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Gray ER, Bain R, Varsaneux O, Peeling RW, Stevens MM, McKendry RA. p24 revisited: a landscape review of antigen detection for early HIV diagnosis. AIDS 2018; 32:2089-2102. [PMID: 30102659 PMCID: PMC6139023 DOI: 10.1097/qad.0000000000001982] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
: Despite major advances in HIV testing, early detection of infection at the point of care (PoC) remains a key challenge. Although rapid antibody PoC and laboratory-based nucleic acid amplification tests dominate the diagnostics market, the viral capsid protein p24 is recognized as an alternative early virological biomarker of infection. However, the detection of ultra-low levels of p24 at the PoC has proven challenging. Here we review the landscape of p24 diagnostics to identify knowledge gaps and barriers and help shape future research agendas. Five hundred and seventy-four research articles to May 2018 that propose or evaluate diagnostic assays for p24 were identified and reviewed. We give a brief history of diagnostic development, and the utility of p24 as a biomarker in different populations such as infants, the newly infected, those on preexposure prophylaxis and self-testers. We review the performance of commercial p24 assays and consider elements such as immune complex disruption, resource-poor settings, prevalence, and assay antibodies. Emerging and ultrasensitive assays are reviewed and show a number of promising approaches but further translation has been limited. We summarize studies on the health economic benefits of using antigen testing. Finally, we speculate on the future uses of high-performance p24 assays, particularly, if available in self-test format.
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Affiliation(s)
- Eleanor R Gray
- London Centre for Nanotechnology, Faculty of Maths and Physical Sciences, University College London
| | - Robert Bain
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London
| | | | | | - Molly M Stevens
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London
| | - Rachel A McKendry
- London Centre for Nanotechnology, Faculty of Maths and Physical Sciences, University College London
- Division of Medicine, University College London, London, UK
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Towards an ultra-rapid smartphone- connected test for infectious diseases. Sci Rep 2017; 7:11971. [PMID: 28931860 PMCID: PMC5607310 DOI: 10.1038/s41598-017-11887-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 08/23/2017] [Indexed: 12/18/2022] Open
Abstract
The development is reported of an ultra-rapid, point-of-care diagnostic device which harnesses surface acoustic wave (SAW) biochips, to detect HIV in a finger prick of blood within 10 seconds (sample-in-result-out). The disposable quartz biochip, based on microelectronic components found in every consumer smartphone, is extremely fast because no complex labelling, amplification or wash steps are needed. A pocket-sized control box reads out the SAW signal and displays results electronically. High analytical sensitivity and specificity are found with model and real patient blood samples. The findings presented here open up the potential of consumer electronics to cut lengthy test waiting times, giving patients on the spot access to potentially life-saving treatment and supporting more timely public health interventions to prevent disease transmission.
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Fransen K, de Baetselier I, Rammutla E, Ahmed K, Owino F, Agingu W, Venter G, Deese J, Van Damme L, Crucitti T. Detection of new HIV infections in a multicentre HIV antiretroviral pre-exposure prophylaxis trial. J Clin Virol 2017; 93:76-80. [PMID: 28351689 DOI: 10.1016/j.jcv.2017.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 03/12/2017] [Accepted: 03/15/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Monthly specimens collected from FEM-PrEP-a Phase III trial [1] were investigated for the detection of acute HIV (AHI) infection. OBJECTIVES To evaluate the efficiency of the study-specific HIV algorithm in detecting AHI, and the performance of each of the serological and molecular tests used in diagnosing new infections, and their contribution to narrowing the window period. STUDY DESIGN A total of 83 pre-seroconversion specimens from 61 seroconverters from the FEM-PrEP trial were further analyzed in a sub-study. During the trial, HIV seroconversion was diagnosed on site using a testing algorithm with simple/rapid tests (SRTs) and confirmed with a gold standard testing algorithm (see short communication: Fig. 1). The infection date was determined more accurately by the use of standard ELISAs and Nucleic Acid Amplification Tests (NAAT) in a look-back procedure. For this sub-study, the international central laboratory repeated the study algorithm using SRTs. RESULTS A total of 83 pre-seroconversions specimens from 61 seroconverters were analyzed in a look-back procedure. RNA was detected in 35/61 seroconverters at the visit before the seroconversion visit as determined at the study sites. Four seroconversion dates were inaccurate at one study site as the international central laboratory detected the HIV infection one visit earlier using the same test algorithm. Using the gold standard, an additional seroconversion was detected at an earlier visit. The combined antigen/antibody and the single antigen test had a higher sensitivity compared to the SRTs in detecting acute infections. CONCLUSIONS In the FEM-PrEP trial, the international central laboratory detected a small number of seroconversions one month earlier than the study sites using the same study algorithm. Standard tests are still the most sensitive tests in detecting pre-seroconversion or acute HIV infection, but they are costly, time consuming and not recommended for use on-site in a clinical trial.
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Affiliation(s)
| | | | | | - Khatija Ahmed
- Setshaba Research Centre, Soshanguve, Pretoria, South Africa
| | | | - Walter Agingu
- Impact Research and Development Organization, Kisumu, Kenya
| | | | | | - Lut Van Damme
- FHI 360, Durham, NC, USA; Bill and Melinda Gates Foundation, Seattle, Washington, USA
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Kurdekar AD, Chunduri LAA, Chelli SM, Haleyurgirisetty MK, Bulagonda EP, Zheng J, Hewlett IK, Kamisetti V. Fluorescent silver nanoparticle based highly sensitive immunoassay for early detection of HIV infection. RSC Adv 2017. [DOI: 10.1039/c6ra28737a] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Fluorescent silver nanoparticles have been employed in an immunoassay to detect HIV p24 antigen with high sensitivity in the linear range of 10–1000 pg mL−1.
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Affiliation(s)
- Aditya Dileep Kurdekar
- Laboratories for Nanoscience and Nanotechnology Research
- Department of Physics
- Sri Sathya Sai Institute of Higher Learning
- Puttaparthi 515134
- India
| | - L. A. Avinash Chunduri
- Laboratories for Nanoscience and Nanotechnology Research
- Department of Physics
- Sri Sathya Sai Institute of Higher Learning
- Puttaparthi 515134
- India
| | - Sai Manohar Chelli
- Department of Chemistry
- Sri Sathya Sai Institute of Higher Learning
- Puttaparthi 515134
- India
| | - Mohan Kumar Haleyurgirisetty
- Laboratory of Molecular Virology
- Center for Biologics Evaluation and Research (CBER)
- Food and Drug Administration
- Silver Spring
- USA
| | | | - Jiwen Zheng
- Division of Biology
- Chemistry and Material Science
- Office of Science and Engineering laboratories
- Center for Devices and Radiological Health (CDRH)
- Food and Drug Administration
| | - Indira K. Hewlett
- Laboratory of Molecular Virology
- Center for Biologics Evaluation and Research (CBER)
- Food and Drug Administration
- Silver Spring
- USA
| | - Venkataramaniah Kamisetti
- Laboratories for Nanoscience and Nanotechnology Research
- Department of Physics
- Sri Sathya Sai Institute of Higher Learning
- Puttaparthi 515134
- India
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Increased Sensitivity of HIV-1 p24 ELISA Using a Photochemical Signal Amplification System. J Acquir Immune Defic Syndr 2015; 70:109-14. [PMID: 26090753 DOI: 10.1097/qai.0000000000000726] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND In this study we describe a photochemical signal amplification method (PSAM) for increasing of the sensitivity of enzyme-linked immunosorbent assay (ELISA) for determination of HIV-1 p24 antigen. The photochemical signal amplification method is based on an autocatalytic photochemical reaction of a horseradish peroxidase (HRP) substrate, orthophenylenediamine (OPD). METHODS To compare the performance of PSAM-boosted ELISA with a conventional colorimetric ELISA for determination of HIV-1 p24 antigen we employed a PerkinElmer HIV-1 p24 ELISA kit, using conventional ELISA alongside ELISA + PSAM. RESULTS In the present study, we show that PSAM technology allows one to increase the analytical sensitivity and dynamic range of a commercial HIV-1 p24 ELISA kit, with and without immune-complex disruption, by a factor of approximately 40-fold. CONCLUSIONS ELISA + PSAM is compatible with commercially available microtiter plate readers, requires only an inexpensive illumination device, and the PSAM amplification step takes no longer than 15 min. This method can be used for both commercially available and in-house ELISA tests, and has the advantage of being considerably simpler and less costly than alternative signal amplification methods. This method can be used for both commercially available and in-house ELISA tests, and has the advantage of being considerably simpler and less costly than alternative signal amplification methods.
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Vetter BN, Orlowski V, Fransen K, Niederhauser C, Aubert V, Brandenberger M, Ciardo D, Dollenmaier G, Klimkait T, Regenass S, Schmid P, Schottstedt V, Suter-Riniker F, Yerly S, Shah C, Böni J, Schüpbach J. Generation of a recombinant Gag virus-like-particle panel for the evaluation of p24 antigen detection by diagnostic HIV tests. PLoS One 2014; 9:e111552. [PMID: 25343245 PMCID: PMC4208835 DOI: 10.1371/journal.pone.0111552] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 09/28/2014] [Indexed: 02/07/2023] Open
Abstract
Background Detection of HIV-1 p24 antigen permits early identification of primary HIV infection and timely intervention to limit further spread of the infection. Principally, HIV screening should equally detect all viral variants, but reagents for a standardised test evaluation are limited. Therefore, we aimed to create an inexhaustible panel of diverse HIV-1 p24 antigens. Methods We generated a panel of 43 recombinantly expressed virus-like particles (VLPs), containing the structural Gag proteins of HIV-1 subtypes A-H and circulating recombinant forms (CRF) CRF01_AE, CRF02_AG, CRF12_BF, CRF20_BG and group O. Eleven 4th generation antigen/antibody tests and five antigen-only tests were evaluated for their ability to detect VLPs diluted in human plasma to p24 concentrations equivalent to 50, 10 and 2 IU/ml of the WHO p24 standard. Three tests were also evaluated for their ability to detect p24 after heat-denaturation for immune-complex disruption, a pre-requisite for ultrasensitive p24 detection. Results Our VLP panel exhibited an average intra-clade p24 diversity of 6.7%. Among the 4th generation tests, the Abbott Architect and Siemens Enzygnost Integral 4 had the highest sensitivity of 97.7% and 93%, respectively. Alere Determine Combo and BioRad Access were least sensitive with 10.1% and 40.3%, respectively. Antigen-only tests were slightly more sensitive than combination tests. Almost all tests detected the WHO HIV-1 p24 standard at a concentration of 2 IU/ml, but their ability to detect this input for different subtypes varied greatly. Heat-treatment lowered overall detectability of HIV-1 p24 in two of the three tests, but only few VLPs had a more than 3-fold loss in p24 detection. Conclusions The HIV-1 Gag subtype panel has a broad diversity and proved useful for a standardised evaluation of the detection limit and breadth of subtype detection of p24 antigen-detecting tests. Several tests exhibited problems, particularly with non-B subtypes.
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Affiliation(s)
- Beatrice N. Vetter
- Swiss National Center for Retroviruses (SNCR), Institute of Medical Virology, University of Zürich, Zürich, Switzerland
- * E-mail:
| | - Vanessa Orlowski
- Swiss National Center for Retroviruses (SNCR), Institute of Medical Virology, University of Zürich, Zürich, Switzerland
| | - Katrien Fransen
- Institute of Tropical Medicine (ITG), Clinical Science, Antwerp, Belgium
| | | | - Vincent Aubert
- University Hospital, Service of Immunology and Allergy, CHUV, Lausanne, Switzerland
| | | | | | | | - Thomas Klimkait
- Department Biomedicine, Haus Petersplatz, University of Basel, Basel, Switzerland
| | | | - Patrick Schmid
- Department of Infectious Diseases, Cantonal Hospital St. Gallen (KSSG), St. Gallen, Switzerland
| | | | | | - Sabine Yerly
- University Hospitals (HUG), Laboratory of Virology, Genève, Switzerland
| | - Cyril Shah
- Swiss National Center for Retroviruses (SNCR), Institute of Medical Virology, University of Zürich, Zürich, Switzerland
| | - Jürg Böni
- Swiss National Center for Retroviruses (SNCR), Institute of Medical Virology, University of Zürich, Zürich, Switzerland
| | - Jörg Schüpbach
- Swiss National Center for Retroviruses (SNCR), Institute of Medical Virology, University of Zürich, Zürich, Switzerland
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He J, Evers DL, O'Leary TJ, Mason JT. Immunoliposome-PCR: a generic ultrasensitive quantitative antigen detection system. J Nanobiotechnology 2012; 10:26. [PMID: 22726242 PMCID: PMC3466442 DOI: 10.1186/1477-3155-10-26] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 06/22/2012] [Indexed: 11/10/2022] Open
Abstract
Background The accurate quantification of antigens at low concentrations over a wide dynamic range is needed for identifying biomarkers associated with disease and detecting protein interactions in high-throughput microarrays used in proteomics. Here we report the development of an ultrasensitive quantitative assay format called immunoliposome polymerase chain reaction (ILPCR) that fulfills these requirements. This method uses a liposome, with reporter DNA encapsulated inside and biotin-labeled polyethylene glycol (PEG) phospholipid conjugates incorporated into the outer surface of the liposome, as a detection reagent. The antigenic target is immobilized in the well of a microplate by a capture antibody and the liposome detection reagent is then coupled to a biotin-labeled second antibody through a NeutrAvidin bridge. The liposome is ruptured to release the reporter DNA, which serves as a surrogate to quantify the protein target using real-time PCR. Results A liposome detection reagent was prepared, which consisted of a population of liposomes ~120 nm in diameter with each liposome possessing ~800 accessible biotin receptors and ~220 encapsulated reporters. This liposome detection reagent was used in an assay to quantify the concentration of carcinoembryonic antigen (CEA) in human serum. This ILPCR assay exhibited a linear dose–response curve from 10-10 M to 10-16 M CEA. Within this range the assay coefficient of variance was <6 % for repeatability and <2 % for reproducibility. The assay detection limit was 13 fg/mL, which is 1,500-times more sensitive than current clinical assays for CEA. An ILPCR assay to quantify HIV-1 p24 core protein in buffer was also developed. Conclusions The ILPCR assay has several advantages over other immuno-PCR methods. The reporter DNA and biotin-labeled PEG phospholipids spontaneously incorporate into the liposomes as they form, simplifying preparation of the detection reagent. Encapsulation of the reporter inside the liposomes allows nonspecific DNA in the assay medium to be degraded with DNase I prior to quantification of the encapsulated reporter by PCR, which reduces false-positive results and improves quantitative accuracy. The ability to encapsulate multiple reporters per liposome also helps overcome the effect of polymerase inhibitors present in biological specimens. Finally, the biotin-labeled liposome detection reagent can be coupled through a NeutrAvidin bridge to a multitude of biotin-labeled probes, making ILPCR a highly generic assay system.
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Affiliation(s)
- Junkun He
- Biomedical Laboratory Research and Development Service, Veterans Health Administration, Washington, DC, USA
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Spacek LA, Lutwama F, Shihab HM, Summerton J, Kamya MR, Ronald A, Laeyendecker O, Quinn TC, Mayanja-Kizza H. Diagnostic accuracy of ultrasensitive heat-denatured HIV-1 p24 antigen in non-B subtypes in Kampala, Uganda. Int J STD AIDS 2011; 22:310-4. [PMID: 21680665 PMCID: PMC3260525 DOI: 10.1258/ijsa.2009.009363] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We evaluated the accuracy of heat-denatured, amplification-boosted ultrasensitive p24 assay (Up24) compared with reverse transcriptase polymerase chain reaction (RT-PCR). We tested 394 samples from Ugandans infected with HIV-1 non-B subtypes. We compared Up24 levels (HIV-1 p24 Core Profile enzyme-linked immunosorbent assay (ELISA), NEN Life Science Products) to RNA viral loads (Amplicor HIV-1 Monitor 1.5, Roche) by linear regression, and calculated sensitivity, specificity, positive and negative predictive values. Median viral load was 4.9 log10 copies/mL (interquartile range [IQR], 2.6-5.5); 114 samples (29%) were undetectable (<400 copies/mL). Sensitivity of the Up24 assay to detect viral load ≥400 copies/mL was 69%, specificity was 67%, and positive and negative predictive values were 84% and 47%, respectively. Sensitivity of Up24 was 90%, 80%, 68%, 62% and 45% to detect viral loads of >500,000, 250,000-500,000, 100,000-250,000, 50,000-100,000 and 400-50,000 copies/mL, respectively. In conclusion, when compared with RT-PCR for patients infected with non-B subtypes, the Up24 demonstrated limited sensitivity especially at low viral loads. Moreover, the Up24 was positive in 33% of samples deemed undetectable by RT-PCR, which may limit the use of the Up24 to detect viral suppression.
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Affiliation(s)
- L A Spacek
- Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA.
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Abstract
Currently, the majority of HIV-infected infants are found within limited-resource settings, where inadequate screening for HIV due to the lack of access to simple and affordable point-of-care tests impedes implementation of antiretroviral therapy. Here we report development of a low-cost dipstick p24 antigen assay using a visual readout format that can facilitate the diagnosis of HIV for infants in resource-poor conditions. A heat shock methodology was developed to optimize disruption of immune complexes present in the plasma of infected infants. The analytical sensitivity of the assay using recombinant p24 antigen is 50 pg/mL (2 pM) with whole virus detection as low as 42.5k RNA copies per milliliter plasma. In a blinded study comprising 51 archived infant samples from the Women and Infants Transmission Study, our assay demonstrated an overall sensitivity and specificity of 90% and 100%, respectively. In field evaluations of 389 fresh samples from South African infants, a sensitivity of 95% and specificity of 99% was achieved. The assay is simple to perform, requires minimal plasma volume (25 μL), and yields a result in less than 40 minutes making it ideal for implementation in resource-limited settings.
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Stewart P, Cachafeiro A, Napravnik S, Eron JJ, Frank I, van der Horst C, Bosch RJ, Bettendorf D, Bohlin P, Fiscus SA. Performance characteristics of the Cavidi ExaVir viral load assay and the ultra-sensitive P24 assay relative to the Roche Monitor HIV-1 RNA assay. J Clin Virol 2010; 49:198-204. [PMID: 20832356 DOI: 10.1016/j.jcv.2010.07.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/21/2010] [Accepted: 07/30/2010] [Indexed: 10/19/2022]
Abstract
BACKGROUND The Cavidi viral load assay and the ultra-sensitive p24 antigen assay (Up24 Ag) have been suggested as more feasible alternatives to PCR-based HIV viral load assays for use in monitoring patients infected with HIV-1 in resource-limited settings. OBJECTIVES To describe the performance of the Cavidi ExaVir Load™ assay (version 2.0) and two versions of the Up24 antigen assay and to characterize their agreement with the Roche Monitor HIV-1 RNA assay (version 1.5). STUDY DESIGN Observational study using a convenience sample of 342 plasma specimens from 108 patients enrolled in two ACTG clinical trials to evaluate the performance characteristics of the Up24 Ag assay using two different lysis buffers and the Cavidi ExaVir Load™ assay. RESULTS In analysis of agreement with the Roche assay, the Cavidi assay demonstrated superiority to the Up24 Ag assays in accuracy and precision, as well as sensitivity, specificity, and positive and negative predictive values for HIV-1 RNA ≥ 400, ≥ 1000 and ≥ 5000 copies/mL. Logistic performance curves indicated that the Cavidi assay was superior to the Up24 assays for viral loads greater than 650 copies/mL. CONCLUSIONS The results suggest that the Cavidi ExaVir Load assay could be used for monitoring HIV-1 viral load in resource-limited settings.
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Affiliation(s)
- Paul Stewart
- The University of North Carolina at Chapel Hill, Department of Biostatistics, Chapel Hill, NC 27599-7420, USA. paul
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Wang S, Xu F, Demirci U. Advances in developing HIV-1 viral load assays for resource-limited settings. Biotechnol Adv 2010; 28:770-81. [PMID: 20600784 DOI: 10.1016/j.biotechadv.2010.06.004] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 06/21/2010] [Accepted: 06/21/2010] [Indexed: 12/23/2022]
Abstract
Commercial HIV-1 RNA viral load assays have been routinely used in developed countries to monitor antiretroviral treatment (ART). However, these assays require expensive equipment and reagents, well-trained operators, and established laboratory infrastructure. These requirements restrict their use in resource-limited settings where people are most afflicted with the HIV-1 epidemic. Inexpensive alternatives such as the Ultrasensitive p24 assay, the reverse transcriptase (RT) assay and in-house reverse transcription quantitative polymerase chain reaction (RT-qPCR) have been developed. However, they are still time-consuming, technologically complex and inappropriate for decentralized laboratories as point-of-care (POC) tests. Recent advances in microfluidics and nanotechnology offer new strategies to develop low-cost, rapid, robust and simple HIV-1 viral load monitoring systems. We review state-of-the-art technologies used for HIV-1 viral load monitoring in both developed and developing settings. Emerging approaches based on microfluidics and nanotechnology, which have potential to be integrated into POC HIV-1 viral load assays, are also discussed.
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Affiliation(s)
- ShuQi Wang
- Demirci Bio-Acoustic-MEMS in Medicine (BAMM) Laboratory, Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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Workman S, Wells SK, Pau CP, Owen SM, Dong XF, LaBorde R, Granade TC. Rapid detection of HIV-1 p24 antigen using magnetic immuno-chromatography (MICT). J Virol Methods 2009; 160:14-21. [DOI: 10.1016/j.jviromet.2009.04.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 03/27/2009] [Accepted: 04/01/2009] [Indexed: 02/07/2023]
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Biancotto A, Brichacek B, Chen SS, Fitzgerald W, Lisco A, Vanpouille C, Margolis L, Grivel JC. A highly sensitive and dynamic immunofluorescent cytometric bead assay for the detection of HIV-1 p24. J Virol Methods 2009; 157:98-101. [PMID: 19100289 DOI: 10.1016/j.jviromet.2008.11.013] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 11/13/2008] [Accepted: 11/24/2008] [Indexed: 11/16/2022]
Abstract
Nucleic acid measurements are used to follow HIV-1 viral load in clinical applications while p24 ELISA is commonly used to monitor HIV-1 replication in research settings. Current ELISA assays are expensive and offer a narrow dynamic measurement range. This report describes a simple, sensitive and inexpensive bead-based assay offering a wide dynamic measurement range. This cytometric bead assay allows the detection of p24 concentrations over 4 orders of magnitude from less than 0.4pg to up to 20,000pgml(-1) in a volume of 50microl and can be combined with other measurements.
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Affiliation(s)
- Angélique Biancotto
- Section on Intercellular Interactions, Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
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p24 as a predictor of mortality in a cohort of HIV-1-infected adults in rural Africa. J Acquir Immune Defic Syndr 2008; 48:345-9. [PMID: 18545150 DOI: 10.1097/qai.0b013e31817dc3d1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Implementation of antiretroviral treatment in sub-Saharan Africa requires efficient tools to monitor HIV patients. p24 measurements have been proposed as an alternative to HIV-RNA because of the low cost of reagents and equipment needed. Here, we evaluate p24 as a prognostic marker in a cohort of HIV-1-infected individuals in Zimbabwe. METHODS Treatment-naive HIV-1-infected individuals (n=198) from the Mupfure Schistosomiasis and HIV Cohort were followed until death or censoring (3-4.3 years). At baseline, p24, HIV-RNA, CD4 cell counts, and clinical staging (Centers for Disease Control and Prevention classification) were assessed. RESULTS p24 correlated with HIV-RNA (P<0.0001, R: 0.44). Ten percent of p24 but only 1% of HIV-RNA measurements was undetectable. p24 predicted Centers for Disease Control and Prevention category (P<0.001) stronger than CD4 count (P=0.34) in multivariate logistic regression. p24 predicted mortality in univariate Cox analysis (P<0.0001) and in multivariate analysis, but it was inferior to HIV-RNA and CD4 count. CONCLUSIONS This is the first study to evaluate the prognostic strength of p24 in an area with a predominance of HIV subtype C infections. p24 correlated with HIV-RNA and predicted clinical stage better than CD4 count. It predicted mortality in both univariate and multivariate analysis, but in multivariate analysis, it was inferior to HIV-RNA and CD4 count.
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Evaluation of the ultrasensitive human immunodeficiency virus type 1 (HIV-1) p24 antigen assay performed on dried blood spots for diagnosis of HIV-1 infection in infants. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 15:388-91. [PMID: 18057183 DOI: 10.1128/cvi.00265-07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The diagnostic accuracy of the modified p24 antigen assay performed on pediatric dried blood spots was evaluated. Samples analyzed within 6 weeks of collection yielded no false-positive results (specificity, 100%) and few false-negative results (sensitivity, 96.5% to 98.3%). Laboratory services with limited resources should assess this option for routine infant diagnosis.
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Mueller YM, Petrovas C, Do DH, Altork SR, Fischer-Smith T, Rappaport J, Altman JD, Lewis MG, Katsikis PD. Early establishment and antigen dependence of simian immunodeficiency virus-specific CD8+ T-cell defects. J Virol 2007; 81:10861-8. [PMID: 17670818 PMCID: PMC2045568 DOI: 10.1128/jvi.00813-07] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Differentiation and survival defects of human immunodeficiency virus (HIV)-specific CD8(+) T cells may contribute to the failure of HIV-specific CD8(+) T cells to control HIV replication. It is not known, however, whether simian immunodeficiency virus (SIV)-infected rhesus macaques show comparable defects in these virus-specific CD8(+) T cells or when such defects are established during infection. Peripheral blood cells from acutely and chronically infected rhesus macaques were stained ex vivo for memory subpopulations and examined by in vitro assays for apoptosis sensitivity. We show here that SIV-specific CD8(+) T cells from chronically SIV infected rhesus macaques show defects comparable to those observed in HIV infection, namely, a skewed CD45RA(-) CD62L(-) effector memory phenotype, reduced Bcl-2 levels, and increased levels of spontaneous and CD95-induced apoptosis of SIV-specific CD8(+) T cells. Longitudinal studies showed that the survival defects and phenotype are established early in the first few weeks of SIV infection. Most importantly, they appear to be antigen driven, since most probably the loss of epitope recognition due to viral escape results in the reversal of the phenotype and reduced apoptosis sensitivity, something we observed also for animals treated with antiretroviral therapy. These findings further support the use of SIV-infected rhesus macaques to investigate the phenotypic changes and apoptotic defects of HIV-specific CD8(+) T cells and indicate that such defects of HIV-specific CD8(+) T cells are the result of chronic antigen stimulation.
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Affiliation(s)
- Yvonne M Mueller
- Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
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17
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Tehe A, Maurice C, Hanson DL, Borget MY, Abiola N, Maran M, Yavo D, Tomasik Z, Böni J, Schüpbach J, Nkengasong JN. Quantification of HIV-1 p24 by a highly improved ELISA: An alternative to HIV-1 RNA based treatment monitoring in patients from Abidjan, Côte d’Ivoire. J Clin Virol 2006; 37:199-205. [PMID: 16973409 DOI: 10.1016/j.jcv.2006.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2006] [Revised: 07/18/2006] [Accepted: 08/02/2006] [Indexed: 11/23/2022]
Abstract
BACKGROUND Quantification of HIV-1 RNA remains difficult to implement in Africa. Simple and inexpensive tests for antiretroviral treatment (ART) monitoring are needed. OBJECTIVE To evaluate an HIV-1 p24 ELISA, which combines efficient virus disruption, heat-denaturation and signal amplification, in a West African setting. STUDY DESIGN Eighty-six HIV-1 infected patients from Abidjan, Côte d'Ivoire, were tested for p24, HIV-1 RNA, and CD4+ count at baseline, and twice within 8 months after ART initiation. RESULTS All patients responded to ART with a minimal HIV-1 RNA drop of 0.5 log(10) at first follow-up. Forty-one (47.7%) then rebounded >0.5 log(10) or persisted above 1000 copies/mL by week 24. The predicted baseline concentration of p24 corresponding to 100,000 copies/mL of HIV-1 RNA, above which ART is recommended, was 4546 fg/mL (95% confidence interval 3148-6566). A prediction model of virologic failure, occurring after an initial response to ART, correctly classified 84% of patients using baseline p24, p24 change on therapy, and achievement of undetectable p24 as explanatory variables. The model and further bootstrap evaluation suggested a good ability to discriminate between sustained or failing virologic response to ART. CONCLUSION HIV-1 p24 and RNA based-ART monitoring in a low-resource country dominated by HIV-1 CRF02 AG appeared comparable.
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Affiliation(s)
- Andre Tehe
- Projet RETRO-CI, Abidjan, Côte d'Ivoire.
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18
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Fiscus SA, Cheng B, Crowe SM, Demeter L, Jennings C, Miller V, Respess R, Stevens W. HIV-1 viral load assays for resource-limited settings. PLoS Med 2006; 3:e417. [PMID: 17032062 PMCID: PMC1592347 DOI: 10.1371/journal.pmed.0030417] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The authors discuss studies on the low-cost viral load assays that are currently available and their potential for use in resource-limited settings.
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Affiliation(s)
- Susan A Fiscus
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
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19
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Schüpbach J, Tomasik Z, Knuchel M, Opravil M, Günthard HF, Nadal D, Böni J. Optimized virus disruption improves detection of HIV-1 p24 in particles and uncovers a p24 reactivity in patients with undetectable HIV-1 RNA under long-term HAART. J Med Virol 2006; 78:1003-10. [PMID: 16789014 DOI: 10.1002/jmv.20655] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
HIV-1 p24 antigen (p24) measurement by signal amplification-boosted ELISA of heat-denatured plasma is being evaluated as an alternative to HIV-1 RNA quantitation in resource-poor settings. Some observations suggested that virion-associated p24 is suboptimally detected using Triton X-100-based virus dissociation buffer (kit buffer). A new reagent (SNCR buffer) containing both denaturing and non-denaturing detergents was therefore developed and evaluated. The SNCR buffer increased the measured p24 concentration about 1.5- to 3-fold in HIV-negative plasma reconstituted with purified HIV-1 particles, while not increasing the background. Among 127 samples of HIV-1-positive patients with moderate to high concentrations of HIV-1 RNA the increase was about threefold across the entire concentration range (P < 0.0001). Specificity before neutralization among prospectively tested clinical samples ruled HIV-negative was 828 of 845 (98.0%) for the SNCR buffer and 464 of 479 (96.9%) for kit buffer. Specificity after confirmatory neutralization of reactive samples or a follow-up test was 100% with either buffer. Surprisingly, the SNCR buffer revealed a p24 reactivity in 115 of 187 samples (61.5%) from adult patients exhibiting undetectable HIV-1 RNA below 5 copies/ml for a duration of 6-30 months under HAART (3.7% with kit buffer). The rate of p24 reactivity in these patients did not decrease with duration of HAART. In conclusion, the SNCR buffer improves the detection of particle-associated HIV-1 p24, thereby increasing the measured p24 concentration in samples with medium to high HIV-1 RNA. It also uncovers the presence of a p24 reactivity, whose identity remains to be determined, in a significant fraction of samples with undetectable HIV-1 RNA under long-term HAART.
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Affiliation(s)
- Jörg Schüpbach
- Swiss National Center for Retroviruses, University of Zurich, Zurich, Switzerland.
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20
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Brinkhof MWG, Böni J, Steiner F, Tomasik Z, Nadal D, Schüpbach J. Evaluation of p24-based antiretroviral treatment monitoring in pediatric HIV-1 infection: prediction of the CD4+ T-cell changes between consecutive visits. J Acquir Immune Defic Syndr 2006; 41:557-62. [PMID: 16652029 DOI: 10.1097/01.qai.0000209824.77784.2c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Worldwide, 700,000 infants are infected annually by HIV-1, most of them in resource-limited settings. Care for these children requires simple, inexpensive tests. We have evaluated HIV-1 p24 antigen for antiretroviral treatment (ART) monitoring in children. p24 by boosted enzyme-linked immunosorbent assay of heated plasma and HIV-1 RNA were measured prospectively in 24 HIV-1-infected children receiving ART. p24 and HIV-1 RNA concentrations and their changes between consecutive visits were related to the respective CD4+ changes. Age at study entry was 7.6 years; follow-up was 47.2 months, yielding 18 visits at an interval of 2.8 months (medians). There were 399 complete visit data sets and 375 interval data sets. Controlling for variation between individuals, there was a positive relationship between concentrations of HIV-1 RNA and p24 (P < 0.0001). While controlling for initial CD4+ count, age, sex, days since start of ART, and days between visits, the relative change in CD4+ count between 2 successive visits was negatively related to the corresponding relative change in HIV-1 RNA (P = 0.009), but not to the initial HIV-1 RNA concentration (P = 0.94). Similarly, we found a negative relationship with the relative change in p24 over the interval (P < 0.0001), whereas the initial p24 concentration showed a trend (P = 0.08). Statistical support for the p24 model and the HIV-1 RNA model was similar. p24 may be an accurate low-cost alternative to monitor ART in pediatric HIV-1 infection.
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Affiliation(s)
- Martin W G Brinkhof
- Institute for Social and Preventive Medicine, University of Berne, Berne, Switzerland
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21
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Patton JC, Sherman GG, Coovadia AH, Stevens WS, Meyers TM. Ultrasensitive human immunodeficiency virus type 1 p24 antigen assay modified for use on dried whole-blood spots as a reliable, affordable test for infant diagnosis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2006; 13:152-5. [PMID: 16426014 PMCID: PMC1356617 DOI: 10.1128/cvi.13.1.152-155.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ultrasensitive human immunodeficiency virus (HIV) p24 antigen assay was modified for use on pediatric dried whole-blood spots on Whatman no. 1 filter paper. The modified assay was found to be reliable and accurate, making it an affordable tool for pediatric HIV diagnosis in developing countries.
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Affiliation(s)
- Janet C Patton
- Wits Paediatric HIV Unit, Wits Health Consortium, University of the Witwatersrand, 7 York Rd., Parktown 2193, Johannesburg, South Africa.
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22
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Ondoa P, Dieye TN, Vereecken C, Camara M, Diallo AA, Fransen K, Litzroth A, Mboup S, Kestens L. Evaluation of HIV-1 p24 Antigenemia and Level of CD8+CD38+ T cells as Surrogate Markers of HIV-1 RNA Viral Load in HIV-1-Infected Patients in Dakar, Senegal. J Acquir Immune Defic Syndr 2006; 41:416-24. [PMID: 16652048 DOI: 10.1097/01.qai.0000209901.12750.d0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Alternative, affordable, and simple assays to monitor antiretroviral therapy (ART) in resource-poor settings are needed. We have evaluated and compared a heat-denatured (HD) HIV p24 amplified enzyme-linked immunosorbent assay from Perkin-Elmer and CD38CD8 T-cell levels, determined by flow cytometry, for their capacity to predict viral load (VL) in HIV-1-infected patients from Senegal. Median fluorescence intensity (MFI) of CD38 expression on memory (CD45RO) CD8 T cells correlated better with RNA VL than HD p24 antigenemia (R = 0.576, P < 0.0001 vs R = 0.548, P < 0.0001). MFI of CD38 expression on memory CD8 T cells could predict detectable RNA VL (VL = 2.6 log10) with a sensitivity of 87% and a specificity of 74%. A comparable sensitivity (89%) could be reached for HD p24 assay, but only to predict RNA VL of more than 5 logs, which might lead to unacceptable delays in clinical decision making. The clinical use of the HD p24 assay to monitor ART in Senegal would require more comparative data about the kinetics of p24 antigen and HIV RNA in peripheral blood as well as further evaluation regarding its sensitivity toward subtype A and CRF02. MFI of CD38 expression on memory CD8 T cells appeared to be a better alternative to monitor ART in HIV-infected patients from Senegal.
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Affiliation(s)
- Pascale Ondoa
- Institute of Tropical Medicine, Department of Microbiology, Antwerp-Belgium.
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23
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Jennings C, Fiscus SA, Crowe SM, Danilovic AD, Morack RJ, Scianna S, Cachafeiro A, Brambilla DJ, Schupbach J, Stevens W, Respess R, Varnier OE, Corrigan GE, Gronowitz JS, Ussery MA, Bremer JW. Comparison of two human immunodeficiency virus (HIV) RNA surrogate assays to the standard HIV RNA assay. J Clin Microbiol 2006; 43:5950-6. [PMID: 16333081 PMCID: PMC1317157 DOI: 10.1128/jcm.43.12.5950-5956.2005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus (HIV) RNA testing is the gold standard for monitoring antiretroviral therapy in HIV-infected patients. However, equipment and reagent costs preclude widespread use of the assay in resource-limited settings. The Perkin-Elmer Ultrasensitive p24 assay and the Cavidi Exavir Load assay both offer potentially simpler, less costly technologies for monitoring viral load. These assays were compared to the Roche Amplicor HIV-1 Monitor Test, v1.5, using panels of clinical samples (subtype B) from HIV-positive subjects and HIV-spiked samples (subtypes A, C, D, CRF_01AE, CRF_02AG, and F). The Ultrasensitive p24 assay detected 100% of the spiked samples with virus loads of >250,000 copies/ml and 61% of the clinical samples with virus loads of 219 to 288,850 copies/ml. Detection rates were improved substantially if an external lysis buffer was added to the procedure. The Cavidi assay detected 54 to 100% of spiked samples with virus loads >10,000 copies/ml and 68% of the clinical samples. These detection rates were also greatly improved with a newly implemented version of this kit. Coefficients of variation demonstrate good reproducibility for each of these kits. The results from the Cavidi v1.0, Cavidi v2.0, and Perkin-Elmer, and the Perkin-Elmer Plus external buffers all correlated well with the results from the Roche Monitor Test (r = 0.83 to 0.96, r = 0.84 to 0.99, r = 0.58 to 0.67, and r = 0.59 to 0.95, respectively). Thus, the use of these two assays for monitoring patients, together with less-frequent confirmation testing, offers a feasible alternative to frequent HIV RNA testing in resource-limited settings.
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Affiliation(s)
- Cheryl Jennings
- Rush Medical College, Department of Immunology/Microbiology, 1653 W. Congress Parkway, Chicago, IL 60612, USA.
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24
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Schüpbach J, Günthard H, Joos B, Fischer M, Böni J, Tomasik Z, Yerly S, Perrin L, Battegay M, Furrer H, Vernazza P, Bernasconi E, Hirschel B. HIV-1 p24 may persist during long-term highly active antiretroviral therapy, increases little during short treatment breaks, and its rebound after treatment stop correlates with CD4(+) T cell loss. J Acquir Immune Defic Syndr 2005; 40:250-6. [PMID: 16249697 DOI: 10.1097/01.qai.0000181281.75670.56] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The dynamics of HIV-1 RNA during structured treatment interruptions (STIs) are well established, but little is known about viral proteins like p24. We studied 65 participants of an STI trial. Before the trial, continuous highly active antiretroviral therapy (HAART) had suppressed their viral load to <50 copies/mL during 6 months. They then interrupted HAART during weeks 1 through 2, 11 through 12, 21 through 22, 31 through 32, and 41 through 52. The p24 was measured by boosted enzyme-linked immunosorbent assay of plasma pretreated by efficient virus disruption and heat denaturation. At time point 0, p24 was measurable in 22 patients (34%), who had maintained a viral load <50 copies/mL for 25.4 months (median, range: 6.2-38.9 months) under HAART. Viral rebounds during 2-week STIs led to a mean p24 increase of only 0.08 to 0.19 log10 (ie, 20%-60%). Pre-HAART viral load and p24 at time 0 independently predicted p24 rebounds during the 4 2-week STIs. The p24 at time 0 and HIV-1 RNA rebound during weeks 41 through 52 independently determined the concomitant p24 rebound. An increase of p24 but not viral load during the first 8 weeks of the long STI correlated significantly with concomitant CD4(+) T cell loss. Persisting p24 despite successful HAART may reflect virus replication in reservoirs not represented by plasma viral load and has implications for the concept of therapeutic vaccination.
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Affiliation(s)
- Jörg Schüpbach
- Swiss National Center for Retroviruses, University of Zurich, Zurich, Switzerland.
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25
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Ryan G, Grimes T, Brankin B, Mabruk MJEMF, Hosie MJ, Jarrett O, Callanan JJ. Neuropathology associated with feline immunodeficiency virus infection highlights prominent lymphocyte trafficking through both the blood-brain and blood-choroid plexus barriers. J Neurovirol 2005; 11:337-45. [PMID: 16162477 DOI: 10.1080/13550280500186445] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Feline immunodeficiency virus (FIV) infection in the cat is a well-evaluated model of human immunodeficiency virus (HIV)-1 infection in man with both viruses associated with significant neuropathology. Although studies in both HIV and FIV infections have shown that virus enters the brain in the acute stages of disease, little is known of the mechanisms of viral entry. The dissection of this stage is fundamental to the development of therapies that may prevent or modulate central nervous system (CNS) infection. The present study was designed to characterize the early sequential neuropathological changes following infection with FIV(GL8), a strain known to enter the CNS in acute infection. Cats were infected either by the intraperitoneal (n = 13) or intravenous (n = 12) route with 2000 cat infectious units of virus. Histopathological assessments following intraperitoneal infections were at 4 (n = 2), 5 (n = 1), 8 (n = 3), 10 (n = 1), 16 (n = 1), 32 (n = 2), 52 (n = 2), and 104 (n = 1) weeks post infection whereas animals infected intravenously were examined (n = 3) at 1, 4, 10, and 23 weeks post infection. The most significant lesions following both routes of infection were lymphocyte-rich perivascular infiltrates within cerebral and cerebellar meninges, in choroid plexus and spinal cord dura mater and within epineurium of the sciatic nerve. In addition, following intravenous infection perivascular infiltrations were noted in parenchymal blood vessels primarily of cerebral white matter. Infiltrates were composed of CD79+ B cells and CD3+ T cells. The latter population contained a mixture of CD4+ and CD8+ cells. The severity of lesions increased in intensity in the 8-to 16-week period following infection and then began to wane. The evaluation of this large group of cats at multiple time points revealed pathology comparable with that of early stage HIV-1-associated encephalitis. Moreover, in contrast to previous FIV neuropathology studies, transient meningeal, choroid plexus, and parenchymal vascular pathology were consistent significant findings suggesting that, as in HIV-1 infection, blood-brain barrier and choroid plexus brain barrier integrity are both compromised in early infection.
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Affiliation(s)
- Gavin Ryan
- Department of Veterinary Pathology, University College Dublin, Dublin, Ireland
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26
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Li CC, Seidel KD, Coombs RW, Frenkel LM. Detection and quantification of human immunodeficiency virus type 1 p24 antigen in dried whole blood and plasma on filter paper stored under various conditions. J Clin Microbiol 2005; 43:3901-5. [PMID: 16081929 PMCID: PMC1233947 DOI: 10.1128/jcm.43.8.3901-3905.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The quantification of human immunodeficiency virus type 1 (HIV-1) by an assay measuring heat-dissociated (HD) p24 antigen (Ag) in specimens of whole blood and plasma stored on filter paper, and of plasma stored in tubes, was compared to HIV-1 RNA plasma levels determined by real-time reverse transcription (RT)-PCR. The stability of p24 Ag on filter paper under conditions simulating specimen transport was also evaluated. The HD p24 Ag in both plasma and whole-blood specimens stored on filter paper correlated with plasma HIV-1 RNA levels (Spearman rank rho = 0.74 [P < 0.0001] and rho = 0.56 [P = 0.0001], respectively). The sensitivity of the HD p24 Ag assay was similar when plasma and whole blood on filter paper were contrasted to the real-time RT-PCR assay (80% versus 82.5% and 78.6% versus 83.3%, respectively). However, while the specificity of the HD p24 Ag assay of plasma on filter paper was 100%, the specificity was diminished in whole-blood specimens. The storage of specimens on filter paper for 2 weeks at 37 degrees C, 24 degrees C, or 0 degrees C did not alter the detection or quantification of HD p24 Ag. These results suggest that transport and storage of plasma on filter paper and quantification of HD p24 Ag may be a reliable method for HIV-1 load monitoring.
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Affiliation(s)
- Chung-Chen Li
- Departments of Pediatrics, Laboratory Medicine, Medicine, University of Washington, Department of Biostatistics, Children's Hospital and Regional Medical Center, Seattle, Washington, Departments of Pediatrics, Chang-Gang Children's Hospital, Kaohsiung, Taiwan
| | - Kristy D. Seidel
- Departments of Pediatrics, Laboratory Medicine, Medicine, University of Washington, Department of Biostatistics, Children's Hospital and Regional Medical Center, Seattle, Washington, Departments of Pediatrics, Chang-Gang Children's Hospital, Kaohsiung, Taiwan
| | - Robert W. Coombs
- Departments of Pediatrics, Laboratory Medicine, Medicine, University of Washington, Department of Biostatistics, Children's Hospital and Regional Medical Center, Seattle, Washington, Departments of Pediatrics, Chang-Gang Children's Hospital, Kaohsiung, Taiwan
| | - Lisa M. Frenkel
- Departments of Pediatrics, Laboratory Medicine, Medicine, University of Washington, Department of Biostatistics, Children's Hospital and Regional Medical Center, Seattle, Washington, Departments of Pediatrics, Chang-Gang Children's Hospital, Kaohsiung, Taiwan
- Corresponding author. Mailing address: 307 Westlake Avenue North, Suite 300, Room 330, Seattle, WA 98105. Phone: (206) 987-5140. Fax: (206) 987-7311. E-mail:
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27
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Stevens G, Rekhviashvili N, Scott LE, Gonin R, Stevens W. Evaluation of two commercially available, inexpensive alternative assays used for assessing viral load in a cohort of human immunodeficiency virus type 1 subtype C-infected patients from South Africa. J Clin Microbiol 2005; 43:857-61. [PMID: 15695692 PMCID: PMC548057 DOI: 10.1128/jcm.43.2.857-861.2005] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although human immunodeficiency virus type 1 (HIV-1) RNA is the acknowledged "gold standard" marker for monitoring disease activity in patients receiving highly active antiretroviral therapy (HAART), it remains unaffordable in resource-constrained settings. The present study investigated two commercially available kits for the detection of HIV-1 viral load markers as more affordable alternatives to HIV-1 RNA quantitation. The greatly improved heat-denatured, signal-boosted HiSens HIV-1 p24 Ag Ultra kit (Perkin-Elmer) and the ExaVir Load Quantitative HIV-RT kit (Cavidi Tech AB) were compared with the Amplicor HIV-1 Monitor (version 1.5) assay (Roche Molecular Systems Inc.). A total of 117 samples containing HIV-1 subtype C were analyzed by all three methodologies. Eighty-nine of these samples represented serial measurements from 20 patients receiving HAART. The remaining samples analyzed were from a group of treatment-naive patients. The association between the p24 antigen assay and the RNA assay was fairly strong (R(2) = 0.686). The association between the reverse transcriptase (RT) quantitation assay and the RNA assay was strong (R(2) = 0.810). Both alternative assays seemed most useful for the serial monitoring of patients receiving HAART (n = 89 plasma samples from 20 patients), as all assays showed a statistically significant downward trend over time, with the trend being either linear or curvilinear. In addition, all three assays showed negative correlations with the CD4 count (CD4 count versus RNA load, r = -0.336 and P = 0.001; CD4 count versus p24 antigen level, r = -0.541 and P < 0.0001; CD4 count versus RT level, r = -0.358 and P = 0.0006). Still of major concern are both the lack of sensitivity and the wide degrees of variability of both assays. However, both assays provide a less expensive alternative to the Roche viral load assay and demonstrate the same trends during treatment.
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Affiliation(s)
- G Stevens
- Department of Molecular Medicine and Haematology, School of Pathology, University of the Witwatersrand Medical School, Faculty of Health Science and the NHLS, Johannesburg 2193, South Africa.
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28
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Respess RA, Cachafeiro A, Withum D, Fiscus SA, Newman D, Branson B, Varnier OE, Lewis K, Dondero TJ. Evaluation of an ultrasensitive p24 antigen assay as a potential alternative to human immunodeficiency virus type 1 RNA viral load assay in resource-limited settings. J Clin Microbiol 2005; 43:506-8. [PMID: 15635029 PMCID: PMC540096 DOI: 10.1128/jcm.43.1.506-508.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An inexpensive enzyme-linked immunosorbent assay method for human immunodeficiency virus type 1 quantitation, ultrasensitive p24 antigen assay (Up24), was compared with RNA viral load assay (VL). Up24 had 100% sensitivity of detection at a viral load of >/=30,000, with sensitivity of 46.4% at a viral load of <30,000 (232 specimens from 65 seropositive subjects). The assay was highly reproducible, with excellent correlation between duplicates and among three laboratories.
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Affiliation(s)
- Richard A Respess
- Global AIDS Program, National Center for HIV, STD and TB Prevention, Centers for Disease Control and Prevention, 1600 Clifton Rd., Mail Stop A-12, Atlanta, GA 30333, USA.
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29
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Prado JG, Shintani A, Bofill M, Clotet B, Ruiz L, Martinez-Picado J. Lack of longitudinal intrapatient correlation between p24 antigenemia and levels of human immunodeficiency virus (HIV) type 1 RNA in patients with chronic hiv infection during structured treatment interruptions. J Clin Microbiol 2004; 42:1620-5. [PMID: 15071015 PMCID: PMC387543 DOI: 10.1128/jcm.42.4.1620-1625.2004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Structured treatment interruptions (STIs) have been proposed as a potential treatment strategy during human immunodeficiency virus type 1 (HIV-1) antiretroviral therapy. This still-experimental intervention requires a close monitoring of patients' plasma viremia and CD4(+)-T-cell counts during the treatment interruption phase. By using signal amplification of a heat-dissociated p24 antigen (p24Ag) assay, we compared p24Ag levels with levels of HIV RNA in plasma. One hundred seventy-four plasma samples were obtained from 51 chronically HIV-infected patients: 117 from patients who underwent STIs and 57 from patients who did not. Partial immune complex dissociation and clearance of those complexes by the erythrocytes were also investigated. A significant association between the two assays was observed (beta = 0.23, 95% confidence interval = 0.18, 0.28; P < 0.0001), but the association was smaller in the subset of samples from patients undergoing STIs. Moreover, discordant results and lack of longitudinal intrapatient correlation between levels of p24Ag and HIV-1 RNA were higher in this group. Incomplete immune complex dissociation and binding of those complexes to erythrocytes could be contributing factors involved in the diminished detection of p24Ag. Therefore, signal amplification of a heat-dissociated p24Ag had a positive association with current HIV RNA assays in a population-based analysis. However, it might not be sensitive enough to monitor longitudinal intrapatient viremia during STIs in patients with high CD4(+)-T-cell counts potentially due to the production of high-affinity anti-p24 antibodies and clearance of immune complexes by erythrocytes.
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Affiliation(s)
- Julia G Prado
- IrsiCaixa Foundation, Hospital Germans Trias i Pujol, Universitat Autonoma de Barcelona, Badalona, Spain
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30
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Renne R, Dittmer D, Kedes D, Schmidt K, Desrosiers RC, Luciw PA, Ganem D. Experimental transmission of Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) to SIV-positive and SIV-negative rhesus macaques. J Med Primatol 2004; 33:1-9. [PMID: 15061726 DOI: 10.1046/j.1600-0684.2003.00043.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is a gamma-herpesvirus associated with Kaposi's sarcoma (KS) and two lymphoproliferative diseases, primary effusion lymphoma (PEL) and multicentric Castleman's disease. Studies on the biology and pathogenesis of KSHV have been limited by lack of efficient cell culture systems and lack of a suitable animal model for KS. Here we report on the experimental inoculation of SIV-positive and SIV-negative rhesus macaques with KSHV-infected PEL cells or KSHV preparations derived from PEL cells. Low levels of viral DNA could be detected in cultivated peripheral blood mononuclear cell of all animals, as well as in the bone marrow of one monkey that died from SAIDS. However, we were not able to detect KSHV-specific antibodies or transcripts, nor did we observe any symptoms clearly related to KSHV infection (e.g. KS or lympho-proliferative disease). Hence, although KSHV replicates in rhesus macaques at very low levels, this non-human primate host is unlikely to provide a useful animal model for disease.
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Affiliation(s)
- R Renne
- Departments of Medicine and Microbiology, Division of Hematology and Oncology, Case Western Reserve University, 10900 Euclid Avenue, BRB3 West, Cleveland, OH 44106-4937, USA.
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31
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Bonard D, Rouet F, Toni TA, Minga A, Huet C, Ekouévi DK, Dabis F, Salamon R, Rouzioux C. Field evaluation of an improved assay using a heat-dissociated p24 antigen for adults mainly infected with HIV-1 CRF02_AG strains in Côte d'Ivoire, West Africa. J Acquir Immune Defic Syndr 2003; 34:267-73. [PMID: 14600570 DOI: 10.1097/00126334-200311010-00002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The aim of this study was to evaluate the heat-dissociated p24 antigen (HD p24 Ag) assay as an alternative low-cost tool for diagnosis of HIV-1 infection and quantitation of HIV-1 RNA levels in African adults mainly infected with HIV-1 CRF02_AG strains. One hundred seventeen plasma specimens were obtained from HIV-1-seropositive subjects enrolled in the ANRS 1220 PRIMO-CI cohort (Abidjan, Côte d'Ivoire, West Africa). Results of the HD p24 Ag assay were comparable with those of HIV-1 RNA levels quantified in the same antibody-positive plasma samples by the Amplicor HIV-1 Monitor assay (1.5 version; Roche Diagnostics, Indianapolis, IN): sensitivity, 95.7% versus 96.6%, respectively; specificity (evaluated with samples from 75 seronegative subjects), 94.7% versus 100%, respectively. HD p24 Ag and HIV-1 RNA assays were weakly correlated (Spearman coefficient correlation, r = 0.33; P < 0.001) except for HIV-1 RNA levels of >/=5 log10 copies/mL (r = 0.62; P < 0.001). Quantitation of HD p24 antigenemia in 76 plasma specimens from 14 patients treated with highly active antiretroviral therapy demonstrated weaker changes during treatment than those observed with the HIV-1 RNA assay. Follow-up of infected patients using both markers showed different results. The reliability of the HD p24 Ag assay is questionable for clinical and biologic management as a surrogate tool for measurement of HIV-1 RNA levels in Africa.
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Affiliation(s)
- D Bonard
- Centre de Diagnostic et de Recherches sur le SIDA, CHU de Treichville, BP V3 Abidjan, Côte d'Ivoire, West Africa.
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32
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Schüpbach J. Viral RNA and p24 Antigen as Markers of HIV Disease and Antiretroviral Treatment Success. Int Arch Allergy Immunol 2003; 132:196-209. [PMID: 14646380 DOI: 10.1159/000074552] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
HIV-1 RNA has become the standard for monitoring antiretroviral therapies. Dogma predicts, however, that a viral protein like p24 should be at least as good a marker of HIV disease activity, provided that it is measured with sufficient sensitivity and accuracy. Simple modifications including use of a more efficient virus lysis buffer, heat-mediated destruction of antibodies interfering with antigen detection, and tyramide signal amplification for increased sensitivity have highly improved the HIV-1 p24 antigen assay. The p24 antigen assay is inferior to RT-PCR in detecting viral particles, but the presence of extraviral p24 antigen in most samples makes largely up for this. p24 antigen testing is similarly sensitive and specific in diagnosing pediatric HIV infection, in predicting CD4+ T cell decline and clinical progression at early and late stage of infection, and suitable for antiretroviral treatment monitoring in both adults and children. Notably, p24 antigen was measurable even in patients with stably suppressed viremia, and its concentrations were correlated negatively with the concentrations of CD4+ T cells and positively with the concentrations of activated CD8+ T cell subsets. p24 antigen is an excellent marker of HIV expression and disease activity and can be used in the same fields of application as HIV RNA is used. The test is validated for subtype B, but requires further studies for non-B subtypes.
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Affiliation(s)
- Jörg Schüpbach
- Swiss National Center for Retroviruses, University of Zürich, Zürich, Switzerland.
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33
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Ryan G, Klein D, Knapp E, Hosie MJ, Grimes T, Mabruk MJEMF, Jarrett O, Callanan JJ. Dynamics of viral and proviral loads of feline immunodeficiency virus within the feline central nervous system during the acute phase following intravenous infection. J Virol 2003; 77:7477-85. [PMID: 12805447 PMCID: PMC164807 DOI: 10.1128/jvi.77.13.7477-7485.2003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2002] [Accepted: 04/12/2003] [Indexed: 11/20/2022] Open
Abstract
Animal models of human immunodeficiency virus 1, such as feline immunodeficiency virus (FIV), provide the opportunities to dissect the mechanisms of early interactions of the virus with the central nervous system (CNS). The aims of the present study were to evaluate viral loads within CNS, cerebrospinal fluid (CSF), ocular fluid, and the plasma of cats in the first 23 weeks after intravenous inoculation with FIV(GL8). Proviral loads were also determined within peripheral blood mononuclear cells (PBMCs) and brain tissue. In this acute phase of infection, virus entered the brain in the majority of animals. Virus distribution was initially in a random fashion, with more diffuse brain involvement as infection progressed. Virus in the CSF was predictive of brain parenchymal infection. While the peak of virus production in blood coincided with proliferation within brain, more sustained production appeared to continue in brain tissue. In contrast, proviral loads in the brain decreased to undetectable levels in the presence of a strengthening PBMC load. A final observation in this study was that there was no direct correlation between viral loads in regions of brain or ocular tissue and the presence of histopathology.
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Affiliation(s)
- G Ryan
- Department of Veterinary Pathology, Faculty of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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34
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Schüpbach J, Böni J, Bisset LR, Tomasik Z, Fischer M, Günthard HF, Ledergerber B, Opravil M. HIV-1 p24 antigen is a significant inverse correlate of CD4 T-cell change in patients with suppressed viremia under long-term antiretroviral therapy. J Acquir Immune Defic Syndr 2003; 33:292-9. [PMID: 12843739 DOI: 10.1097/00126334-200307010-00002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
An HIV-1 p24 antigen test involving signal amplification-boosted ELISA of heat-denatured plasma was evaluated prospectively in 55 patients whose viral RNA in plasma had previously been suppressed for at least 6 months under antiretroviral combination therapy. During a median follow-up of 504 days, CD4 counts increased by a median of 62 cells per year. By univariate and multivariate linear regression analysis, the level of p24 antigen as expressed by the absorbance/cutoff ratio was a significant inverse correlate of both the CD4 count in a sample (p =.013) and its annual change in a patient (p <.0001). The p24 antigen retained significance even among 48 individuals whose HIV-1 RNA, apart from occasional blips, remained below 400 copies/mL. Batch-wise retesting of 70 samples from 5 such patients with a further improved procedure showed measurable p24 antigen in all but 1 sample and an inverse correlation with both the CD4 count (p =.0331) and percentage (p <.0001), thus confirming the prospectively generated data. Comparison of p24 antigen and HIV-1 RNA concentrations indicate that the p24 antigen detected in these samples is not associated with viral RNA-containing particles and may originate from other compartments of virus expression.
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Affiliation(s)
- Jörg Schüpbach
- Swiss National Center for Retroviruses, University of Zurich, Zurich, Switzerland.
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35
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Liu F, Guttikonda S, Suresh MR. Bispecific monoclonal antibodies against a viral and an enzyme: utilities in ultrasensitive virus ELISA and phage display technology. J Immunol Methods 2003; 274:115-27. [PMID: 12609538 DOI: 10.1016/s0022-1759(02)00511-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A quadroma (hybrid-hybridoma) secreting bispecific antibodies with one paratope specific for M13 bacteriophage coat protein and another paratope specific for alkaline phosphatase (AP) was developed by electro-fusion of the two parental hybridomas and selected by a fluorescence activated cell sorter (FACS). The anti-phage M13/anti-AP bsMAbs were purified from anti-phage M13 monospecific MAb by a novel affinity method using Mimetic Blue A6XL as immune complexes with AP. The purified bsMAbs with potentially every molecule uniformly bound with AP generated an immuno-probe with the theoretical highest specificity. An ultrasensitive sandwich ELISA for detecting viruses was developed by using this bsMAb coupled with an amplified ELISA procedure. The sensitivity of the assay was increased 1000 times compared with conventional ELISA to achieve detection of 100 phage particles which is approximately 2.3 fg of phage coat protein. This type of bsMAb probe and ELISA format can be used to design new body fluid assays for viral load of HIV, hepatitis and other human pathogens as rapid and inexpensive alternatives to the PCR based method. This unique bispecific probe also allowed rapid and sensitive detection of bound M13/fd phage clones while panning for specific phages displaying peptide mimics against an antigen from a phage display peptide library. Furthermore, we demonstrate the principle virus purification using bsMAb as affinity ligand with a mild phosphate buffer elution. The results indicate that bsMAb could be used to develop affinity chromatography for purifying highly contagious and pathogenic viruses avoiding procedures employing prolonged high-speed centrifugation.
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Affiliation(s)
- Fei Liu
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, #3118, DP Building, T6G 2N8, Edmonton, AB, Canada
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36
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Sutthent R, Gaudart N, Chokpaibulkit K, Tanliang N, Kanoksinsombath C, Chaisilwatana P. p24 Antigen detection assay modified with a booster step for diagnosis and monitoring of human immunodeficiency virus type 1 infection. J Clin Microbiol 2003; 41:1016-22. [PMID: 12624024 PMCID: PMC150255 DOI: 10.1128/jcm.41.3.1016-1022.2003] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We modified a p24 antigen enzyme-linked immunosorbent assay as a method for diagnosis and monitoring of human immunodeficiency virus type 1 (HIV-1) subtype E infection. This modified assay is based on the use of preheated immune complex dissociation combined with a booster step using a regular Vironostika HIV-1 p24 antigen assay (bioMerieux) to decrease the lower limit of p24 antigen detection from 10 pg/ml (lower limit achievable when using a regular p24 antigen assay) to 0.5 pg/ml (100 virions/ml) by the new method. The correlation between the values obtained by the HIV-1 RNA (Amplicor HIV-1 Monitor) assay and the p24 antigen assay modified with a booster step antigen assay in 160 frozen plasma samples with known viral load and 80 blind fresh plasma samples by Spearman rank were 0.671 (R(2) = 0.450; P < 0.01) and 0.782 (R(2) = 0.612; P < 0.01). During antiretroviral treatment, the change of p24 antigen level at >/=0.5 log correlated well with the level of HIV-1 in plasma. In order to improve the early diagnosis of HIV-1 infection in 121 infants born to HIV-1-infected mothers, a heat-denatured plasma p24 antigen assay modified with a booster step was compared with DNA-PCR and HIV RNA (nucleic acid sequence-based amplification) assays. The sensitivity of the antigen test modified with a booster step was similar to that of the HIV-1 RNA (NASBA QL) assay and better than that of the DNA-PCR assay (100 versus 61.90%) for subjects 1 to 2 months old. The overall results from this study might renew interest in p24 antigen detection as an easily affordable alternative method for diagnosis of HIV-1 infection and monitoring of disease progression in developing countries.
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Affiliation(s)
- Ruengpung Sutthent
- Departments of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
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37
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Odawara F, Abe H, Kohno T, Nagai-Fujii Y, Arai K, Imamura S, Misaki H, Azuma H, Ikebuchi K, Ikeda H, Mohan S, Sano K. A highly sensitive chemiluminescent reverse transcriptase assay for human immunodeficiency virus. J Virol Methods 2002; 106:115-24. [PMID: 12367736 DOI: 10.1016/s0166-0934(02)00142-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A simple and highly sensitive reverse transcriptase (RT) assay was developed by combining a previously reported non-radioisotopic RT assay with the use of a template-primer-immobilized microplate, an enzyme capture protocol, product digestion and a chemiluminescent substrate. The assay was able to detect directly the RT activity in serum samples, plasma and cell culture medium without the need for concentration and extraction of the enzyme. The assay was able to detect RT activity equivalent to 100 virions/ml of HIV-1. These results suggest that this highly sensitive chemiluminescent RT assay can be used not only for virological investigation but also for routine screening of biopharmaceuticals.
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Affiliation(s)
- Fumitomo Odawara
- Fine Chemicals and Diagnostic Division, Asahi Kasei Corporation, 632-1 Mifuku, Ohito-cho, Tagata-gun, Shizuoka 410-2321, Japan.
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38
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Pascual A, Cachafeiro A, Funk ML, Fiscus SA. Comparison of an assay using signal amplification of the heat-dissociated p24 antigen with the Roche Monitor human immunodeficiency virus RNA assay. J Clin Microbiol 2002; 40:2472-5. [PMID: 12089264 PMCID: PMC120606 DOI: 10.1128/jcm.40.7.2472-2475.2002] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We compared an assay using signal amplification of a heat-dissociated p24 antigen (HDAg) with the Roche Monitor human immunodeficiency virus (HIV) RNA assay. The two assays gave comparable results when 130 specimens from 130 patients were tested (r = 0.60, P < 0.0001). The HDAg assay was almost as sensitive (85%) as the Roche HIV RNA kit (95%), just as specific (25 negative results from 25 HIV seronegative volunteers [100%]), less variable (mean log standard deviation of 0.07 compared to 0.11 when eight specimens were tested three or four times), and less expensive (reagent and labor costs, $8 versus $75). The assay appeared to be useful for monitoring established patients (n = 17) and identifying seroconverters (n = 4). HIV subtypes A to F were all recognized. This assay should be useful for monitoring patients in resource-poor countries and for monitoring vaccine recipients.
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Affiliation(s)
- Alvaro Pascual
- Department of Microbiology, Universidad de Sevilla, Seville, Spain
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39
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Hofmann-Lehmann R, Williams AL, Swenerton RK, Li PL, Rasmussen RA, Chenine AL, McClure HM, Ruprecht RM. Quantitation of simian cytokine and beta-chemokine mRNAs, using real-time reverse transcriptase-polymerase chain reaction: variations in expression during chronic primate lentivirus infection. AIDS Res Hum Retroviruses 2002; 18:627-39. [PMID: 12079558 DOI: 10.1089/088922202760019329] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cytokines and beta-chemokines are important mediators of the immune system and are expressed in many infectious diseases. To study cytokine and beta-chemokine profiles during pathogenesis of lentiviral infection and progression to AIDS in rhesus macaques, we established new quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assays based on TaqMan chemistry. Using synthetic RNA standards, we quantified mRNAs of IL-2, IL-4, IL-6, IL-10, IL-12 p40, interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), RANTES, macrophage inflammatory protein 1 alpha (MIP-1 alpha), and MIP-1 beta in unstimulated peripheral blood mononuclear cells (PBMCs) and lymph nodes from macaques chronically infected with SIV or SHIV. Viremic monkeys with decreased CD4(+) T cell counts (<500 cells/microl) had significantly higher IL-10 mRNA expression than uninfected controls, which parallels the findings in HIV-1-infected humans. In addition, MIP-1 alpha, MIP-1 beta, and RANTES mRNA expression increased in viremic monkeys with decreased CD4(+) T cell counts; gene expression was inversely correlated with CD4(+) T cell counts, but not viral load. The newly established quantitative real-time RT-PCR assays will allow the determination of cytokine and beta-chemokine patterns in rhesus macaques in studies of microbial pathogenesis or vaccine development.
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Affiliation(s)
- Regina Hofmann-Lehmann
- Dana-Farber Cancer Institute and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA
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40
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Woodbury RL, Varnum SM, Zangar RC. Elevated HGF levels in sera from breast cancer patients detected using a protein microarray ELISA. J Proteome Res 2002; 1:233-7. [PMID: 12645900 DOI: 10.1021/pr025506q] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We developed an ELISA in high-density microarray format to detect hepatocyte growth factor (HGF) in human serum. The microassay can detect HGF at sub-pg/mL concentrations in sample volumes of 100 microL or less. The microassay is also quantitative and was used to detect elevated HGF levels in sera from recurrent breast cancer patients. The microarray format provides the potential for high-throughput quantitation of multiple biomarkers in parallel, as demonstrated with a multiplex analysis of five biomarker proteins.
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Affiliation(s)
- Ronald L Woodbury
- Battelle, Pacific Northwest National Laboratory, Molecular Biosciences Department, P7-56, P.O. Box 999, Richland, Washington 99352, USA
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41
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Keppler OT, Welte FJ, Ngo TA, Chin PS, Patton KS, Tsou CL, Abbey NW, Sharkey ME, Grant RM, You Y, Scarborough JD, Ellmeier W, Littman DR, Stevenson M, Charo IF, Herndier BG, Speck RF, Goldsmith MA. Progress toward a human CD4/CCR5 transgenic rat model for de novo infection by human immunodeficiency virus type 1. J Exp Med 2002; 195:719-36. [PMID: 11901198 PMCID: PMC2193739 DOI: 10.1084/jem.20011549] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The development of a permissive small animal model for the study of human immunodeficiency virus type (HIV)-1 pathogenesis and the testing of antiviral strategies has been hampered by the inability of HIV-1 to infect primary rodent cells productively. In this study, we explored transgenic rats expressing the HIV-1 receptor complex as a susceptible host. Rats transgenic for human CD4 (hCD4) and the human chemokine receptor CCR5 (hCCR5) were generated that express the transgenes in CD4(+) T lymphocytes, macrophages, and microglia. In ex vivo cultures, CD4(+) T lymphocytes, macrophages, and microglia from hCD4/hCCR5 transgenic rats were highly susceptible to infection by HIV-1 R5 viruses leading to expression of abundant levels of early HIV-1 gene products comparable to those found in human reference cultures. Primary rat macrophages and microglia, but not lymphocytes, from double-transgenic rats could be productively infected by various recombinant and primary R5 strains of HIV-1. Moreover, after systemic challenge with HIV-1, lymphatic organs from hCD4/hCCR5 transgenic rats contained episomal 2-long terminal repeat (LTR) circles, integrated provirus, and early viral gene products, demonstrating susceptibility to HIV-1 in vivo. Transgenic rats also displayed a low-level plasma viremia early in infection. Thus, transgenic rats expressing the appropriate human receptor complex are promising candidates for a small animal model of HIV-1 infection.
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Affiliation(s)
- Oliver T Keppler
- Gladstone Institute of Virology and Immunology, School of Medicine, University of California at San Francisco, San Francisco, CA 94141, USA
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42
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Chakrabarti LA, Ivanovic T, Cheng-Mayer C. Properties of the surface envelope glycoprotein associated with virulence of simian-human immunodeficiency virus SHIV(SF33A) molecular clones. J Virol 2002; 76:1588-99. [PMID: 11799153 PMCID: PMC135897 DOI: 10.1128/jvi.76.4.1588-1599.2002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In vivo adaptation of simian-human immunodeficiency virus (SHIV) clone SHIV(SF33) resulted in the emergence of pathogenic isolate SHIV(SF33A), which caused a rapid and severe CD4(+) T-cell depletion when inoculated into rhesus macaques. Two molecular clones generated by inserting the env V1-to-V5 region amplified from SHIV(SF33A)-infected animals into the parental SHIV(SF33) genome retained a pathogenic phenotype. The gp120 envelope glycoproteins of pathogenic clones SHIV(SF33A2) and SHIV(SF33A5) conferred a threefold increase in viral entry and fusogenicity compared to the parental glycoprotein. Changes in gp120 were also responsible for a higher replication capacity and cytopathicity in primary CD4(+) T-cell cultures. Last, gp120 carried the determinants of SHIV(SF33A) neutralization resistance. Thus, changes in SHIV(SF33A) gp120 produced a set of properties that could account for the pathogenic phenotype observed in vivo. Measurement of antibody binding to SHIV(SF33A) viral particles revealed an increased exposure of the CD4-induced epitope recognized by the 17b monoclonal antibody in a region that was shown to contribute to coreceptor binding. Exposure of this epitope occurred in the absence of CD4 binding, suggesting that the envelope glycoprotein of pathogenic SHIV(SF33A) clones folded in a conformation that was primed for interaction with CXCR4 or for the subsequent step of fusion.
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Affiliation(s)
- Lisa A Chakrabarti
- Aaron Diamond AIDS Research Center, The Rockefeller University, New York, New York 10016, USA
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43
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Schüpbach J, Böni J, Flepp M, Tomasik Z, Joller H, Opravil M. Antiretroviral treatment monitoring with an improved HIV-1 p24 antigen test: an inexpensive alternative to tests for viral RNA. J Med Virol 2001; 65:225-32. [PMID: 11536227 DOI: 10.1002/jmv.2024] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Monitoring of viral RNA has become indispensable for the management of HIV-1 infection, but is expensive. This study investigated whether a highly improved test for p24 antigen could serve as an alternative. Thirty-four patients enrolled during 1997 into two treatment studies were tested prospectively for viral RNA by the Roche HIV-1 Monitor and for p24 antigen using signal-amplification-boosted ELISA of heat-denatured plasma. P24 antigen was detectable in 75.8% of 178 samples and HIV RNA in 73.9% of 138 samples. The half-life of p24 antigen in the first phase of effective treatment was 1.6 +/-.4 days (RNA, 1.7 +/-.8). An apparent second, slower decay phase had a half-life of 42 +/- 16 days. Treatment failure occurred in 14 patients. Secondary treatment failures with RNA rebounds from undetectable levels to < or = 10(3) copies/ml in two patients with an undetectable viral load and 10(3) HIV RNA copies/ml, respectively, at baseline were not detected by p24 antigen but carried a low risk for secondary resistance mutations. The other 12 failures were on average detected 29 days earlier by p24 antigen than by RNA (P =.0204), owing to slightly more frequent testing for p24 than for RNA (2.7 vs. 2.4 tests). Average costs for p24 antigen testing up to a failure were only 20.5% of those for RNA (P <.0001). These results indicate that heat-denatured, amplification-boosted p24 antigen measurement can be used as a simple and inexpensive alternative to HIV RNA testing for monitoring treatment.
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Affiliation(s)
- J Schüpbach
- Swiss National Center for Retroviruses, University of Zürich, Zürich, Switzerland.
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44
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Saloojee H, Violari A. Regular review: HIV infection in children. BMJ (CLINICAL RESEARCH ED.) 2001; 323:670-4. [PMID: 11566832 PMCID: PMC1121236 DOI: 10.1136/bmj.323.7314.670] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- H Saloojee
- Division of Community Paediatrics, Department of Paediatrics and Child Health, University of the Witwatersrand, PO Wits, 2050, Johannesburg, South Africa.
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45
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Marcelino JM, Novo C, Pereira JM, Picotez F, Clemente A, Taveira N. Production and characterization of a mouse monoclonal antibody against the Gag p26 protein of human immunodeficiency virus type 2: identification of a new antigenic epitope. AIDS Res Hum Retroviruses 2001; 17:1279-83. [PMID: 11559428 DOI: 10.1089/088922201750461348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
One anticapsid (p26) mouse monoclonal antibody was developed after immunization with recombinant p26 Gag protein and was tested for reactivity with different HIV-1 and HIV-2 isolates by ELISA and Western blot analysis. This antibody, named R26.1, reacted with all HIV-2 isolates tested and with recombinant p26 proteins, but no HIV-1 isolates. The epitope of antibody R26.1 was mapped to residues 50-71 in the N-terminal domain of the capsid protein, a highly conserved region in all HIV-2 isolates sequenced to date. This monoclonal antibody may be useful for the detection of HIV-2, and for the discrimination between HIV-1 and HIV-2 infections. Likewise, the identified epitope may be useful for the detection of p26 antibodies in HIV-2-infected individuals.
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Affiliation(s)
- J M Marcelino
- INETI, Departamento de Biotecnologia, UTPAM, Lisbon, Portugal
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46
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Abstract
A direct comparison of different HIV antigen assays is very helpful in making an informed choice, not only for the testing laboratories but also for healthcare workers in the developing world who are looking for reliable and inexpensive tests/methods in the follow-up of their treated patients. As a follow-up to the study published previously [Fransen K., Martens G., Stynen D., Goris A., Nys P., Nkengasong J., Heyndrickx L., Janssens W., van der Groen G., 1997. J. Med. Virol. 53, 31--35] where only two tests have been compared, four different commercial methods for HIV antigen determination in plasma and supernatant of cell cultures have now been evaluated on a limited sample size (88): COULTER HIV-1 p24 Antigen Assay (Coulter), (Test 1) INNOTEST HIV Antigen mAb (Innogenetics) (Test 2), Genetic Systems HIV-1 Ag EIA (Sanofi-Pasteur(1)) (Test 3) and VIDAS HIV P24 II (bioMérieux) (Test 4). Of the four tests used in this study, Test 2 was by far the most sensitive test. In a population of 88 follow-up samples from 35 different patients representing all stages of infection, the test detected confirmed p24 antigen at least once in 85.7% (30/35) of these patients, versus Test 3 in 74.3% (26/35), Test 4 in 71.4% (25/35), and Test 1 in 48.6% (17/35) of the patients. Test 2 detected confirmed p24 antigen in 84.9% of the follow-up samples, followed by Test 4 (65.9%), Test 3 (64.8%) and Test 1 (39.8%). Finally, Test 2 also proved best for detecting genetically diverse isolates.
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Affiliation(s)
- K Fransen
- Institute of Tropical Medicine, Nationalestraat 155, 2000 Antwerpen, Belgium.
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47
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Klein D, Leutenegger CM, Bahula C, Gold P, Hofmann-Lehmann R, Salmons B, Lutz H, Gunzburg WH. Influence of preassay and sequence variations on viral load determination by a multiplex real-time reverse transcriptase-polymerase chain reaction for feline immunodeficiency virus. J Acquir Immune Defic Syndr 2001; 26:8-20. [PMID: 11176264 DOI: 10.1097/00126334-200101010-00002] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Determination of retroviral load is an important tool in the investigation of the success of therapeutic or vaccination trials in patients infected with lentiviruses such as HIV, or with their simian (SIV) or feline (FIV) counterparts. We have developed an one-tube quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay based on the ABI Prism 7700 Sequence Detection System (TaqMan) to quantify the viral load of FIV-infected cats. Two different primer/probe systems were designed to detect a broad range of clade A FIV isolates. Both systems are characterized by excellent reproducibility, high sensitivity, and a wide range of quantification. As a consequence of this improved precision in the quantitative RT-PCR, preassay variations have greater impact on the accuracy of the viral load estimation. To compensate for these variations, we improved the assay and developed a multiplex real-time RT-PCR, which allows simultaneous calculation of the viral copy number and the individual recovery rate in an one-tube reaction. This enables the rapid and accurate calculation of copy number independent of preassay variations. In further studies, two additional real-time RT-PCR assays were designed and used to investigate the influence of sequence variations in the binding regions for either the primers or probe. Sequence mismatches in this region had a significant effect (up to 4 logarithmic decades) on reaction efficiency. In view of the inherent variability of retroviral sequences, these results underline the necessity to check reaction efficiencies before determining viral load.
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Affiliation(s)
- D Klein
- Institute of Virology, University of Veterinary Sciences, Vienna, Austria.
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48
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Influence of Preassay and Sequence Variations on Viral Load Determination by a Multiplex Real-Time Reverse Transcriptase–Polymerase Chain Reaction for Feline Immunodeficiency Virus. J Acquir Immune Defic Syndr 2001. [DOI: 10.1097/00042560-200101010-00002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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49
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Schüpbach J, Tomasik Z, Nadal D, Ledergerber B, Flepp M, Opravil M, Böni J. Use of HIV-1 p24 as a sensitive, precise and inexpensive marker for infection, disease progression and treatment failure. Int J Antimicrob Agents 2000; 16:441-5. [PMID: 11118855 DOI: 10.1016/s0924-8579(00)00272-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
HIV RNA is an acknowledged marker of disease activity and predictive of progression, while the p24 antigen is considered unsuitable. This is at odds with the fact that viral pathogenesis is usually mediated by proteins. One might expect that p24, if analyzed properly, might even be superior to RNA. This hypothesis was investigated in clinical studies using a sensitive and precise p24 test (heat-mediated immune complex dissociation with signal amplification-boosted ELISA). This test was as sensitive and specific as the polymerase chain reaction (PCR) for viral RNA (200-400 copy detection), an overall better predictor of CD4 decline and survival, while RNA prevailed in predicting AIDS. The lower costs of p24 testing also permit a closer monitoring of patients with an earlier detection of anti-retroviral treatment failures.
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Affiliation(s)
- J Schüpbach
- Swiss National Center for Retroviruses, University of Zurich, Gloriastrasse 30, CH-8028 Zurich, Switzerland.
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50
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Hofmann-Lehmann R, Swenerton RK, Liska V, Leutenegger CM, Lutz H, McClure HM, Ruprecht RM. Sensitive and robust one-tube real-time reverse transcriptase-polymerase chain reaction to quantify SIV RNA load: comparison of one- versus two-enzyme systems. AIDS Res Hum Retroviruses 2000; 16:1247-57. [PMID: 10957722 DOI: 10.1089/08892220050117014] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Plasma viral RNA load is a key parameter in disease progression of lentiviral infections. To measure simian immunodeficiency virus (SIV) RNA loads, we have established a quantitative one-tube assay based on TaqMan chemistry. This real-time reverse transcriptase-polymerase chain reaction (RT-PCR) has advantages compared with previous methods, such as higher sensitivity, shorter time consumption, and low risk of cross-contamination. The sensitivity of the assay was optimized by comparing different enzyme systems. The one-enzyme protocol using rTth DNA polymerase was superior to two assays employing two enzymes. It detects 100% of the samples containing four copies of RNA transcript and allows quantification of viral RNA loads over an 8-log unit dynamic range. As few as 50 copies per milliliter of plasma can be detected within RNA extracted from 140 microl of plasma. This is especially relevant in studies employing neonatal macaques, from which only small volumes of blood can be sampled, and in studies in which low viral RNA loads are expected. Because of the use of rTth DNA polymerase, DNA contamination can be avoided by carryover prevention with uracil N-glycosylase (UNG). We demonstrate that for optimization of real-time PCR sensitivity, not only concentrations of different reagents but also different enzyme systems must be evaluated. Our assay facilitates and enhances the quantification of plasma RNA loads, a critical parameter for many studies, including evaluations of vaccine candidates or antiviral regimens.
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