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Wall T. A case of a false positive HIV antigen/antibody screen in a pregnant woman at delivery and the clinical importance of reviewing signal-to-cutoff ratio values. IDCases 2023; 33:e01819. [PMID: 37645530 PMCID: PMC10461126 DOI: 10.1016/j.idcr.2023.e01819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 08/31/2023] Open
Abstract
We present a unique case not previously touched upon in the literature, and its ensuing management, of a falsely reactive HIV (human immunodeficiency virus) screening test which resulted in a woman during active labor, hours after rupture of membranes. The patient was screened for HIV using the ARCHITECT 4th generation HIV 1 and 2 Antigen/Antibody (Ag/Ab) Combo assay, and the results were repeatedly reactive. A cesarean delivery was recommended, and the patient received intrapartum antiretroviral therapy. Due to rapid progression of labor, the infant was delivered vaginally and received multiple doses of antiretroviral therapy. For confirmation, a viral load PCR test was obtained which resulted undetectable, and it was concluded that the screening results were falsely positive. While the cause of the inaccurate screening result is still unclear, a COVID-19 vaccination in close proximity to the delivery remains suspicious. Four months after delivery, the patient's screening test was no longer reactive.
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Affiliation(s)
- Talia Wall
- Touro College of Pharmacy, United States of America
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2
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Shi Z, Cao L, Luo J, Zhou G, Zuo Q, Liu X, Hu Y, Tian H, Zheng H. A chemiluminescent magnetic microparticle immunoassay for the detection of antibody against African swine fever virus. Appl Microbiol Biotechnol 2023; 107:3779-3788. [PMID: 37099055 DOI: 10.1007/s00253-023-12518-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/13/2023] [Accepted: 04/04/2023] [Indexed: 04/27/2023]
Abstract
The p30 protein is abundantly expressed in the early stage of African swine fever virus (ASFV) infection. Thus, it is an ideal antigen candidate for serodiagnosis with the use of an immunoassay. In this study, a chemiluminescent magnetic microparticle immunoassay (CMIA) was developed for the detection of antibodies (Abs) against ASFV p30 protein in porcine serum. Purified p30 protein was coupled to magnetic beads, and the experimental conditions including concentration, temperature, incubation time, dilution ratio, buffers, and other relevant variables were evaluated and optimized. To evaluate the performance of the assay, a total of 178 pig serum samples (117 negative and 61 positive samples) were tested. According to receiver operator characteristic curve analysis, the cut-off value of the CMIA was 104,315 (area under the curve, 0.998; Youden's index, 0.974; 95% confidence interval: 99.45 to 100%). Sensitivity results showed that the dilution ratio of p30 Abs in ASFV-positive sera detected by the CMIA is much higher when compared to commercial blocking ELISA kit. Specificity testing showed that no cross-reactivity was observed with sera positive for other porcine disease viruses. The intraassay coefficient of variation (CV) was < 5%, and the interassay CV was < 10%. The p30-magnetic beads could be stored at 4 °C for more than 15 months without loss of activity. The kappa coefficient between CMIA and INGENASA blocking ELISA kit was 0.946, showing strong agreement. In conclusion, our method showed superiority with high sensitivity, specificity, reproducibility, and stability and potentialized its application in the development of a diagnostic kit for the detection of ASF in clinical samples. KEY POINTS: • ASFV tag-free p30 was successfully purified. • High sensitivity, specificity, relatively simple, and time-saving to detect antibody against ASFV were developed. • The development of CMIA will help the clinical diagnosis of ASFV and will be useful for large-scale serological test.
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Affiliation(s)
- Zhengwang Shi
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, 730070, China
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China
| | - Liyan Cao
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China
| | - Juncong Luo
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China
| | - Gaijing Zhou
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China
| | - Qingshan Zuo
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China
| | - XiangTao Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China
| | - Yonghao Hu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, 730070, China.
| | - Hong Tian
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China.
| | - Haixue Zheng
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China.
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Development and evaluation of a chemiluminescence immunoassay for detecting tropical theileriosis. Acta Trop 2020; 202:105245. [PMID: 31676457 DOI: 10.1016/j.actatropica.2019.105245] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 10/24/2019] [Accepted: 10/24/2019] [Indexed: 11/23/2022]
Abstract
Tropical theileriosis is a tick-borne lymphoproliferative disease of cattle caused by the apicomplexan parasite Theileria annulata, and leads to substantial economic losses to the livestock industry worldwide. Although various enzyme-linked immunosorbent assays (ELISAs) have been established to detect antibodies against T. annulata infection, a specific, rapid and reliable diagnostic assay is urgently needed for prevention and control of the disease. In the present study, a chemiluminescence immunoassay (CLIA) was developed based on the subtelomeric variable secreted protein (SVSP) of T. annulata as a sero-diagnostic antigen. Following optimization of the CLIA working parameters, the working time of the method was less than 4.5 h. The sensitivity and specificity of the established CLIA was 98.8% and 97.5%, respectively, when the cut-off value of the percent positive (PP) was 26.1% for detecting serum samples (n = 242 T. annulata positive sera, n = 158 T. annulata negative sera). After comparing 180 serum samples from Gansu province, China, the concordance rate between the CLIA and a published rSpm2 ELISA method was 72.8%. In addition, 565 serum samples of cattle collected between 2017 and 2018 from four provinces in China were detected by the CLIA, and the seroprevalence for T. annulata ranged from 53.3% to 67.3% in these regions. Our findings demonstrated that the CLIA has high specificity, sensitivity and reliability, and could be used as a rapid detection assay for epidemiological investigations of T. annulata infection.
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Fonseca THS, Faria AR, Leite HM, da Silveira JAG, Carneiro CM, Andrade HM. Chemiluminescent ELISA with multi-epitope proteins to improve the diagnosis of canine visceral leishmaniasis. Vet J 2019; 253:105387. [PMID: 31685139 DOI: 10.1016/j.tvjl.2019.105387] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/16/2019] [Accepted: 09/17/2019] [Indexed: 11/30/2022]
Abstract
Diagnosing canine visceral leishmaniasis (CVL) is difficult because clinical signs of the disease are non-specific and a many infected animals in endemic areas, as in Brazil, are asymptomatic. Serological tests are the most common diagnostic methods employed, but most have limitations. For this reason, the implementation of a rapid, sensitive, and specific diagnostic test for CVL has become increasingly important. In this study, we adapted a chemiluminescent enzyme-linked immunosorbent assay (CL ELISA), using two multi-epitope recombinant proteins (PQ10 and PQ20) and a crude Leishmania antigen produced using promastigotes of L. infantum, as antigens to detect CVL infection in animals from Belo Horizonte. To investigate cross-reactions, samples from dogs with other infections (babesiosis, ehrlichiosis and Trypanosoma cruzi) were tested. Assay performance validations were conducted to analyse parameters such as variability, reproducibility, and stability. CL ELISA sensitivity/specificity with PQ10 antigen was 93.1%/80.0%; with the PQ20 protein 93.1%/96.6%; and with the crude antigen 75%/73.3%. Inter-assay variability and inter-operator coefficient of variation were <7% and <15%, with PQ10 and PQ20, respectively. The accuracy of the CL ELISA was classified as excellent for PQ10 (AUC = 0.95) and PQ20 (AUC = 0.98) and moderate for the crude antigen (AUC = 0.77). The kappa score for qualitative agreement between two plate lots was excellent for PQ10 (0.89) and good for PQ20 (0.65). PQ20 remained more stable than PQ10. The CL ELISA with recombinant proteins is a promising tool to diagnose CVL.
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Affiliation(s)
- T H S Fonseca
- Laboratório de Leishmanioses, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - A R Faria
- Laboratório de Leishmanioses, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - H M Leite
- Laboratório de Leishmanioses, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - J A G da Silveira
- Laboratório de Protozoologia Veterinária, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - C M Carneiro
- Departamento de Análises Clínicas, Escola de Farmácia, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brazil
| | - H M Andrade
- Laboratório de Leishmanioses, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
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Wang L, Wang J, Tian X, Ruan J, Yu Y, Yan F. Sample-to-cutoff ratios using Architect HIV Ag/Ab Combo: The influence with the results of supplemental tests and optimal cutoff value to predict HIV infection. J Clin Lab Anal 2019; 33:e22866. [PMID: 30803030 PMCID: PMC6595311 DOI: 10.1002/jcla.22866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/18/2018] [Accepted: 01/31/2019] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The Architect HIV Ag/Ab Combo has excellent performance for HIV screening; however, the false-positive rate (FPR) was high in low HIV prevalence setting. OBJECTIVES The purpose of this study was to analyze the influence of sample-to-cutoff (s/co) ratios by Architect HIV Ag/Ab Combo with the results of confirmatory test and explore the potential utility of s/co to predict HIV infection. METHODS A retrospective review on Architect HIV Ag/Ab Combo reactive results was performed at a teaching hospital in Xi'an. The s/co values in different groups, that is, true positives (TP) and false positives (FP), different Western blotting (WB) bands among WB-positive cases, were compared. The receiver operating characteristic curve (ROC) analysis was used to determine the optimal cutoff value for predicting HIV infection. RESULTS During the study period, 219 out of 84 702 patients were reactive by ARCHITECT with a 0.0992% of HIV prevalence and a 56.25% of FPR. The mean s/co ratios in TP were significantly higher than that in FP (458.15 vs 3.11, P < 0.0001). Among the WB-positive cases, the s/co ratios increased significantly with the increase in the number of bands, P = 0.0065. The optimal cutoff (24.44) by ROC analysis can provide the highest sum of sensitivity (100%) and specificity (100%) with no FP results. CONCLUSIONS For Architect HIV Ag/Ab Combo, the FPR is reduced when s/co ratios increase, and the s/co ≥24.44 may be reliable to predict HIV infection.
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Affiliation(s)
- Linchuan Wang
- The First Affiliated Hospital of Xi’an Jiaotong UniversityXi’anChina
| | - Jing‐Yuan Wang
- The First Affiliated Hospital of Xi’an Jiaotong UniversityXi’anChina
| | - Xu‐Dong Tian
- The First Affiliated Hospital of Xi’an Jiaotong UniversityXi’anChina
| | - Jin‐xiong Ruan
- The First Affiliated Hospital of Xi’an Jiaotong UniversityXi’anChina
| | - Yan Yu
- Hong‐Hui HospitalXi’an Jiaotong University College of MedicineXi’anChina
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Evaluation of the Architect HIV Ag/Ab Combo Assay in a low-prevalence setting: The role of samples with a low S/CO ratio. J Clin Virol 2018; 103:43-47. [PMID: 29635210 DOI: 10.1016/j.jcv.2018.04.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/20/2018] [Accepted: 04/03/2018] [Indexed: 11/20/2022]
Abstract
BACKGROUND The Architect HIV Ag/Ab Combo Assay, a fourth-generation ELISA, has proven to be highly reliable for the diagnosis of HIV infection. However, its high sensitivity may lead to false-positive results. OBJECTIVES To evaluate the diagnostic performance of Architect in a low-prevalence population and to assess the role of the sample-to-cutoff ratio (S/CO) in reducing the frequency of false-positive results. STUDY DESIGN We conducted a retrospective study of samples analyzed by Architect between January 2015 and June 2017. Positive samples were confirmed by immunoblot (RIBA) or nucleic acid amplification tests (NAATs). Different S/CO thresholds (1, 2.5, 10, 25, and 100) were analyzed to determine sensitivity, specificity, and negative and positive predictive values (NPV, PPV). ROC analysis was used to determine the optimal S/CO. RESULTS A total of 69,471 samples were analyzed. 709 (1.02%) were positive by Architect. Of these, 63 (8.89%) were false-positive results. Most of them (93.65%) were in samples with S/CO < 100. However, most confirmations by NAATs (12 out of 19 cases) were also recorded for these samples. The optimal S/CO was 2.5, which provided the highest area under the ROC curve (0.9998) and no false-negative results. With this S/CO, sensitivity and specificity were 100.0%, and PPV and NPV were 95.8% and 100.0%, respectively. In addition, the frequency of false-positive results decreased significantly to 4.15%. CONCLUSIONS Although Architect generates a relatively high number of false-positive results, raising the S/CO limit too much to increase specificity can lead to false-negative results, especially in newly infected individuals.
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Comparison of electrochemiluminescence and ELISA methods in the detection of blood borne pathogens in Gabon. Asian Pac J Trop Biomed 2017. [DOI: 10.1016/j.apjtb.2017.08.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Chemiluminescence Immunoassay for the Detection of Antibodies against the 2C and 3ABC Nonstructural Proteins Induced by Infecting Pigs with Foot-and-Mouth Disease Virus. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00153-17. [PMID: 28592628 DOI: 10.1128/cvi.00153-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/01/2017] [Indexed: 11/20/2022]
Abstract
The potential diagnostic value of chemiluminescence immunoassays (CLIAs) has been accepted in recent years, although their use for foot-and-mouth disease (FMD) diagnostics has not been reported. Full-length 3ABC and 2C proteins were expressed in bacteria and purified by affinity chromatography to develop a rapid and accurate approach to distinguish pigs infected with foot-and-mouth disease virus (FMDV) from vaccinated pigs. The recombinant proteins were then used as antigens to develop two CLIAs for the detection of antibodies against nonstructural viral proteins. The diagnostic performance of the two assays was compared by analyzing serum from pigs (naive pigs, n = 63; vaccinated, uninfected pigs, n = 532; naive, infected pigs, n = 117) with a known infection status. The 3ABC-2C CLIA had a higher accuracy rate, with a diagnostic sensitivity of 100% and a diagnostic specificity of 96.5%, than the 3ABC CLIA, which had a diagnostic sensitivity of 95.7% and a diagnostic specificity of 96.0%. The results of the 3ABC-2C CLIA also had a high rate of concordance with those of two commercial FMDV enzyme-linked immunosorbent assay (ELISA) kits used to assess serum collected from 962 pigs in the field (96.2% and 97.8%, respectively). The 3ABC-2C CLIA detected infection in serum samples from infected pigs earlier than the commercial ELISA kits. In addition, the 3ABC-2C CLIA produced results within 15 min. On the basis of these findings, the 3ABC-2C CLIA could serve as the foundation for the development of penside FMD diagnostics and offers an alternative method to detect FMDV infections.
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Liang S, Deng G, Zhou S, Zeng J, Tan W, Yuan X. A retrospective analysis of the application of the Elecsys ® HIV combi PT assay in southern China. J Clin Lab Anal 2017. [PMID: 28650079 DOI: 10.1002/jcla.22287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Fourth-generation HIV assays have been implemented worldwide as a screening test for many years. Understanding the performance of fourth-generation assay in low HIV prevalence region is pivotal to interpret the test result correctly. In this study, retrospective analysis was used to evaluate application of the Elecsys® HIV combi PT assay. METHODS A total of 85 043 specimens from a low prevalence setting were detected between June 2013 and October 2015. We evaluated the false-positive rate (FPR), specificity, and positive predictive value (PPV). RESULTS The specificity between male and female were 99.85% and 99.82%, respectively. The PPV on male (50.75%) was higher than female (17.05%) significantly, while the FPR was 0.15% and 0.18%. The gap between false-positive (median: 1.83, [IQR]: 1.30, 3.38) and confirmed-positive (median: 407.5, [IQR]: 184.2, 871.7) is enormous. The highest s/co ratio for false-positive cases was 85.45, while the lowest s/co ratio for confirmed-positive cases was 59.68. Various reasons were attributed to false-positive cases. CONCLUSION Optimal cutoff value is needed to be set to reduce the false-positive cases and predict the final status of HIV infection reliably. Retrospective analysis will help us to understand more about diagnosis of HIV.
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Affiliation(s)
- Shaocong Liang
- Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, GuangZhou, GuangDong, China
| | - Guihua Deng
- Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, GuangZhou, GuangDong, China
| | - Shaosong Zhou
- Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, GuangZhou, GuangDong, China
| | - Jing Zeng
- Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, GuangZhou, GuangDong, China
| | - Weiqing Tan
- Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, GuangZhou, GuangDong, China
| | - Xiaopeng Yuan
- Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, GuangZhou, GuangDong, China
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Chacón L, Mateos ML, Holguín Á. Relevance of cutoff on a 4th generation ELISA performance in the false positive rate during HIV diagnostic in a low HIV prevalence setting. J Clin Virol 2017; 92:11-13. [PMID: 28501753 DOI: 10.1016/j.jcv.2017.04.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/20/2017] [Accepted: 04/25/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND Despite the high specificity of fourth-generation enzyme immunoassays (4th-gen-EIA) for screening during HIV diagnosis, their positive predictive value is low in populations with low HIV prevalence. Thus, screening should be optimized to reduce false positive results. OBJECTIVES The influence of sample cutoff (S/CO) values by a 4th-gen-EIA with the false positive rate during the routine HIV diagnosis in a low HIV prevalence population was evaluated. STUDY DESIGN A total of 30,201 sera were tested for HIV diagnosis using Abbott Architect® HIV-Ag/Ab-Combo 4th-gen-EIA at a hospital in Spain during 17 months. Architect S/CO values were recorded, comparing the HIV-1 positive results following Architect interpretation (S/CO≥1) with the final HIV-1 diagnosis by confirmatory tests (line immunoassay, LIA and/or nucleic acid test, NAT). ROC curve was also performed. RESULTS Among the 30,201 HIV performed tests, 256 (0.85%) were positive according to Architect interpretation (S/CO≥1) but only 229 (0.76%) were definitively HIV-1 positive after LIA and/or NAT. Thus, 27 (10.5%) of 256 samples with S/CO≥1 by Architect were false positive diagnose. The false positive rate decreased when the S/CO ratio increased. All 19 samples with S/CO ≤10 were false positives and all 220 with S/CO>50 true HIV-positives. The optimal S/CO cutoff value provided by ROC curves was 32.7. No false negative results were found. CONCLUSIONS We show that very low S/CO values during HIV-1 screening using Architect can result HIV negative after confirmation by LIA and NAT. The false positive rate is reduced when S/CO increases.
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Affiliation(s)
- Lucía Chacón
- Molecular Epidemiology Laboratory, Microbiology Department, Ramón y Cajal Health Research Institute (IRYCIS), Spain
| | | | - África Holguín
- Molecular Epidemiology Laboratory, Microbiology Department, Ramón y Cajal Health Research Institute (IRYCIS), Spain.
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Kim DH, Bong JH, Yoo G, Chang SY, Chang YW, Kang MJ, Jose J, Pyun JC. A magnetite suspension-based washing method for immunoassays using Escherichia coli cells with autodisplayed Z-domains. Enzyme Microb Technol 2016; 92:1-8. [PMID: 27542738 DOI: 10.1016/j.enzmictec.2016.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/07/2016] [Accepted: 06/08/2016] [Indexed: 10/21/2022]
Abstract
Escherichia coli cells with autodisplayed Z-domains have been used for immunoassays of specific target analytes. In this study, a magnetite suspension was used for the washing step in immunoassays of E. coli cells with autodisplayed Z-domains. This approach enhanced the washing conditions for these immunoassays by determining (1) the optimal concentration of the magnetite suspension, (2) the capacity of the magnetite suspension-based washing method to recover E. coli cells, and (3) the level at which the activity of autodisplayed Z-domains is maintained. In immunoassays of C-reactive protein (CRP), the immunoassay incorporating the magnetite suspension-based washing method showed a sensitivity and limit of detection considerably higher than those of the conventional centrifugation-based washing method. The results indicated that immunoassays incorporating the magnetite suspension-based washing method are effective for medical diagnoses based on CRP assay.
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Affiliation(s)
- Do-Hoon Kim
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, Korea
| | - Ji-Hong Bong
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, Korea
| | - Gu Yoo
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, Korea
| | - Seo-Yoon Chang
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, Korea
| | - Young Wook Chang
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, Korea
| | - Min-Jung Kang
- Korea Institute of Science and Technology, Seoul, Korea
| | | | - Jae-Chul Pyun
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, Korea.
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