Supersensitive Viral Load Assay in Predicting CD4-Guided Treatment Failure.
Ontology highlight
ABSTRACT:
SUBMITTER: Langford S
PROVIDER: S-EPMC2678812 | biostudies-literature | 2008
REPOSITORIES: biostudies-literature
Publications
Supersensitive Viral Load Assay in Predicting CD4-Guided Treatment Failure.
Langford Simone S Gayet-Ageron Angele A Duncombe Chris C Jupimai Thidarat T Mahanontharit Apicha A Kiertiburanakul Sasisopin S Munsakul Warangkana W Ruxrungtham Kiat K Hirschel Bernard B Ananworanich Jintanat J
The open virology journal 20081016
In HIV patients who discontinue highly active antiretroviral therapy (HAART), the degree of HIV RNA suppression at the time of treatment interruption may predict success of re-treatment after the interruption (STI). A case-control substudy of the Staccato trial in Thailand included CD4-guided STI subjects with HIV RNA > 50 copies /ml (virological failure cases, n=11) and HIV RNA < 50 copies/ml (controls, n=22) after 12-24 weeks of HAART re-treatment following a median of 2 STI cycles. Controls w ...[more]
Similar Datasets
Project description:BackgroundCD4 cell count has been identified to be an essential component in monitoring HIV treatment outcome. However, CD4 cell count monitoring sometimes fails to predict virological failure resulting in unnecessary switch of treatment lines which causes drug resistance and limitations of treatment options. This study assesses the use of both viral load (HIV RNA) and CD4 cell count in the monitoring of HIV/AIDS progression.MethodsTime-homogeneous Markov models were fitted, one on CD4 cell count monitoring and the other on HIV RNA monitoring. Effects of covariates; gender, age, CD4 baseline, HIV RNA baseline and adherence to treatment were assessed for each of the fitted models. Assessment of the fitted models was done using prevalence plots and the likelihood ratio tests. The analysis was done using the "msm" package in R.ResultsResults from the analysis show that viral load monitoring predicts deaths of HIV/AIDS patients better than CD4 cell count monitoring. Assessment of the fitted models shows that viral load monitoring is a better predictor of HIV/AIDS progression than CD4 cell count.ConclusionFrom this study one can conclude that although patients take more time to achieve a normal CD4 cell count and less time to achieve an undetectable viral load, once the CD4 cell count is normal, mortality risks are reduced. Therefore, both viral load monitoring and CD4 count monitoring can be used to provide useful information which can be used to improve life expectance of patients living with HIV. However, viral load monitoring is a better predictor of HIV/AIDS progression than CD4 cell count and hence viral load is deemed superior.
| S-EPMC6377778 | biostudies-literature
Project description:BackgroundInterventions aiming for an HIV cure would benefit from rapid elimination of virus after the onset of antiretroviral therapy (ART), by keeping the latent HIV reservoir small.SettingWe investigated HIV suppression in 312 perinatally infected infants starting ART within 6 months after birth from the EPPICC (European Pregnancy and Paediatric HIV Cohort Collaboration).MethodsTo better understand kinetic differences in HIV suppression among infants, we investigated their individual viral load (VL) decay dynamics. We identified VL decay patterns and determined times to viral suppression (TTS). For infants with strictly declining VLs (n = 188), we used parameter fitting methods to estimate baseline VLs, decay rates, and TTS. We subsequently identified the parameters determining TTS by linear modeling.ResultsThe majority of infants suppress HIV VL after the onset of ART. Some children experienced a long TTS due to an "erratic" VL decay pattern. We cannot exclude that this is partly due to treatment complications and subsequent treatment changes, but these children were characterized by significantly lower CD4 percentages (CD4%) at start of treatment compared with those with a "clean" VL decline. Focusing on this "clean" subset, the TTS could be predicted by mathematical modeling, and we identified baseline VL and CD4% as the major factors determining the TTS.ConclusionsAs VL steeply increases and CD4% constantly decreases in untreated HIV-infected infants, the progression of an HIV infection is largely determined by these 2 factors. To prevent a further disease progression, treatment should be initiated early after contracting HIV, which consequently shortens TTS.
| S-EPMC7147397 | biostudies-literature
Project description:BACKGROUND: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). METHODS: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. RESULTS: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. CONCLUSION: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.
| S-EPMC7259604 | biostudies-literature
Project description:BackgroundViral load (VL) is recommended for monitoring the response to highly active antiretroviral therapy (HAART) but is not routinely available in most low- and middle-income countries. The purpose of the study was to determine whether a CD4-based monitoring and switching strategy would provide a similar clinical outcome compared to the standard VL-based strategy in Thailand.Methods and findingsThe Programs for HIV Prevention and Treatment (PHPT-3) non-inferiority randomized clinical trial compared a treatment switching strategy based on CD4-only (CD4) monitoring versus viral-load (VL). Consenting participants were antiretroviral-naïve HIV-infected adults (CD4 count 50-250/mm(3)) initiating non-nucleotide reverse transcriptase inhibitor (NNRTI)-based therapy. Randomization, stratified by site (21 public hospitals), was performed centrally after enrollment. Clinicians were unaware of the VL values of patients randomized to the CD4 arm. Participants switched to second-line combination with confirmed CD4 decline >30% from peak (within 200 cells from baseline) in the CD4 arm, or confirmed VL >400 copies/ml in the VL arm. Primary endpoint was clinical failure at 3 years, defined as death, new AIDS-defining event, or CD4 <50 cells/mm(3). The 3-year Kaplan-Meier cumulative risks of clinical failure were compared for non-inferiority with a margin of 7.4%. In the intent to treat analysis, data were censored at the date of death or at last visit. The secondary endpoints were difference in future-drug-option (FDO) score, a measure of resistance profiles, virologic and immunologic responses, and the safety and tolerance of HAART. 716 participants were randomized, 356 to VL monitoring and 360 to CD4 monitoring. At 3 years, 319 participants (90%) in VL and 326 (91%) in CD4 were alive and on follow-up. The cumulative risk of clinical failure was 8.0% (95% CI 5.6-11.4) in VL versus 7.4% (5.1-10.7) in CD4, and the upper-limit of the one-sided 95% CI of the difference was 3.4%, meeting the pre-determined non-inferiority criterion. Probability of switch for study criteria was 5.2% (3.2-8.4) in VL versus 7.5% (5.0-11.1) in CD4 (p=0.097). Median time from treatment initiation to switch was 11.7 months (7.7-19.4) in VL and 24.7 months (15.9-35.0) in CD4 (p=0.001). The median duration of viremia >400 copies/ml at switch was 7.2 months (5.8-8.0) in VL versus 15.8 months (8.5-20.4) in CD4 (p=0.002). FDO scores were not significantly different at time of switch. No adverse events related to the monitoring strategy were reported.ConclusionsThe 3-year rates of clinical failure and loss of treatment options did not differ between strategies although the longer-term consequences of CD4 monitoring would need to be investigated. These results provide reassurance to treatment programs currently based on CD4 monitoring as VL measurement becomes more affordable and feasible in resource-limited settings.Trial registrationClinicalTrials.govNCT00162682 Please see later in the article for the Editors' Summary.
| S-EPMC3735458 | biostudies-literature
Project description: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.
| S-EPMC5527414 | biostudies-literature
Project description:Assays for classifying HIV infections as 'recent' or 'nonrecent' for incidence surveillance fail to simultaneously achieve large mean durations of 'recent' infection (MDRIs) and low 'false-recent' rates (FRRs), particularly in virally suppressed persons. The potential for optimizing recent infection testing algorithms (RITAs), by introducing viral load criteria and tuning thresholds used to dichotomize quantitative measures, is explored.The Consortium for the Evaluation and Performance of HIV Incidence Assays characterized over 2000 possible RITAs constructed from seven assays (Limiting Antigen, BED, Less-sensitive Vitros, Vitros Avidity, BioRad Avidity, Architect Avidity, and Geenius) applied to 2500 diverse specimens.MDRIs were estimated using regression, and FRRs as observed 'recent' proportions, in various specimen sets. Context-specific FRRs were estimated for hypothetical scenarios. FRRs were made directly comparable by constructing RITAs with the same MDRI through the tuning of thresholds. RITA utility was summarized by the precision of incidence estimation.All assays produce high FRRs among treated patients and elite controllers (10-80%). Viral load testing reduces FRRs, but diminishes MDRIs. Context-specific FRRs vary substantially by scenario - BioRad Avidity and Limiting Antigen provided the lowest FRRs and highest incidence precision in scenarios considered.The introduction of a low viral load threshold provides crucial improvements in RITAs. However, it does not eliminate nonzero FRRs, and MDRIs must be consistently estimated. The tuning of thresholds is essential for comparing and optimizing the use of assays. The translation of directly measured FRRs into context-specific FRRs critically affects their magnitudes and our understanding of the utility of assays.
| S-EPMC5024345 | biostudies-literature
Project description:Viral load (VL) measurements are critical to the proper management of HIV in developing countries. However, access to VL assays is limited by the high cost and complexity of existing assays. While there is a need for low cost VL assays, performance must not be compromised. Thus, new assays must be validated on metrics of limit of detection (LOD), accuracy, and dynamic range. Patient plasma samples from the Joint Clinical Research Centre in Uganda were de-identified and measured using both an existing VL assay (Abbott RealTime HIV-1) and our assay, which combines low cost reagents with a simplified method of RNA isolation termed Exclusion-Based Sample Preparation (ESP).71 patient samples with VLs ranging from <40 to >3,000,000 copies/mL were used to compare the two methods. We demonstrated equivalent LOD (~50 copies/mL) and high accuracy (average difference between methods of 0.08 log, R2 = 0.97). Using expenditures from this trial, we estimate that the cost of the reagents and consumables for this assay to be approximately $5 USD. As cost is a significant barrier to implementation of VL testing, we anticipate that our assay will enhance access to this critical monitoring test in developing countries.
| S-EPMC4667969 | biostudies-literature
Project description:A successful prophylactic vaccine is characterized by long-lived immunity, which is critically dependent on CD4 T cell-mediated helper signals. Indeed, most licensed vaccines induce antigen-specific CD4 T cell responses, in addition to high-affinity antibodies. However, despite the important role of CD4 T cells in vaccine design and natural infection, few studies have characterized HIV-specific CD4 T cells due to their preferential susceptibility to HIV infection. To establish at the population level the impact of HIV-specific CD4 T cells on viral control and define the specificity of HIV-specific CD4 T cell peptide targeting, we conducted a comprehensive analysis of these responses to the entire HIV proteome in 93 subjects at different stages of HIV infection. We show that HIV-specific CD4 T cell responses were detectable in 92% of individuals and that the breadth of these responses showed a significant inverse correlation with the viral load (P = 0.009, R = -0.31). In particular, CD4 T cell responses targeting Gag were robustly associated with lower levels of viremia (P = 0.0002, R = -0.45). Importantly, differences in the immunodominance profile of HIV-specific CD4 T cell responses distinguished HIV controllers from progressors. Furthermore, Gag/Env ratios were a potent marker of viral control, with a high frequency and magnitude of Gag responses and low proportion of Env responses associated with effective immune control. At the epitope level, targeting of three distinct Gag peptides was linked to spontaneous HIV control (P = 0.60 to 0.85). Inclusion of these immunogenic proteins and peptides in future HIV vaccines may act as a critical cornerstone for enhancing protective T cell responses.
| S-EPMC3255877 | biostudies-other
Project description:BackgroundThe lower limit of detection of the original Roche Amplicor HIV plasma viral load (pVL) assay (50 copies/mL) has defined HIV treatment success. The Amplicor assay, however, has been replaced by the Roche TaqMan assay(s). Changes to the limits of detection and calibration have not been validated for clinical utility. Sudden increases in the number of patients with detectable pVL have been reported following the introduction of the TaqMan version 1 assay.MethodsBetween October 2009 and April 2010 all routine pVL samples from British Columbia, Canada, with 40-250 copies/mL by TaqMan were re-tested by Amplicor (N = 1198). Subsequent short-term virological and resistance outcomes were followed in patients with unchanged therapy (N = 279; median 3.2 months follow-up).ResultsTaqMan and Amplicor values correlated poorly at low pVL values. Low-level pVL by TaqMan was not associated with impending short-term virological failure; only 17% of patients with 40-250 copies/mL by TaqMan had detectable pVL by Amplicor at follow-up. During the follow-up period only 20% of patients had an increase in pVL by TaqMan (median [IQR]: 80 [36-283] copies/mL). In addition, in ~2.4% of samples pVL was dramatically underestimated by TaqMan due to poor binding of the proprietary TaqMan primers.ConclusionsThe replacement of Amplicor with the TaqMan assay has altered the previously accepted definition of HIV treatment failure without any evidence to support the clinical relevance of the new definition. Given the systematic differences in measurement in the low pVL range the British Columbia HIV treatment guidelines now use a threshold of >250 copies/mL by TaqMan to define treatment failure.
| S-EPMC3427308 | biostudies-literature
Project description:INTRODUCTION:The goals of scale-up of antiretroviral therapy (ART) have expanded from prevention of morbidity and death to include prevention of transmission. Morbidity and mortality risk are associated with CD4 count; transmission risk depends on plasma viral load (VL). This study aimed to describe CD4 count and VL distributions among HIV-infected individuals in a South African township to gain insights into the potential impact of ART scale-up on community HIV transmission risk. METHODS:A random sample of 10% of the adult population was invited to attend an HIV testing service. Study procedures included a questionnaire, HIV testing, CD4 count, and VL testing. RESULTS:One thousand one hundred forty-four (88.0%) of 1300 randomly selected individuals participated in the study. Two hundred sixty tested positive, giving an HIV prevalence of 22.7% [95% confidence interval (CI): 20.3 to 25.3]. A third of all HIV-infected individuals (33.5%, 95% CI: 27.8 to 39.6) reported taking ART. The median CD4 count was 417 cells per microliter (interquartile range, 285-627); 33 (12.7%, 95% CI: 8.9 to 17.4) had a CD4 count of ?200 cells per microliter. VL measurements were available for 219 individuals (84.2%) and were undetectable in 72 (33.9%), >1500 copies per milliliter in 127 (58.0%) and >10,000 copies per milliliter in 96 (43.8%). Of those reporting they were receiving ART, 30.4% had a VL >1500 copies per milliliter compared with 58.0% of those reporting they were not receiving ART. CONCLUSIONS:A small proportion of those living with HIV in this community had a CD4 count of <200 cells per microliter; more than half had a VL high enough to be associated with considerable transmission risk. A substantial proportion of HIV-infected individuals remained at risk of transmitting HIV even after starting ART.
| S-EPMC4233323 | biostudies-literature