealing alternative to conventional plasma-based virologic testing, improving access to monitoring in resource-limited settings. However, validity of DBS obtained from fingerstick in field settings remains unknown. ObjectivesInvestigate feasibility and accuracy of DBS vs plasma collected by healthcare workers in real-world settings of remote hospitals in Malawi. Compare venous DBS to fingerstick DBS for identifying treatment failure. Study designWe recruited patients from ART clinics at two district hospitals in Malawi, collecting plasma, venous DBS (vDBS), and fingerstick DBS (fsDBS) cards for the first 149 patients, and vDBS and fsDBS only for the subsequent 398 patients. Specimens were tested using Abbott RealTime HIV-1 Assay (lower detection limit 40 copies/ml (plasma) and 550 copies/ml (DBS)). Results21/149 (14.1%) had detectable viremia (>1.6 log copies/ml), 13 of which were detectable for plasma, vDBS, and fsDBS. Linear regression demonstrated high correlation for plasma vs. DBS (vDBS: β=1.19, R2=0.93 (p<0.0001); fsDBS β=1.20, R2=0.90 (p<0.0001)) and vDBS vs. fsDBS (β=0.88, R2=0.73, (p<0.0001)). Mean difference between plasma and vDBS was 1.1 log copies/ml [SD: 0.27] and plasma and fsDBS 1.1 log copies/ml [SD: 0.31]. At 5000 copies/ml, sensitivity was 100%, and specificity was 98.6% and 97.8% for vDBS and fsDBS, respectively, compared to plasma. ConclusionsDBS from venipuncture and fingerstick perform well at the failure threshold of 5000 copies/ml. Fingerstick specimen source may improve access to virologic treatment monitoring in resource-limited settings given task-shifting in high-volume, low-resource facilities.

Clinical implications of elevated HIV-1 viral load results obtained from samples stored frozen in vacutainer plasma preparation tubes

Studies have demonstrated that plasma samples collected and stored frozen using vacutainer plasma preparation tubes (PPT) may result in falsely elevated viral load (VL) values with the Roche COBAS TaqMan HIV-1 v1.0 test. At the University of Connecticut Health Center, a total of 349 samples from HIV-1-infected patients on HAART were collected and stored frozen in PPT. Viral load (VL) results were obtained using the Roche COBAS TaqMan HIV-1 v2.0 test (CTM v2.0) and Abbott RealTime HIV-1 assay (RealTime HIV-1). Of the 349 samples, 260 (74.5%) had VL values that differed by >0.5log10copies/mL; 64 of these were quantified by both assays. The remaining 196 samples were detected by CTM v2.0 but not detected in RealTime HIV-1: 62 of the most discordant samples in this category (CTM v2.0 detected/RealTime HIV-1 not detected) were further analyzed using two nested RT-PCR assays targeting pol integrase: full-length (864nt) and a highly conserved subregion (134nt). No HIV-1 RNA was detected in the discordant samples, confirming RealTime HIV-1 results. The increase in VL reactivity with the CTM v2.0 assay was presumably due to proviral DNA captured by the CTM total nucleic acid extraction chemistry but not the RNA-specific extraction procedure used in RealTime HIV-1. These results suggest that using CTM v2.0 with samples frozen in PPT could have significant clinical implications for HIV-1 patient management.

Field evaluation of Abbott Real Time HIV-1 Qualitative test for early infant diagnosis using dried blood spots samples in comparison to Roche COBAS Ampliprep/COBAS TaqMan HIV-1 Qual Test in Kenya

Timely diagnosis and treatment of infants infected with HIV are critical for reducing infant mortality. High-throughput automated diagnostic tests like Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 Qual Test (Roche CAPCTM Qual) and the Abbott Real Time HIV-1 Qualitative (Abbott Qualitative) can be used to rapidly expand early infant diagnosis testing services. In this study, the performance characteristics of the Abbott Qualitative were evaluated using two hundred dried blood spots (DBS) samples (100 HIV-1 positive and 100 HIV-1 negative) collected from infants attending the antenatal facilities in Kisumu, Kenya. The Abbott Qualitative results were compared to the diagnostic testing completed using the Roche CAPCTM Qual in Kenya. The sensitivity and specificity of the Abbott Qualitative were 99.0% (95% CI: 95.0–100.0) and 100.0% (95% CI: 96.0–100.0), respectively, and the overall reproducibility was 98.0% (95% CI: 86.0–100.0). The limits of detection for the Abbott Qualitative and Roche CAPCTM Qual were 56.5 and 6.9copies/mL at 95% CIs (p=0.005), respectively. The study findings demonstrate that the Abbott Qualitative test is a practical option for timely diagnosis of HIV in infants.

Discordances with HIV-1 RNA quantitative determinations by three commercial assays in Pointe Noire, Republic of Congo

Accurate HIV-1 RNA quantitation is required to support the scale up of antiretroviral therapy in African countries. Extreme HIV-1 genetic variability in Africa may affect the ability of commercially available assays to detect and quantify HIV-1 RNA accurately. The aim of this study was to compare three real-time PCR assays for quantitation of plasma HIV-1 RNA levels in patients from the Republic of Congo, an area with highly diversified HIV-1 subtypes and recombinants.The Abbott RealTime HIV-1, BioMérieux HIV-1 EasyQ test 1.2 and Cobas AmpliPrep/Cobas TaqMan HIV-1 1.0 were compared for quantitation of HIV-1 RNA in 37 HIV-1 seropositive pregnant women enrolled in the Kento-Mwana project for prevention of mother-to-child transmission in Pointe-Noire, Republic of Congo. The sample panel included a variety of HIV-1 subtypes with as many as 21 (56.8%) putative unique recombinant forms.Qualitative detection of HIV-1 RNA was concordant by all three assays in 33/37 (89.2%) samples. Of the remaining 4 (10.8%) samples, all were positive by Roche, three by Abbott and none by BioMérieux. Differences exceeding 1Log in positive samples were found in 4/31 (12.9%), 10/31 (32.3%) and 5/31 (16.1%) cases between Abbott and BioMérieux, Roche and BioMérieux, and Abbott and Roche, respectively.In this sample panel representative of highly polymorphic HIV-1 in Congo, the agreement among the three assays was moderate in terms of HIV-1 RNA detectability and rather inconsistent in terms of quantitation.

Systematic Review of the Performance of HIV Viral Load Technologies on Plasma Samples

BackgroundViral 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 FindingsA 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).ConclusionsThis 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.

Performance of the Abbott RealTime HIV-1 assay versus the Roche Amplicor HIV-1 MonitorTM Test, v1.5, UltraSensitive assay for samples with low plasma HIV-1 RNA copy numbers

Performance of the Abbott RealTime HIV-1 assay versus the Roche Amplicor HIV-1 MonitorTM Test, v1.5, UltraSensitive assay for samples with low plasma HIV-1 RNA copy numbers

Immuno-haematologic and virologic responses and predictors of virologic failure in HIV-1 infected adults on first-line antiretroviral therapy in Cameroon

BackgroundContemporary data on the immunologic, haematologic and virologic responses and predictors of virologic failure after initiation of free antiretroviral treatment in Cameroon are needed to evaluate the current treatment-monitoring algorithm and to complement efforts to scale-up and improve on the management of HIV infections.MethodsThis was a cross-sectional study conducted between October 2010 and June 2012. A total of 951 participants aged 18–74 years were recruited from selected approved HIV treatment centres of the Northwest and Southwest regions. This comprised 247 males and 704 females. Demographic, self-reported risk behaviours and socioeconomic data were obtained using a structured questionnaire. Full blood and CD4 + T-cell counts were done using standard automated techniques. Determination of viral load (VL) was done using Abbott RealTime HIV-1 m2000™ system. Data was analysed using SPSS version 17. The statistical significance level was P < 0.05.ResultsThe median duration of antiretroviral therapy (ART) was 24 months. The population mean CD4 + T-cell count was 255.3 cells/μL [95% CI, 236.8 – 273.9]. Overall, 45.9%, 43.8% and 10.2% of the participants had CD4 + T-cell counts of < 200 cells/μL, 200–499 cells/μL and > 500 cells/μL respectively. Anaemia was present in 26.2% of the participants with 62.3%, 25.7% and 12% described as mild, moderate and severe anaemia respectively. Virologic failure occurred in 23.2% of the participants with 12.3% having VL > 10,000 RNA copies/mL. Meanwhile 76.8% of patients attained adequate viral suppression with 40.8% having undetectable viral load. The age group 18–29 years (p = 0.024), co-infection with tuberculosis (p = 0.014), anaemia (p = 0.028) and distance from the treatment centre (p = 0.011) independently predicted virologic failure.ConclusionThe majority of the participants achieved adequate viral suppression after ≥ 6 months of ART. Despite these favourable immuno-haematologic and virologic outcomes, the National AIDS Control Program should step-up efforts to improve on antiretroviral drug distribution, as well as proper assessment and management of anaemia, foster early diagnosis and treatment of tuberculosis and enhance treatment adherence counselling especially in younger patients.

Measures of viral load using Abbott RealTime HIV-1 Assay on venous and fingerstick dried blood spots from provider-collected specimens in Malawian District Hospitals

Measures of viral load using Abbott RealTime HIV-1 Assay on venous and fingerstick dried blood spots from provider-collected specimens in Malawian District Hospitals

Significant impact of non‐B HIV‐1 variants genetic diversity in Gabon on plasma HIV‐1 RNA quantitation

Evaluations of HIV-1 RNA viral load assays are lacking in Central Africa. The main objective of our study was to assess the reliability of HIV-1 RNA results obtained with three different assays for samples collected in Gabon. A total of 137 plasma specimens were assessed for HIV-1 RNA using the Abbott RealTime HIV-1® and Nuclisens HIV-1 EasyQ® version 2.0 assays. It included HIV-1 non-B samples (n = 113) representing six subtypes, 10 CRFs and 18 URFs from patients infected with HIV-1 and treated with antiretrovirals that were found HIV-1 RNA positive (≥300 copies/ml) with the Generic HIV viral load® assay; and samples (n = 24) from untreated individuals infected with HIV-1 but showing undetectable (<300 copies/ml) results with the Biocentric kit. For samples found positive with the Generic HIV viral load® test, correlation coefficients obtained between the three techniques were relatively low (R = 0.65 between Generic HIV viral load® and Abbott RealTime HIV-1®, 0.50 between Generic HIV viral load® and Nuclisens HIV-1 EasyQ®, and 0.66 between Abbott RealTime HIV-1® and Nuclisens HIV-1 EasyQ®). Discrepancies by at least one log10 were obtained for 19.6%, 33.7%, and 20% of samples, respectively, irrespective of genotype. Most of samples (22/24) from untreated study patients, found negative with the Biocentric kit, were also found negative with the two other techniques. In Central Africa, HIV-1 genetic diversity remains challenging for viral load testing. Further studies are required in the same area to confirm the presence of HIV-1 strains that are not amplified with at least two different viral load assays.

Cobas Ampliprep/Cobas TaqMan HIV-1 v2.0 Assay: Consequences at the Cohort Level

BackgroundHigh-sensitive real-time PCR assays are routinely used to monitor HIV-1 infected subjects. Inter-assay discrepancies have been described at the low viral load (VL) end, where clinical decisions regarding possible virological rebound are based.MethodsA retrospective study was performed to analyze frequencies of viral blips after transition to the COBAS Ampliprep/COBAS TaqMan v2.0 HIV-1 assay (Taqman v2.0) in patients with prior undetectable VLs as measured with the Roche Cobas Ampliprep Amplicor HIV-1 Monitor Test, v1.5 (Amplicor) and was evaluated in comparison to a group of patients monitored with the Abbott Real-time HIV-1 assay (Abbott RT) during the same period of time.Results85 of 373 patients with VLs below the limit of quantification with Amplicor had VLs >50 copies/mL after transition to the TaqMan v2.0 assay. Among these 74.1% had VLs ranging from 50–499 copies/mL, 22.9% had VLs >500 copies/mL. From 22 patients with initial Taqman v2.0 based VLs exceeding 500 copies/mL, 6 patients had VLs <20 copies/mL after novel VL measurement on a next visit. In our control group with VL quantification using the Abbott RT assay, only 1 patient became detectable and showed a VL of <40 copies/mL after new measurement.ConclusionsTransition to the Taqman v2.0 assay was accompanied by an increase of quantifiable HIV-1 VLs in patients with long term viral suppression under antiretroviral therapy that might be attributed to technical shortcomings of the Taqman v2.0 assay. A high test variability at the low VL end but also beyond was observed, making meaningful clinical interpretation of viral blips derived from different assays difficult.

Minimal sequence variability of the region of HIV-1 integrase targeted by the Abbott RealTime HIV-1 viral load assay in clinical specimens with reduced susceptibility to raltegravir

The Abbott RealTime (ART) HIV-1 assay targets the integrase region and is designed to tolerate mismatches. Variability in integrase sequences comprising the assay target regions from >1000 clinical specimens submitted for phenotypic and genotypic raltegravir resistance testing were analyzed. In this large collection of sequences from clinical specimens, the number and location of raltegravir resistance associated mutations did not differ from those tested previously and shown not to result in under-estimation of viral loads.

Co-infection: new battlegrounds in HIV/AIDS

Co-infection: new battlegrounds in HIV/AIDS

Measuring the Unknown

Measuring the Unknown

Comparison of the NucliSENS EasyQ HIV-1 v2.0 with Abbott m2000rt RealTime HIV-1 assay for plasma RNA quantitation in different HIV-1 subtypes

Quantitation of HIV-1 RNA levels in plasma has significant prognostic value since high viral load concentrations in plasma are associated with a faster disease progression. Viral load testing became one the most important tools for monitoring HIV patients. New real time methodologies to quantify HIV viral load had arisen in the last decade. HIV is a virus with a high genetic variability, with the potential to negatively affect the performance of the viral load assays. Consequently, any new assay should be challenged against, at least, the most prevalent HIV-1 genetic variants. In the present study, the new version of NucliSENS EasyQ® HIV-1 (Version 2.0) quantitative assay was compared with another ultra-sensitive test – Abbott RealTime HIV-1 – using 175 plasma samples from patients infected with several HIV-1 subtypes and recombinant forms: subtype B (41, 23%), subtype C (19, 11%), subtype G (76, 44%), and CRF02_AG (39, 22%). Overall, there was agreement between the assays in 95.43% of the samples. Both assays have a very good dynamic range [1.4–6.9] and [1.60–7.0] log10 copies/mL and excellent correlation in samples with various subtypes. Based on the fact that no clinically significant differences were observed in the viral load measurements by these two assays, HIV-1 subtypes are quantified equally by both assays. However due to HIV diversity, mainly in regions were non B subtypes are predominant more evaluations are needed, so we do not recommend to switch platform during longitudinal viral load monitoring.

Monitoring of HIV viral load, CD4 cell count, and clinical assessment versus clinical monitoring alone for antiretroviral therapy in low-resource settings (Stratall ANRS 12110/ESTHER): a cost-effectiveness analysis

In low-income countries, the use of laboratory monitoring of patients taking antiretroviral therapy (ART) remains controversial in view of persistent resource constraints. The Stratall trial did not show that clinical monitoring alone was non-inferior to laboratory and clinical monitoring in terms of immunological recovery. We aimed to evaluate the costs and cost-effectiveness of the ART monitoring approaches assessed in the Stratall trial. The randomised, controlled, non-inferiority Stratall trial was done in a decentralised setting in Cameroon. Between May 23, 2006, and Jan 31, 2008, ART-naive adults were randomly assigned (1:1) to clinical monitoring (CLIN) or viral load and CD4 cell count plus clinical monitoring (LAB) and followed up for 24 months. We calculated costs, number of life-years saved (LYS), and incremental cost-effectiveness ratios (ICERs) with data from patients who had been followed up for at least 6 months. We considered two cost scenarios in which viral load plus CD4 cell count tests cost either US$95 (scenario 1; Abbott RealTime HIV-1 assay) or $63 (scenario 2; generic assay). We compared ICERs with a WHO-recommended threshold of three times the per-person gross domestic product (GDP) for Cameroon ($3670-3800) and an alternative lower threshold of $2385 to determine cost-effectiveness. We assessed uncertainty with one-way sensitivity analyses and cost-effectiveness acceptability curves. 188 participants who underwent LAB and 197 who underwent CLIN were followed up for at least 6 months. In scenario 1, LAB increased costs by a mean of $489 (SD 430) per patient and saved 0·103 life-years compared with CLIN (ICER of $4768 [95% CI 3926-5613] per LYS). In scenario 2, the incremental mean cost of LAB was $343 (SD 425) -ie, an ICER of $3339 (2507-4173) per LYS. A combined strategy in which LAB would only be used in patients starting ART with a CD4 count of 200 cells per μL or fewer suggests that 0·120 life-years would be saved at an additional cost of $259 per patient in scenario 1 (ICER of $2167 [95% CI 1314-3020] per LYS) and $181 in scenario 2 (ICER of $1510 [692-2329] per LYS) when compared with CLIN. Laboratory monitoring was not cost effective in 2006-10 compared with clinical monitoring when the Abbott RealTime HIV-1 assay was used according to the $3670 cost-effectiveness threshold (three times per-person GDP in Cameroon), but it might be cost effective if a generic in-house assay is used. French National Agency for Research on AIDS and Viral Hepatitis (ANRS) and Ensemble pour une Solidarité Thérapeutique Hospitalière En Réseau (ESTHER).

HIV Type-1 Group O Infection in Gabon: Low Prevalence Rate But Circulation of Genetically Diverse and Drug-Resistant HIV Type-1 Group O Strains

The goals of this study conducted in Gabon were to determine the prevalence rate of HIV-1 group O (HIV-1/O) infections and to characterize the genetic diversity of HIV-1/O strains as well as implications on antiretroviral (ARV) drug resistance. During 2010-2011, 1,176 samples from HIV-positive subjects were tested at the CIRMF (Centre International de Recherches Médicales de Franceville) retrovirology laboratory using an in-house serotyping assay. Plasma HIV-1/O RNA viral loads (VL) were determined using the Abbott RealTime HIV-1 assay. After full genome sequencing, drug resistance patterns were analyzed using two different algorithms (Agence Nationale de Recherches sur le SIDA et les hépatites virales and Stanford). Overall, four subjects (0.34%) were diagnosed as HIV-1/O infected. One subject, untreated by ARVs, died 2 months after HIV-1/O diagnosis. One was lost to follow-up. Two additional patients, treated with nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens, showed CD4 counts <200/mm(3) and VL results of 101,000 and 10,050 cp/ml. After full-length genome sequencing of these two strains, we found a wide range of natural polymorphism in the protease (≥15 substitutions) and gp41 (N42D mutation) genes, as well as in the gag and gag-pol cleavage sites. No resistance mutation was detected in the integrase gene. These two strains harbored the Y181C mutation making them resistant to NNRTIs. M41L, M184V, and T215Y mutations were also found for one strain, making it resistant to all NRTIs by the Stanford algorithm. Even if HIV-1/O infection is low in Gabon, an accurate diagnosis and a reliable virological follow-up are required in Central Africa to optimize ARV treatments of HIV-1/O-infected patients.

Comparative evaluation of the Artus HIV-1 QS-RGQ assay and the Abbott RealTime HIV-1 assay for the quantification of HIV-1 RNA in plasma

BackgroundThe quantitative measurement of HIV-1 RNA levels in plasma (‘viral load’) is essential in the management of HIV-infected patients. ObjectiveThe new Artus HIV-1 QS-RGQ assay (‘ArtusHIV’) for HIV-1 RNA quantification in plasma was compared to the Abbott RealTime HIV-1 assay (‘RealTime’) following automated RNA isolation by the QIAsymphony and Abbott m2000 extractors, respectively. Emphasis was placed on assay performance with diverse HIV-1 subtypes and in patients receiving antiretroviral therapy (ART). Study designPlasma from 211 patients (105 subtype B, 87 non-B subtypes; 147 on ART) and serial dilutions of the WHO 2nd International HIV-1 RNA Standard (WHO-IS) were tested by the two assays in parallel. Assay relationship and agreement were determined by linear regression, correlation analysis, and Bland–Altman analysis. ResultsWith 125 specimens quantified by both assays, measurements were linearly associated and strongly correlated. Overall Artus reported higher levels by mean 0.24 (95% confidence interval [CI] 0.16–0.32) log10 copies/ml (P<0.0001); 5 samples (subtypes A, B, CRF01, CRF03) fell outside the 95% agreement. Discordant results were obtained with 11 and 13 samples quantified by either ArtusHIV or RealTime alone respectively, at levels generally close to the lower limit of quantification, giving an overall discordance rate of 24/211 (11%). Both assays generally under-quantified the WHO-IS by between 0.1 and 0.4 log10 copies/ml across seven dilutions. ConclusionsThe ArtusHIV assay offers performance comparable to that of the RealTime assay across a wide range of HIV-1 subtypes and among both treated and untreated patients.

Analytical sensitivity of three real-time PCR assays for measuring subtype B HIV-1 RNA

BackgroundLack of HIV RNA during antiretroviral therapy (ART) is regarded as a desirable outcome. Commercial assays of HIV virus load now need to detect virus RNA concentrations below 50c/ml and several of them have claimed a limit of detection (LOD) of 20–45c/ml. Objectives and study designWe have compared the performances of three commercial assays of HIV RNA, the Abbott RealTime HIV-1, the Qiagen Artus RG HIV-1 and the Roche Cobas Ampliprep Cobas TaqMan (CAPCTM) HIV-1 vs 2.0 using replicate of specimens with HIV-1 subtype B RNA concentrations of 20–200c/ml. ResultsDespite fair-to-moderate agreement between the three assays, probit analysis showed that their LODs differed; they were 81, 65 and 18c/ml respectively. The CAPCTM HIV-1 vs 2.0 values were higher than those of the other two; the maximum difference was 0.26logc/ml. By testing 20 replicate of each concentration, coefficients of variation were between 0.6% and 9.2% (Abbott RealTime HIV-1), 10.3% and 38% (Qiagen Artus RG HIV-1) and 5.2% and 13.1% (Roche CAPCTM HIV-1 vs 2.0). The three assays also differed in their reproducibility and linearity for virus loads of 50–200c/ml. ConclusionThe analytical performances of commercial virus load assays differ. Direct comparisons of widely used commercial assays in clinical studies could help to identify the residual viremia that is clinically relevant for effective long term therapy.

Comparison of Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 test version 2.0 (CAP/CTM v2.0) with other real-time PCR assays in HIV-1 monitoring and follow-up of low-level viral loads

Viral load monitoring of HIV-1 has become standard of care in HIV-1 positive patients. In this study, we evaluated the performance characteristics of the Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 test version 2.0 (CAP/CTM v2.0) in comparison with Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 test version 1.0 (CAP/CTM v1.0) and Abbott RealTime HIV-1 assay (m2000), with special emphasis on the quantitation of clinically controversial low-level viral loads. The performance characteristics of CAP/CTM v2.0 were confirmed by the validation study. All three assays performed comparably, with Abbott m2000 showing slightly decreased sensitivity for detection of viral loads close to the lower limit of quantitation. Follow-up of patients with low-level viral loads revealed that some of those represent single viral blips; however, a significant portion of these patients have intermittent or persistent low-positive viremia. We conclude that CAP/CTM v2.0 is an accurate and reliable assay for HIV-1 viral load monitoring.

Evaluation of blood collection filter papers for HIV-1 DNA PCR

BackgroundThe collection of dried blood spots (DBS) on Whatman 903 cards has facilitated for years the detection of HIV-1 in infants by DNA PCR as early as 4–6 weeks after birth in resource-limited settings (RLS), but alternate blood collection devices are proving to be necessary. ObjectivesThe qualitative detection of HIV-1 DNA by PCR from DBS prepared on three commercially available blood collection cards was evaluated at the Centers for Disease Control and Prevention (CDC) and in four laboratories in Africa. Study designDBS were prepared on Ahlstrom grade 226, Munktell TFN and Whatman 903, and stored under a variety of conditions. DBS were stored at ambient temperature (RT), 37°C with high humidity, and −20°C for varying lengths of time. The presence of HIV-1 DNA was tested using Roche Amplicor HIV-1 DNA (v 1.5) weekly for 4 weeks and at weeks 8 and 12 (RT and 37°C), at weeks 4, 8, and 18 (−20°C) of storage. DBS specimens were also tested after international shipment at RT. In addition, after nearly 3 years storage at −20°C, DBS were also evaluated independently using the COBAS Ampliprep/TaqMan HIV-1 Qual and Abbott RealTime HIV-1 Qualitative tests. ResultsHIV-1 DNA was detected equally well on the three blood collection cards regardless of storage conditions and PCR assay. ConclusionsAhlstrom 226 and Munktell TFN papers were comparable to Whatman 903 for HIV-1 DNA detection and may be considered as optional blood collection devices in resource-limited countries.