Abbott RealTime HIV-1 Assay Research Articles

Comparison of Roche TaqMan v.2.0, Abbott RealTime and Modified Abbott Residual Viremia Assays in Testing of Routine Samples for Viremia Monitoring in HIV Care

BackgroundRoutine HIV RNA clinical monitoring frequently reports virermia (VL) as detectable, quantifiable <50 or blips >50 c/mL. To assess whether the results represent true increases or just assay variability, we designed comparisons of the Roche COBAS AmpliPrep / COBAS TaqMan HIV-1 Test version 2.0 (TM) and the Abbott RealTime HIV-1 assay (RT) to a residual viremia (RV) assay with a limit of detection of 3 c/mL, the Modified Abbott Residual Viremia assay (MARV).MethodsHIV suppressed patients on stable therapy presenting for routine visits at the HIV clinic in Henry Ford Hospital (HFH) were prospectively enrolled. Blood samples and questionnaires were obtained at each visit. Paired plasma samples were processed and analyzed per manufacturer instructions; HFH clinical laboratory processed the samples using the TM assay and the McKinnon Research Laboratory performed the FDA approved RT assay and RV testing using the MARV assay. Parametric and non-parametric analyses were conducted as indicated.Results124 HIV patients are reported with a mean age of 51, mostly male (84%) and African American (64%). Mean CD4 cell counts were 661 cells/mm3. TM assay results for 196 plasma samples were not detectable (ND) 119 (61%), detectable (DT) 61 (31%) and quantifiable viremia (QV) >20 c/mL 16 (8%). 5 patients had QV over 50 c/mL. 60 tested patients (49.5%) had at least one sample either DT or QV. TM results were not correlated to CD4 cell counts, antiretrovirals, medical conditions or reported adherence (avg. 97%). 174 RT and 187 MARV paired tests were ND on 142 (81%) / 121 (65%), DT on 34 (17%) RT, and quantifiable in 0% / 34 (33%) of the samples respectively. Higher VL detection by the TM was shown compared with the RT (P = 0.005) and MARV (P < 0.001) assays. Mean QV by the MARV was 5.0 vs.. 55 c/mL on the TM assay (P < 0.001). VL for all assays trends correlated when compared for ND, DT and >20 copies/mL (P < 0.001). Bland-Altman plots show higher VL detected by TM as compared with MARV (P < 0.001) and good correlation between RT and MARV assays (P = 0.6).ConclusionHIV viremia is more frequently reported by TM assay as compared with the RT assay and was significantly higher than VL detected by the MARV assay. Over detection of VL by the TM assay may impact clinical decision making and increase cost of care.Disclosures J. Mckinnon, Abbott Molecular: Speaker’s Bureau, Grant recipient, Research grant and Speaker honorarium D. Lucic, Abbott Molecular: Employee, Salary

HIV-1 viral load measurement in venous blood and fingerprick blood using Abbott RealTime HIV-1 DBS assay

BackgroundHIV RNA suppression is a key indicator for monitoring success of antiretroviral therapy. From a logistical perspective, viral load (VL) testing using Dried Blood Spots (DBS) is a promising alternative to plasma based VL testing in resource-limited settings. ObjectivesTo evaluate the analytical and clinical performance of the Abbott RealTime HIV-1 assay using a fully automated one-spot DBS sample protocol. Study designLimit of detection (LOD), linearity, lower limit of quantitation (LLQ), upper limit of quantitation (ULQ), and precision were determined using serial dilutions of HIV-1 Virology Quality Assurance stock (VQA Rush University), or HIV-1-containing armored RNA, made in venous blood. To evaluate correlation, bias, and agreement, 497 HIV-1 positive adult clinical samples were collected from Ivory Coast, Uganda and South Africa. For each HIV-1 participant, DBS-fingerprick, DBS-venous and plasma sample results were compared. Correlation and bias values were obtained. The sensitivity and specificity were analyzed at a threshold of 1000 HIV-1 copies/mL generated using the standard plasma protocol. ResultsThe Abbott HIV-1 DBS protocol had an LOD of 839 copies/mL, a linear range from 500 to 1×107 copies/mL, an LLQ of 839 copies/mL, a ULQ of 1×107 copies/mL, and an inter-assay SD of ≤0.30 log copies/mL for all tested levels within this range. With clinical samples, the correlation coefficient (r value) was 0.896 between DBS-fingerprick and plasma and 0.901 between DBS-venous and plasma, and the bias was −0.07 log copies/mL between DBS-fingerprick and plasma and −0.02 log copies/mL between DBS-venous and plasma. The sensitivity of DBS-fingerprick and DBS-venous was 93%, while the specificity of both DBS methods was 95%. ConclusionThe results demonstrated that the Abbott RealTime HIV-1 assay with DBS sample protocol is highly sensitive, specific and precise across a wide dynamic range and correlates well with plasma values. The Abbott RealTime HIV-1 assay with DBS sample protocol provides an alternative sample collection and transfer option in resource-limited settings and expands the utility of a viral load test to monitor HIV-1 ART treatment for infected patients.

Field evaluation of an open and polyvalent universal HIV-1/SIVcpz/SIVgor quantitative RT-PCR assay for HIV-1 viral load monitoring in comparison to Abbott RealTime HIV-1 in Cameroon

With the increasing demand of HIV viral load (VL) tests in resource-limited countries (RLCs) there is a need for assays at affordable cost and able to quantify all known HIV-1 variants. VLs obtained with a recently developed open and polyvalent universal HIV-1/SIVcpz/SIVgor RT-qPCR were compared to Abbott RealTime HIV-1 assay in Cameroon. On 474 plasma samples, characterized by a wide range of VLs and a broad HIV-1 group M genetic diversity, 97.5% concordance was observed when using the lower detection limit of each assay. When using the threshold of 3.00 log10 copies/mL, according to WHO guidelines to define virological failure (VF) in RLCs, the concordance was 94.7%, 360/474 versus 339/474 patients were identified with VF with the new assay and Abbott RealTime HIV-1, respectively. Higher VLs were measured with the new assay, +0.47 log10 copies/mL (95% CI; 0.42-0.52) as shown with Bland-Altman analysis. Eleven samples from patients on VF with drug resistance were not detected by Abbott RealTime HIV-1 versus two only with the new assay. Overall, our study showed that the new assay can be easily implemented in a laboratory in RLCs with VL experience and showed good performance on a wide diversity of HIV-1 group M variants.

Performance Evaluation of the New HIV-1 Quantification Assay, Xpert HIV-1 Viral Load, on a Wide Panel of HIV-1 Variants.

To evaluate the quantification performance of the new Cepheid GeneXpert HIV-1 viral load assay, on a wide panel of HIV-1 variants. Clinical performance was evaluated relative to the Abbott RealTime HIV-1 assay on 285 HIV-1 seropositive samples selected to cover the assays quantification range (40 copies/mL-10,000,000 copies/mL), and included RNA undetectable or detected seropositive samples. The panel comprised 120 subtype B, 150 non-B, and 15 nontypable clinical samples; serial dilutions of 18 viral supernatants representative of the divergent viruses of HIV-1 groups N, O, and P were also tested. Based on samples selected according to the Abbott assay viral loads (VL), the Cepheid assay detected or quantified 222/285 (78%) samples and the Abbott assay 240/285 (84%). Xpert yielded VLs for 162 (76%) of the 213 quantifiable samples with Abbott. This difference corresponded to 51 samples with VL >40 copies/mL by the Abbott assay (all below 200 copies/mL) but detected (n = 40) or undetectable (n = 11) by the Cepheid assay. VL of samples quantifiable by both assays (n = 162) showed very strong correlation, with a Spearman correlation coefficient of 0.985 and a Bland-Altman's mean of differences of -0.01. Performance for quantification of the non-M samples showed very good correlation, with significantly higher values with Cepheid for the group N and 2 group O samples. Our study showed that the Xpert HIV-1 VL assay offered very good performance for detection and quantification of the current HIV-1 genetic diversity; differences reported at the threshold could be an issue and requires further evaluations. The practicability of this new assay makes it suitable for low-income countries, where it could facilitate and improve follow-up of patients, as well as for high-income regions.

Multi-site clinical evaluation of the Xpert® HIV-1 viral load assay

BackgroundThe most important reason for measuring HIV-1 viral load (VL) is to monitor the effectiveness of antiretroviral therapy (ART), both for the initial therapeutic response and sustained responses. Maintaining low or undetectable HIV-1 VL levels can reduce both the risks of progression to AIDS and transmission of infection to others. ObjectivesTo evaluate the diagnostic accuracy of Xpert® HIV-1 Viral Load (VL) assay compared to the Abbott RealTime HIV-1 assay, including assessing specificity by testing plasma specimens from confirmed HIV-1 negative blood donors. Study designSubjects were enrolled from 4 participating sites, 2 in Europe and 2 in the USA. Fresh plasma samples were tested prospectively, while frozen plasma samples were collected prospectively, and tested retrospectively after selection of specimens to cover the assay’s quantification range (40cp/mL–10,000,000 cp/mL). Eligibility criteria included a clinician ordered HIV-1 VL test from a confirmed HIV-1 positive adult (≥18 years) with a known antiviral treatment status. Exclusion criteria included previous enrollment in this study or improper specimen collection. Human blood donor specimens determined to be HIV-1 negative by standard blood bank antibody and nucleic acid amplification methods were used to assess specificity. ResultsOf the 764 specimens collected, 752 were eligible for inclusion but 5 were not tested by the Xpert, leaving 747 specimens tested (28.2% from females and 71.8% from males). Valid results were obtained for 724/747 (96.9%) specimens tested using the Xpert HIV-1 VL assay. The Xpert HIV-1 VL assay detected or quantified 568/724 (78.5%) specimens, while the RealTime HIV-1 assay detected or quantified 559/724 (77.2%). Of the 724 specimens tested by both assays, 390 were quantified by both assays and showed strong correlation: r=0.9847, with an R2=0.9696. Bland-Altman analysis showed good agreement between the two assays (381/390; 97.7%) with a distribution within 0.5 log10 cp/mL centered around zero. Xpert yielded VLs for 393 (80%) of the 494 quantifiable samples by Abbott. VLs of those specimens quantified by one of the assays, and either detected but not quantified or not detected by the other assay were all <170cp/mL. Specificity of the Xpert assay was found to be 100% (109/109), 95% CI: 96.7–100.0. ConclusionVery good correlation was seen between the Xpert HIV-1 VL and Abbott RealTime HIV-1 assays, with added benefits for Xpert HIV-1 VL of: (1) lot-to-lot consistency traceable to WHO International Standard, (2) requiring both high and low level internal controls to be in range to have a valid result, (3) use of a single HIV-1 target for PCR and (4) faster turn-around-time for results, no need to wait to do batch testing of specimens. In summary, Xpert HIV-1 VL generated accurate VL results that if implemented could allow for actionable and timely treatment decisions during the same clinic visit. This scenario could reduce the loss to follow up often seen when these test results take days to weeks to become available to the clinician and patient.

Application of Radial Basis Function Network Tool for Correlation of CD4+ Count with Plasma Viral Load in HIV-Seropositive Individuals.

Human Immunodeficiency Virus (HIV) infects and cripples the immune system of the body. The two important marker CD4+T cells and Plasma viral load are crucial not only in understanding the disease progression but also in starting the antiretroviral therapy. A lot of research is going on in understanding the dynamic nature of HIV. To find the correlation between CD4+ count and Plasma Viral Load (PVL) measured by two different technologies; with the help of correlation technique in conjunction with the three dimensional HIV model with a purpose of establishing a mathematical model between the CD4+ cells and PVL using a sinusoidal function as well as Radial Basis Function (RBF) neural network. Plasma Viral Load were determined by two different methods viz Exavir Cavidi(TM) and Abbott Real time HIV-1 assay and then they were correlated with the CD4+ count with the help of computational intelligence in predicting viral load. It was found that there exists a positive correlation between the CD4+ cells and viral loads. A correlation value of 0.4082 and 0.3652 was observed between CD4+ cells and viral measured using Exavir Cavidi(TM) and Abbott Real time HIV-1 assay respectively. The existence of positive correlation had helped us to understand the nature and dynamic of the existence of HIV and how the CD4 + and PVL act.

Measurement of viral load by the automated Abbott real-time HIV-1 assay using dried blood spots collected and processed in Malawi and Mozambique.

The use of dried blood spots (DBS) for HIV-1 viral load quantification can greatly improve access to viral monitoring for HIV-infected patients receiving treatment in resource-limited settings. To evaluate and validate HIV viral load measurement from DBS in sub-Saharan Africa, with a reliable, all-automated, standard commercial assay such as the Abbott m2000. A total of 277 DBS were collected in different health centres in Malawi and Mozambique and analysed for viral load determination using the Abbott m2000 assay with the corresponding plasma samples as gold standard. Samples were extracted using the m2000SP automatic extractor and then processed as the plasma samples using the specific 1.0 mL HIV-RNA DBS protocol. Among samples with detectable HIV-RNA the correlation between viral load obtained from the paired 131 plasma and DBS samples was high (r=0.946). Overall, viral load values between DBS and plasma differed by less than 0.5 log unit in 90.1% of cases and by less than 1 log unit in 100% of cases. Using a threshold of 1 000 copies/mL (defining virological failure in resource-limited settings), sensitivity was 94.2% and specificity 98.6%, and both positive and negative predictive values were high (98.5% and 94.5%, respectively). DBS extracted and processed using the Abbott automated system can be reliably used in resource-limited setting to diagnose virological failure.

Comparison of the bioMérieux NucliSENS EasyQ HIV-1 v2.0–HIV-1 RNA quantification assay versus Abbott RealTime HIV-1 and Roche Cobas TaqMan HIV-1 v2.0 on current epidemic HIV-1 variants

BackgroundAn improved version of the bioMérieux NucliSENS® EasyQ® HIV-1 v2.0 has been introduced to overcome the underquantification observed with previous versions, especially with non-B HIV-1 subtypes. ObjectivesComparing bioMérieux NucliSENS® EasyQ® HIV-1 v2.0 versus Roche Cobas CA/CTM v2.0 and Abbott RealTime HIV-1 assays for HIV-1 group M and non-M (N, O, P) viral load measurement. Study designThe three assays were tested in parallel on 103HIV-1 group M plasma samples, and on non-group M HIV-1 culture supernatants. ResultsValues obtained for the 103HIV-1 group M plasma samples tested with bioMérieux assay showed good overall correlation compared to the 2 others. The Roche Cobas assay gave higher values than the bioMérieux assay, while Abbott and bioMérieux both displayed similar results. However, analysis showed a wider dispersion in results when comparing the bioMérieux NucliSENS® EasyQ® HIV-1 v2.0 and the other 2 techniques. All data taken into account, we observed frequent discrepancies in quantification, of the plasma samples and major differences above 1log in 10/72 (13.8%). The quantification of non-M HIV groups in culture supernatant has shown variable results, with better quantification of HIV-O and of HIV-N respectively with the Abbott assay and the bioMérieux assay. ConclusionsThe bioMérieux NucliSENS® EasyQ® HIV-1 v2.0 showed improved sensitivity to non-B HIV-M subtypes compared to previous versions. Notwithstanding, we observed frequent discrepancies and a wide dispersion in results when comparing bioMérieux NucliSENS® EasyQ® HIV-1 v2.0 and the other 2 techniques.

Implementation and Operational Research: Correlates of Adherence and Treatment Failure Among Kenyan Patients on Long-term Highly Active Antiretroviral Therapy.

Universal access to highly active antiretroviral therapy (HAART) is still elusive in most developing nations. We asked whether peer support influenced adherence and treatment outcome and if a single viral load (VL) could define treatment failure in a resource-limited setting. A multicenter longitudinal and cross-sectional survey of VL, CD4 T cells, and adherence in 546 patients receiving HAART for up to 228 months. VL and CD4 counts were determined using m2000 Abbott RealTime HIV-1 assay and FACS counters, respectively. Adherence was assessed based on pill count and on self-report. Of the patients, 55.8%, 22.2%, and 22% had good, fair, and poor adherence, respectively. Adherence, peer support, and regimen, but not HIV disclosure, age, or gender, independently correlated with VL and durability of treatment in a multivariate analysis (P < 0.001). Treatment failure was 35.9% using sequential VL but ranged between 27% and 35% using alternate single VL cross-sectional definitions. More patients failed stavudine (41.2%) than zidovudine (37.4%) or tenofovir (28.8%, P = 0.043) treatment arms. Peer support correlated positively with adherence (χ(2), P < 0.001), with nonadherence being highest in the stavudine arm. VL before the time of regimen switch was comparable between patients switching and not switching treatment. Moreover, 36% of those switching still failed the second-line regimen. Weak adherence support and inaccessible VL testing threaten to compromise the success of HAART scale-up in Kenya. To hasten antiretroviral therapy monitoring and decision making, we suggest strengthening patient-focused adherence programs, optimizing and aligning regimen to WHO standards, and a single point-of-care VL testing when multiple tests are unavailable.

Healthy HIV-1-infected individuals on highly active antiretroviral therapy harbor HIV-1 in their alveolar macrophages.

In a prospective cross-sectional study we quantified HIV viral load within the alveolar macrophage in a cohort of healthy HIV-infected subjects who did not have medical comorbidities or smoke cigarettes to determine if alveolar macrophage proviral DNA was associated with alveolar macrophage phagocytic immune dysfunction. We enrolled 23 subjects who underwent bronchoscopy and bronchoalveolar lavage. Alveolar macrophages were isolated and HIV-1 RNA was quantified in the cells using the Abbott RealTime HIV-1 Assay. Proviral DNA was qualitatively measured using a modified version of the HIV-1 RNA assay. Phagocytosis measured by incubating alveolar macrophages with FITC-labeled Staphylococcus aureus and determining fluorescence with a Zeiss inverted microscope. Phagocytic index was calculated as (% positive cells × mean channel fluorescence)/100. Sixteen subjects had (+) proviral DNA and seven had (-) proviral DNA in their alveolar macrophages. Of all subjects 100% in both groups were on highly active antiretroviral therapy (HAART). The median plasma viral load was 0 in both groups. HIV-1-infected subjects with (+) proviral DNA in their alveolar macrophages had a significantly lower median alveolar macrophage phagocytic index compared to those with (-) proviral DNA in their alveolar macrophages [11.8 (IQR 4.8-39.0) vs. 64.9 (IQR 14.0-166.0), p = 0.05]. Alveolar macrophages harbor HIV even in otherwise healthy subjects with undetectable plasma viral loads, representing a potential reservoir for the virus. In addition, HIV viral replication within the macrophage may impair phagocytosis and other immune functions in the lung, leading to an increased risk for lung infection.

Difference in factors associated with low-level viraemia and virological failure: results from the Austrian HIV Cohort Study.

IntroductionFor some patients, it remains a challenge to achieve complete virological suppression which is the goal of antiretroviral therapy (ART). Identifying factors associated with low-level viraemia (LLV) and virological failure (VF) under ART might help to optimize management of these patients.Materials and MethodsWe investigated patients from the Austrian HIV Cohort Study receiving unmodified ART for >6 months with two nucleoside reverse-transcriptase inhibitors (NRTIs) with either a non-nucleoside reverse-transcriptase inhibitor (NNRTI) or a boosted protease inhibitor (PI) or an integrase inhibitor (INSTI) between 1 July 2012 and 1 July 2013 with at least one viral load (VL) measurement below the limit of detection (BLD) or below level of quantification (BLQ) in their treatment history. VF was defined as HIV-RNA levels ≥200 copies/mL and all other quantifiable measurements were classified as LLV. Factors associated with LLV and VF compared to BLD and BLQ were identified by using logistic regression models.ResultsOf the 2,276 patients analyzed, 1,972 (86.6%) were BLD or BLQ, 222 (9.8%) showed LLV and 82 (3.6%) had VF. A higher risk for LLV and VF was found in patients with ART interruptions and in patients with boosted PI therapy. The risk for LLV and VF was lower in patients from a centre which uses Abbott RealTime HIV-1 assay compared to the other centres measuring VL by the Roche Cobas AmpliPrep/Cobas TaqMan 2.0. A higher risk for LLV but not for VF was found in patients with a higher VL before ART and shorter ART duration. A higher risk for VF but not for LLV was found in patients of younger age, originating from a high prevalence country, with a lower CD4 count and in male injecting drug users.ConclusionsThis study of well-defined patients on stable ART over a period of more than six months gives insights into the different factors associated with LLV and VF. In patients with VF, factors associated with adherence play a prominent role, whereas in patients with LLV, the biology of viral replication comes additionally into effect. Despite its observational design, it has implications for patient management and forms the basis for future outcome studies.

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.

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

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

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.

Co-infection: new battlegrounds in HIV/AIDS

Co-infection: new battlegrounds in HIV/AIDS

Measuring the Unknown

Measuring the Unknown

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.