HIV抗体筛查试验阳性-确证试验阴性标本的分析

目的了解HIV抗体筛查试验假阳性现象的特点及引起假阳性反应的原因。方法对2004～2009年本实验室常规监测检测中筛查试验阳性-确证试验阴性标本的相关资料进行分析。结果394例筛查试验阳性-确证试验阴性标本主要来源于没有或甚少高危行为的各类普通人群;采用"明胶颗粒凝集试剂(PA)+ELISA"或双ELISA试剂组合检测,83%以上为一阴一阳结果,近70%的标本ELISAS/CO值在1～4之间;采用"吉比爱ELISA+第3代梅里埃ELISA"或"吉比爱ELISA+第4代梅里埃ELISA"组合检测,S/CO值同处于1～6范围的标本分别占78.95%和64.0%。结论HIV抗体筛查检测假阳性存在主、客观原因;实验室应采取应对措施最大限度地保证结果的准确以及对检测结果进行正确的解释。     

136份初筛抗-HIV1+2阳性而复检阴性标本的分析

目的了解山东省历年来艾滋病病毒(HIV)抗体检测中筛查试验假阳性结果的真实情况,更加合理地开展HIV抗体日常检测。方法检测及结果判断按《全国艾滋病检测技术规范》进行,对比分析HIV抗体筛查试验为阳性而免疫印迹试验(WB)为阴性的标本的结果以及相关资料。结果136份筛查试验为阳性反应、WB确认为HIV抗体阴性的标本,占所有送检标本的6.70%,占筛查试验阳性标本的13.39%。136份标本中,明胶颗粒凝集试验(PA)阳性的119份,占87.50%;酶联免疫吸附试验(ELISA)阳性33份,占24.26%,S/CO值平均为0.8005(0.2319~5.544)。结论日常检测必须遵从先筛查再确认的检测程序,筛查试验阳性的不能直接出HIV抗体阳性报告,应确认后再出。     

两种不同初筛酶联免疫吸附试验试剂联合检测以替代艾滋病病毒抗体蛋白印迹试验确认检测的对比分析

目的　为评价两种不同初筛酶联免疫吸附试验 (ELISA)试剂联合检测艾滋病病毒 (HIV)抗体的可靠性 ,以替代艾滋病病毒 (HIV)蛋白印迹 (Westernblotting ,WB)确认法。 方法　79份初检为HIV抗体阳性的吸毒人员血清 ,重新统一用两种抗体初筛ELISA试剂 (Vironostika○RHIVUni FormⅡ plus 0和UBIHIV 1 / 2EIA)进行复测 ,之后随机选择前 51份样品进一步做WB确认 ,并做对比分析。 结果　51份血清中 ,有 49份样品 2次初筛复测时至少有 1次复测的结果显示为S/CO≥ 6 ,它们的WB确认结果均为HIV抗体阳性 ;其余的 2份样品 2次初筛复测时 ,其S/CO均 <6 ,但其中 1份 (样品“0 5”)的WB结果为HIV抗体阴性 ,1份 (样品“584”)为HIV抗体阳性。确认为HIV抗体阴性的样品“0 5” ,在整个初筛的 3次检测中曾 2次出现过S/CO >1 ;确认为HIV抗体阳性的样品“584” ,虽然 3次初筛检测中S/CO值均 >1 ,但因本试验中 2次复测得到的S/CO都 <6 ,因而其确认结果亦显示出较少抗原带 ,即只有p2 4和Gp1 60。 结论　两种不同原理的ELISA试剂 (最好为进口试剂 )联合检测HIV抗体可替代WB确认法 ,以监测具有一定HIV流行率的风险人群 (如哨点监测人群 )的HIV/艾滋病疫情。报告为HIV抗体阳性的临界判断指标采用 2次初筛S/CO≥ 6应是可靠的 ;初筛中     

HIV抗体筛查试剂联合检测替代免疫印迹法的对比分析

目的探讨用两种不同厂家或原理的HIV抗体初筛试剂联合检测,以替代免疫印迹法(WB),用于检测某些高危人群或特殊人群。方法用包括快速检测和酶联免疫吸附试验(ELISA)试剂在内的9种HIV抗体筛查试剂,对200份样本进行联合检测,对任意一种试剂检测阳性的样本进行WB检测。结果ELISA初筛有阳性反应(S/CO值>1)的样本,WB确认阳性率为81.93%。初筛阳性且有1种ELISA试剂S/CO值>6的样本,WB确认阳性率为100%。两种快速试剂检测均为阳性反应的,WB确认阳性率为100%。结论可以用两次ELISA、两种快速试剂或一种快速试剂加一种ELISA试剂联合检测替代WB。     

HIV抗体检测替代策略在全人群中推广应用的可行性研究

目的评价艾滋病病毒(HIV)抗体检测替代策略在各类人群中检测HIV抗体的可靠性,探讨HIV抗体替代策略在全人群中推广的可行性。方法对1 040份筛查阳性的样本,用6种不同的快速试剂、1种酶联免疫吸附试验(ELISA)试剂及蛋白印迹法(WB)同时进行检测,对WB不确定样本做病毒载量(VL)检测,对检测结果进行比较。结果 1 040份筛查阳性样本中,WB检测结果为阳性的有1 007份,当2种快速试剂检测结果为阳性,ELISA试剂检测结果 S/CO≥1时,一致性为100%;WB检测结果为不确定,且VL检测结果为阳性的有20份,当2种快速试剂检测结果为阳性,ELISA试剂检测结果 S/CO≥6时,一致性为100%;以上结果在各类人群中均一致。结论当2种快速试剂检测结果为阳性,且ELISA试剂检测结果 S/CO≥6时,与WB或VL检测结果一致性达到100%,可以替代WB确证检测。在保证检测试剂质量的情况下,将HIV抗体检测替代策略向全人群推广应用是可行的。     

HIV1+2抗体筛查阳性与免疫印迹试验结果分析

目的 对比HIV1+2抗体筛查试验阳性与免疫印迹蛋白试验（WB）结果，探讨筛查与确认实验结果之间的关系，为HIV抗体诊断提供科学依据。方法 按照《全国艾滋病检测技术规范》2020修订版对河南省漯河市艾滋病筛查实验室送检疑似样本复核，采用酶联免疫吸附试验（ELISA）和快速胶体金试验（RT）两种方法检测，经复检后任何1种筛查试验结果呈现HIV阳性反应需进行WB试验，2种试剂复核结果与WB结果比较研究。结果 复检1 564份疑似样本经WB确认，1 420份呈现HIV型抗体阳性（90.79%）,74份阴性（4.73%）、70份不确定（4.48%）。2种筛查试验与WB结果的阳性符合率为90.93%和91.94%。结论 复核实验中酶联免疫试验吸光度值/临界值（S/CO）值越高，RT检测带越深，WB试验结果的阳性率也越高，HIV抗体阳性确认结果以WB为准。ELISA、RT存在一定的假阳性，而WB试验结果为HIV抗体阴性或不确定。     

安阳市HIV抗体筛查阳性样本确认结果及条带分析

目的了解安阳市艾滋病病毒(HIV)抗体检测中,筛查试验阳性结果的准确性,以便更加合理地开展HIV抗体日常检测。方法按《全国艾滋病检测技术规范》要求进行操作,然后对比分析酶联免疫吸附试验(ELISA)筛查HIV抗体阳性者与蛋白免疫印迹试验(WB)结果的一致性。结果经两种ELISA试剂筛查HIV抗体呈阳性或一阴一阳的352份血清标本,经WB确认阳性331例,阳性率为94.03%;21例为不确定,占5.97%。WB带型≥7条带的共计328例,占99.09%;6条带的3例,占0.91%。结论艾滋病筛查实验和确认实验结果一致性高。筛查实验存在一定的假阳性,阳性样本必须进行确证实验,对确证实验不确定的样本需进行随访。     

HIV抗体检测替代策略Ⅱ在云南省应用的可行性探讨

目的 评价用艾滋病病毒(HIV)抗体检测替代策略Ⅱ检测HIV抗体的可靠性,探讨HIV抗体检测替代策略Ⅱ在云南省应用的可行性.方法 对所有筛查阳性标本同时用替代策略Ⅱ及免疫印迹法(WB)检测,并对检测.结果 进行比较.结果 915份初筛阳性的标本中,两种酶联免疫吸附试验(ELISA)检测.结果 阳性且S/CO≥6的有854份,明胶颗粒凝集试验(PA)检测.结果 均为阳性,WB确认为阳性,符合率为100%;两种ELISA法检测.结果 均阳性,但其中1种或2种S/CO在1.0～5.9之间的共有61份,经WB确认检测,其中32份为阳性,28份为不确定,1份为阴性.结论 两种ELISA试剂和第三种高特异性筛查试剂联合检测HIV抗体,可以替代90%以上的WB确认检测.当两种ELISA法检测.结果 S/CO＞6,且第三种高特异性筛查试剂检测.结果 为阳性时,与WB确认检测.结果 符合率是100%;当1种或2种ELISA法检测.结果 1＜S/CO＜6时,三种方法与WB确认检测.结果 符合率仅为52.5%.因此,在使用HIV抗体替代策略Ⅱ时,应同时考虑ELISA法的反应强度(S/CO值)和其他筛查方法的.结果 .在综合考虑了以上因素后,HIV抗体检测替代策略Ⅱ在云南省应用是可行的.     

酶联荧光分析法在HIV感染筛查中的应用

目的分析酶联荧光分析法(ELFA)检测艾滋病病毒(HIV)阳性反应样本与蛋白印迹试验(WB)确证结果的相关性,探讨ELFA在HIV感染筛查中的应用。方法回顾2014年6月至2016年3月,杭州市各筛查实验室上送样本中,ELFA检测HIV抗体阳性反应样本2 113例,HIVp24抗原阳性反应样本39例,用WB试验进行确证。比较ELFA阳性反应结果和WB确证结果的相关性,分析ELFA检测HIV抗体不同检测值对WB确证结果的预测性。结果 2 113例抗体阳性反应样本与WB试验结果符合率为98.25%(2 076例)。剔除46例无随访结果的样本,进一步讨论2 067例抗体阳性反应样本,ELFA法检测HIV抗体阳性预测值为97.92%(2 024例)。39例HIVp24抗原阳性反应样本首次WB确证36例(92.31%)为结果不确定,已随访的23例均确证为阳性。结论ELFA检测HIV抗体抗原结果直观,抗体阳性反应样本和WB确证试验有很好的相关性和预测性,是HIV抗体检测S/CO比值替代策略中一种较好的检测方法。     

天津市HIV抗体检测中的替代策略研究

目的分析天津市2007-2009年人群HIV抗体检测数据,确定替代策略应用方案。方法对于接收的天津市艾滋病检测筛查实验室送检的1 636份样品,依据《全国艾滋病检测技术规范（2004年版）》规定的检测流程与方法进行HIV抗体确证。结果 2007-2009年共有1 039份样品经确证为HIV抗体阳性,进行艾滋病疫情报告例数为690例。ELISA S/CO≥6且快速检测阳性的1 028份样品,确证结果均为阳性。ELISA与快速检测结果不一致的124份样品,无确证结果为阳性者。结论在HIV低流行区将替代策略引入日常HIV抗体筛查检测,可以提高检测效率。通过身份信息核查,可以有效避免对继往感染者的重复确证。     

Combining Multiple Assays Improves Detection and Serotyping of Foot-and-Mouth Disease Virus. A Practical Example with Field Samples from East Africa

Multiple serotypes and topotypes of foot-and-mouth disease virus (FMDV) circulate in endemic areas, posing considerable impacts locally. In addition, introductions into new areas are of great concern. Indeed, in recent years, multiple FMDV outbreaks, caused by topotypes that have escaped from their original areas, have been recorded in various parts of the world. In both cases, rapid and accurate diagnosis, including the identification of the serotype and topotype causing the given outbreaks, plays an important role in the implementation of the most effective and appropriate measures to control the spread of the disease. In the present study, we describe the performance of a range of diagnostic and typing tools for FMDV on a panel of vesicular samples collected in northern Tanzania (East Africa, EA) during 2012–2018. Specifically, we tested these samples with a real-time RT-PCR targeting 3D sequence for pan-FMDV detection; an FMDV monoclonal antibody-based antigen (Ag) detection and serotyping ELISA kit; virus isolation (VI) on LFBKαVβ6 cell line; and a panel of four topotype-specific real-time RT-PCRs, specifically tailored for circulating strains in EA. The 3D real-time RT-PCR showed the highest diagnostic sensitivity, but it lacked typing capacity. Ag-ELISA detected and typed FMDV in 71% of sample homogenates, while VI combined with Ag-ELISA for typing showed an efficiency of 82%. The panel of topotype-specific real-time RT-PCRs identified and typed FMDV in 93% of samples. However, the SAT1 real-time RT-PCR had the highest (20%) failure rate. Briefly, topotype-specific real-time RT-PCRs had the highest serotyping capacity for EA FMDVs, although four assays were required, while the Ag-ELISA, which was less sensitive, was the most user-friendly, hence suitable for any laboratory level. In conclusion, when the four compared tests were used in combination, both the diagnostic and serotyping performances approached 100%.     

Identifying Recent HIV Infections: From Serological Assays to Genomics

In this paper, we review serological and molecular based methods to identify HIV infection recency. The accurate identification of recent HIV infection continues to be an important research area and has implications for HIV prevention and treatment interventions. Longitudinal cohorts that follow HIV negative individuals over time are the current gold standard approach, but they are logistically challenging, time consuming and an expensive enterprise. Methods that utilize cross-sectional testing and biomarker information have become an affordable alternative to the longitudinal approach. These methods use well-characterized biological makers to differentiate between recent and established HIV infections. However, recent results have identified a number of limitations in serological based assays that are sensitive to the variability in immune responses modulated by HIV subtypes, viral load and antiretroviral therapy. Molecular methods that explore the dynamics between the timing of infection and viral evolution are now emerging as a promising approach. The combination of serological and molecular methods may provide a good solution to identify recent HIV infection in cross-sectional data. As part of this review, we present the advantages and limitations of serological and molecular based methods and their potential complementary role for the identification of HIV infection recency.     

In vivo recovery with products of very high purity — assay discrepancies

Summary. In view of reports of FVIII assay discrepancies in post-infusion plasma samples depending on methods used, we compared FVIII results run by each of four different methods following infusion of rFVIII (Kogenate®). Nine persons with haemophilia A were infused with each of two lots of product. Plasma samples were obtained at baseline, and at 10 min, 30 min, 1, 2, 4, 8, 12, 14, 30 and 48 h post-infusion for measurement of FVIII. FVIII assay methods were chromogenic, and one-stage APTT using three different types of activators: micronized, silica, ellagic acid, and kaolin. The same reference plasma standard was used throughout. Results demonstrated a consistent difference in FVIII values, with chromogenic assays being considerably higher than those run by one-stage assays. The discrepancy was greatest when kaolin was the activator. These results point out the problems in attempting to determine the “correct” FVIII level in patient plasma samples following infusion of high purity FVIII preparations. Potential “pitfalls” include the standard used for defining product potency, the methods, reagents, instrumentation and standards used in assaying plasma samples and, in some instances, the characteristics of the product itself. This situation has considerable cost implications, potential impact on patient care, and makes it difficult to compare results between laboratories.     

Discrepancies in potency assessment of recombinant FVIII concentrates

Summary. Results of assays of recombinant FVIII concentrates have been reviewed over a 10-year period. Initially there was wide variability between laboratories but this was minimised by the development of standardised assay methodology, in particular the use of haemophilic plasma for pre-dilution and 1% albumin in assay buffers. Using this standardised methodology and concentrate standards, there were no major diferences in potency between one-stage, two-stage, and chromogenic assays on the two full-length recombinant FVIII concentrates. However, using a plasma standard, the chromogenic method gave much higher potencies than the one-stage method on the same concentrates, and this explains a similar discrepancy found in patients' post-infusion samples after injection of recombinant concentrates. It is suggested that concentrate standards be used for such post-infusion samples in order to minimise this discrepancy.     

Short Report: Translation of Analysis Results between Serum Ferritin Assays,Ferritin RIA Amersham™ and Abbott AxSYM™ Ferritin

The serum ferritin assays, Ferritin RIA Amersham? and Abbott AxSYM? Ferritin were compared in order to translate values from one assay to the other. Serum ferritin was analysed with both assays in 102 samples. Logarithmic transformation of the results was performed in order to stabilize the variance. The relationship between the untransformed values was most exactly expressed by a proportionality: AxSYM Ferritin = 0.873 * RIA Ferritin. Due to this proportionality, the numerical difference between the assays increases with the ferritin concentration, although the percentage difference between the assays remains constant.     

Factor VIII and thrombin generation assays: relevance to pharmacokinetic studies in haemophilia A

Summary.  This article reviews the problems associated with traditional Factor VIII (FVIII) assays in pharmacokinetic studies, and the advantages, disadvantages, and technical aspects of thrombin generation assays as a replacement or additional tool.     

Ketone bodies do not give falsely positive alcohol tests

Ketosis, as observed in diabetic ketoacidosis or secondary to hypoglycaemia, may be associated with symptoms resembling those of acute alcoholism. It is thus essential to rule out the possibility that ketone bodies cross-react with any method of ethanol determination. Two currently used methods for detecting ethanol in the expired air (Alcotest and a fuel cell electrode), and three methods for blood determination (the nitrochromic method, gas liquid chromatography, and the TDX-REA method) were examined. No cross-reaction was found in nine grossly ketotic diabetic subjects. In vitro 3-hydroxybutyrate, acetoacetate or acetone, alone (30 mmol l-1) or in association, did not cross-react in the assays studied.     

Factor XIII deficiency diagnosis: Challenges and tools

Factor XIII deficiency (FXIIID) is a rare hereditary bleeding disorder arising from heterogeneous mutations, which can lead to life‐threatening hemorrhage. The diagnosis of FXIIID is challenging due to normal standard coagulation assays requiring specific FXIII assays for diagnosis, which is especially difficult in developing countries. This report presents an overview of FXIIID diagnosis and laboratory methods and suggests an algorithm to improve diagnostic efficiency and prevent missed or delayed FXIIID diagnosis. Assays measuring FXIII activity: The currently available assays utilized to diagnose FXIIID, including an overview of their complexity, reliability, sensitivity, and specificity, as well as mutational analysis are reviewed. The use of a FXIII inhibitor assay is described. Diagnostic tools in FXIIID: Many laboratories are not equipped with quantitative FXIII activity assays, and if available, limitations in lower activity ranges are important to consider. Clot solubility tests are not standardized, have a low sensitivity, and are therefore not recommended as routine screening test; however, they are the first screening test in almost all coagulation laboratories in developing countries. To minimize the number of patients with undiagnosed FXIIID, test quality should be improved in less well‐equipped laboratories. Common country‐specific mutations may facilitate diagnosis through targeted genetic analysis in reference laboratories in suspected cases. However, genetic analysis may not be feasible in every country and may miss spontaneous mutations. Centralized FXIII activity measurements should also be considered. An algorithm for diagnosis of FXIIID including different approaches dependent upon laboratory capability is proposed.     

Current laboratory practices in the diagnosis and management of haemophilia: a global assessment

Haemophilia management is complicated by the extreme variability in laboratory practices. Lack of consistency or comparability in testing makes it difficult to establish diagnostic criteria or disease severity, and complicates response assessment. A global survey was conducted to document current practices. A 35‐min survey was completed by 30 laboratory scientists in each of seven countries (France, Germany, Italy, Japan, Spain, UK, USA; 210 in total); results were weighted by average country testing volume in haemophilia. Eighty‐three per cent of participants reported participation in a Quality Assurance scheme. Ninety per cent reported using clotting tests in haemophilia A and 88% in haemophilia B (55% and 53% frequent use respectively). Sixty‐eight per cent reported chromogenic assays were used in haemophilia A, with only 23% reporting frequent use, compared to only 11% reporting any use in haemophilia B. Twenty‐nine separate activated partial thromboplastin time (aPTT) reagents were reported for haemophilia A and 27 aPTT reagents were reported for haemophilia B, with one‐quarter or less obtaining reagents or kits from any single manufacturer. Fifty‐four per cent run a calibration curve with every factor VIII (FVIII) assay. The mean number of plasma dilutions varied from 2 to 4 for FVIII assays and from 1 to 3 for FIX assays. Results indicate very low consistency in materials and practices used to test for factor activity in haemophilia. A number of responses suggest that some laboratory scientists' understanding of best practices or guidelines in haemophilia could be improved. More education and broader understanding is recommended regarding assay types, assay components, test material and instrument features and capabilities.