献血者HBsAg阴性NAT可疑标本HBV感染状态确认

目的 了解天津地区无偿献血者应用PANTHER单人份核酸检测(ID-NAT)后,联检反应性,鉴别试验阴性(NAT可疑)标本HBV感染情况。方法 本中心2021年1—8月69 362份无偿献血者标本经常规检测和ID-NAT检测后,共检出HBsAg-PANTHER核酸检测联检反应性而鉴别非反应性献血者标本(以下简称NAT可疑标本)66份。采用单纯随机抽样方法选取23份应用超高速离心富集病毒后,采用超敏荧光定量PCR(qPCR)检测HBV DNA,ID-NAT复测鉴别实验,补充电化学发光法乙肝两对半检测。结果 23份NAT可疑标本中经血清学和分子生物学检测共确认HBV DNA阳性14份,HBV感染者抗-HBc阳性率为92.8%。感染者中92.8%(13/14)为隐匿性乙型肝炎病毒感染(OBI)。超敏荧光定量PCR检测共有10份标本获得病毒载量,5份可定量,病毒载量定量(11～464)IU/mL,中位数为15.4 IU/mL。结论 NAT可疑标本中仍能检出60%标本为HBV DNA阳性。抗-HBc检测能排除大多数NAT无法检测到的OBI,应提高目前NAT检测灵敏度,确保输血安全。     

献血者HBV、HCV、HIV的单人份核酸检测

目的应用Procleix ULTRIO Assay和Procleix TIGRIS System进行献血者单人份病毒核酸检测（ID-NAT）,以了解ELISA法筛查的HBV、HCV、HIV漏检率,同时对ID-NAT和汇集NAT（MP-NAT）模式进行比较。方法在进行2次ELISA法筛查的同时,应用ULTRIO试剂在TIGRIS系统上行ID-NAT检测,对有活性的标本再分别进行HBV、HCV、HIV的鉴别测定,对ID-NAT阳性标本再进行8个（MP-8-NAT）和16个（MP-16-NAT）样品的模拟混样检测。结果在10064名无偿献血者中,共检出10例ELISA法阴性、ID-NAT阳性标本,ELISA法筛查漏检率为0.99‰,该10例标本经鉴别实验确定为HBV DNA阳性;共检出28例ELISA法阳性、ID-NAT阳性标本,其中HCV6例、HBV22例。将28例ELISA法阳性、ID-NAT阳性及10例ELISA法阴性、ID-NAT阳性标本进行8个、16个样品模拟汇集,结果 MP-8-NAT、MP-16-NAT的阳性检出率分别下降为78.6%、75.0%和30.0%、20.0%。结论 2次ELISA法血清学筛查模式存在较高的HBV漏检;ID-NAT的灵敏度高于MP-NAT,对于ELISA法阴性、ID-NAT阳性标本,MP-NAT存在很高的漏检率。     

两种核酸血液筛查系统降低HBV残余风险的比较

目的评估不同原理核酸检测(NAT)血液筛查系统在降低输血传播HBV残余风险中的作用。方法对6 889人(次)无偿献血者血液标本做常规血清学检测,应用转录介导的扩增(TMA)技术(Ultrio试剂)对所有血样平行单样本定性检测HBV/HCV/HIV,对血清学无反应性标本5 165例采用PCR-荧光探针法(MPX试剂)以6人份混样模式做NAT。追踪2个NAT平台得到的反应性标本,罗氏CAP/CTM核酸定量检测系统做核酸鉴别试验,罗氏电化学发光做乙肝血清学5项检测,QPCR法测定HBV病毒载量,巢氏-PCR方法做HBV DNA基因分型,统计分析各项检测指标之间关联及差异。结果 TMA初筛检出HBV DNA单独反应性标本12例[反应率0.17%(12/6 889),鉴别试验阳性7例(占TMA初筛阳性数的58.3%)],PCR-荧光探针法拆分后检出HBV DNA单独反应性9例[0.17%(9/5 165)],2种NAT平台检测HBV DNA均为阳性4例,合计检出17例反应性标本。该2种原理的NAT检测系统对HBV DNA检测结果的一致性差(TMA vs QPCR,K0),检出率明显不同(TMA vs QPCR,P0.05)。阳性标本乙肝血清学5项检测:HBs Ag、HBe Ag均为阴性(0/16),抗-HBc阳性12例(12/16),抗-HBs阳性6例(6/16),抗-HBe阳性3例(3/16)。HBV DNA定量阳性4例,含量均5 IU/m L。献血者追踪结果:TMA检出HBV DNA单独反应性3例(3/10),鉴别试验HBV DNA阳性3例,MPX检出HBV DNA单独阳性5例(5/10),2种NAT平台检测均为阳性者3例,合计检出5例;10例追踪标本的HBs Ag、HBe Ag仍均为阴性,抗-HBc阳性8例(新转阳3例),抗-HBs阳性5例(新转阳1例),抗-HBe阳性2例(新转阳1例),HBV DNA定量阳性4例(新检出1例),含量均5 IU/m L。巢氏-PCR S区序列阳性标本做HBV基因分型:B型占66.7%(6/9),C型占33.3%(3/9)。结论 TMA与PCR-荧光定量法均能有效降低输血残余风险,但针对检出限附近低病毒载量标本均有部分漏检,血站在条件具备时可使用更高灵敏度的新试剂。     

核酸检测单反应性无偿献血者HBV感染状态分析

目的分析核酸检测(NAT)单反应性无偿献血者乙型肝炎病毒(HBV)感染状态。方法收集本实验室采用转录介导扩增技术(TMA)检出的NAT单反应性献血者标本,采用荧光定量聚合酶链反应(PCR)进行HBV DNA重复检测,并进行乙肝五项检测,分析HBV感染状态。结果225份TMA NAT单反应性标本中,检出78份(34.67%)TMA NAT鉴别检测和/或PCR检测HBV DNA阳性标本,其中76份可确定HBV感染状态,2份感染状态不能确定。76份标本中,63份(82.89%)为隐匿性HBV感染(OBI),13份(17.11%)为HBV疑似窗口期感染(pWP)。63份OBI标本中,49份(77.78%)标本HBV DNA水平小于20IU/mL。13份pWP标本中,4份(30.77%)标本HBV DNA水平小于20IU/mL。225份标本分为NAT检测值S/CO1~6组、6~10组、10~17组,HBV DNA确认阳性率分别为13.11%、13.64%、47.18%,S/CO 10~17组阳性率高于S/CO1~6组和6~10组(P0.05)。OBI标本中,NAT检测值S/CO 1~6、6~10、10~17的标本分别占12.70%(8/63)、4.76%(3/63)、82.54%(52/63)。13份pWP标本NAT检测值S/CO为10~17。结论部分NAT单反应性无偿献血者为HBV感染者,OBI所占比例远大于pWP感染者,且HBV DNA浓度水平极低,存在经输血传播HBV的风险。屏蔽NAT单反应性献血者对预防经输血传播HBV具有重要意义。     

血站核酸检测实施后献血者血液检测模式的研究

目的:探讨血站核酸检测实施后献血者血液检测的模式。方法:对无偿献血者献血后留取的血液样本先进行常规ELISA检测,对31 981阴性样本用罗氏Cobas s201仪器采用6人份混合样本(22 716例)或单人份样本(9265例)的HBV/HCV/HIV三项联合核酸检测。混合检测的具体方法为:采用常规6混合样本核酸检测,与此同时,6混合样本后用聚乙二醇沉淀法进行病毒浓缩再进行核酸检测。单份核酸检测方法为:常规单份核酸检测,在此基础上反应性样本经核酸复检阳性者,进行6倍稀释以模拟6混合样本核酸检测。对混合核酸检测出的核酸阳性样本、混合病毒浓缩核酸法检测出的阳性样本与单份核酸检测经复检核酸阳性样本的阳性率进行统计学分析;对HBV~+者进行补充血清学检测。结果:用6混合样本核酸检测﹙MP-6-NAT﹚法检测22 716份样本,9例HBV~+(0.40‰,9/22 716);同时,用6混合样本病毒浓缩核酸检测法检测同样的样本29例,显示HBV~+﹙1.28‰,29/22716﹚。用单份核酸检测﹙ID-NAT﹚法检测9 265份样本,HBV+样本12例(1.30‰,12/9 265﹚;在此基础上,对这12例HBV~+样本进行6倍稀释以模拟6混合样本核酸检测,只检出4例HBV~+样本。在血清学合格样本中,IDNAT不合格率1.30‰高于MP-6-NAT不合格率0.40‰﹙χ~2=8.11,P0.05﹚;ID-NAT不合格率1.30‰与6混合样本病毒浓缩NAT不合格率1.28‰比较差异无统计学意义﹙χ~2=0.00,P0.05﹚。41例ELISA法HBs Ag-HBV DNA+样本,经ELISA法HBsAb、HBcAb确认36例为隐匿性HBV感染者﹙OBI﹚,其中33例HBcAb~+,占OBI的91.66%。5例可能为HBV"窗口期"感染者。未发现HCV RNA、HIV RNA阳性样本。结论:为避免低病毒含量献血者漏检,在献血者血液检测模式为混合样本核酸检测时一定进行混合样本病毒浓缩处理并再进行核酸检测,否则要进行单检的检测模式,以实现更高的病毒核酸检出率;在血清学检测HBsAg基础上,应注重HBcAb血清学检测和加大献血前体检力度:对具有高危行为人群劝导不献血的模式是最简单的模式。     

血液混样核酸筛查与酶免筛查的最佳工作流程探讨

目的建立适合血液紧缺情况下,全血标本及血小板标本的常规酶免检测加混样核酸检测的最佳工作流程。方法对全血标本先行2遍酶免(EIA)检测,将检测合格的标本进行混样核酸检测(MP-6-NAT或MP-8-NAT);将EIA单试剂有反应性待复试标本双孔复试与混样核酸检测同时进行;血小板标本进行EIA及MP-NAT平行检测。结果在34 725人份全血核酸检测标本中,共34 413人份为2遍EIA检测均合格标本,检出35例NAT反应性,核酸检出率为1.0‰;312份EIA待复试标本,检出1例NAT反应性,核酸检出率为3.2‰;在3 449个血小板标本中检出2例NAT反应性,核酸检出率为0.58‰。结论全血EIA待复试标本及血小板标本的核酸阳性检出率均较低,全血待复试标本、血小板标本同时进行EIA及MP-NAT检测,可提高检测时效。     

血液核酸筛查中混样检测和单人份检测的应用分析

目的比较核酸混检模式与单检模式在献血者筛查中的检测性能。方法对本站126 359份献血者标本进行核酸检测,对初次反应性(IR)标本进行鉴别或者拆分试验。Panther联检阳性鉴别阴性的标本(NDR)再用Cobas s201系统进行单人份检测;将部分Cobas s201拆分检测阴性(NRR)标本及拆分阳性(RR)标本再用Panther进行检测(ID-NAT)。结果 Cobas s 201系统共检测标本85 128例,初次混样阳性61例(IR),经拆分后共检出阳性(RR)29例(0.34‰);Panther共检测标本41 231例,联检阳性74例(1.79‰),经鉴别后共检出HBV阳性22例,鉴别阳性(DR)率为29.73%(22/74)。28例Panther联检阳性鉴别阴性(NDR)的标本中,7例Cobas s201单样本(PP1)复检HBV DNA阳性,这7例再用s 201模拟混样(MP6)检测均为非反应性。s201拆分阳性(RR)标本28份利用Panther复检,结果阳性24例,阴性4例。2系统复检不一致的11例标本,补充血清学检测10例为抗-HBc阳性,病毒载量低。结论 Panther阳性检出率高于Cobas s201,鉴别试验阴性标本部分为OBI,有必要对未鉴别出标本进一步跟踪验证。2者检测性能各有优势,Cobas s201更适合大标本量混样NAT检测,Panther上样灵活操作简便,更适合中等标本量NAT单检。     

基于转录介导扩增的单人份核酸检测在血液筛查中的应用分析

目的探讨基于转录介导扩增(TMA)技术的单人份核酸检测(ID-NAT)在重庆地区血液筛查中的应用情况,分析其对于提高临床输血安全的作用和意义。方法对2015年1月1日-2015年12月31日采集的128 973(人)份无偿献血者标本,采用2次ELISA法检测HBs Ag、抗-HCV、抗-HIV-1/2和HIV-1 p24抗原(国产试剂为第3代,进口试剂为第4代),同时采用基于TMA原理的ID-NAT行HBV/HIV-1/HCV 3项联合检测。对ELISA非反应性而NAT反应性的标本用配套的试剂做NAT鉴别检测。结果本组中NAT反应性标本共计885例,反应性率0.69%(885/128 973),其中ELISA和NAT均为反应性的标本528例,ELISA非反应性而NAT反应性的标本为357例,NAT单反应性率0.28%(357/128 973)。对NAT单反应性的标本的鉴别检测:HBV DNA反应性114例,HIV-1RNA反应性3例,未检出HCV RNA呈反应性的标本,鉴别反应性率为32.77%(117/357)。对3例HIV-1 RNA鉴别为反应性献血者的追踪随访:均被证实为窗口期感染。结论基于TMA技术的NAT检测将HBV DNA反应性和HIV窗口期血液成功阻断,说明在血液筛查中开展NAT检测的必要性和其对于保障血液安全的重要意义。     

献血者HBsAg阴性NAT可疑结果标本乙肝感染状况的调查分析

目的了解献血者应用ULTRIO PLUS核酸检测(NAT)后,初始反应性,鉴别实验阴性(NAT可疑结果)标本HBV DNA感染情况,分析其血清学和分子生物学特征,提高输血安全性。方法本中心2017年1—12月的97 577人(份)无偿献血者标本经常规和NAT检测后,收集HBsAg ELISA(-)/HBV DNA可疑标本,进行乙肝两对半检测与HBV DNA大容量提取,采用巢氏PCR方法扩增BCP/PC和S区基因序列,并对所得序列做基因型分析,同时采用实时荧光定量PCR检测(qPCR)和分析。结果 97 577(人)份献血者标本,通过ELISA和NAT初筛检出205(0.21%)份NAT可疑标本,经血清学、巢氏PCR和qPCR检测,93/205(45.4%)确证HBV DNA阳性, 92/93(98.9%)为隐匿性乙肝感染(OBI)标本。病毒定量范围(5—65.2)IU/mL,中位数为8.1 IU/mL。在可分型的35例标本中,HBV基因型B型18例(51.4%)、C型17例(48.6%)。结论 NAT可疑标本中仍能检出近半数标本为HBV DNA阳性,应提高目前NAT检测灵敏度,确保输血安全。     

病毒核酸检测在献血者血液筛查中的应用

目的　建立献血者血液混合核酸检测方法 ,调查北京现有检测体系下血液的残余风险度 ,评估核酸检测 (NAT)的必要性和可行性。方法　用世界卫生组织标准品对国产丙型肝炎病毒(HCV)和人免疫缺陷病毒 (HIV)荧光 聚合酶链反应核酸扩增检测试剂进行灵敏度、重复性和精密度试验 ;对 2 0 0 2年 2～ 10月 34373份常规血清学检测 (ALT、HBsAg、抗 HCV、抗 HIV、梅毒抗体 )合格的献血者血样进行HCVRNA和HIV 1RNA核酸扩增分析。采取 2 4人份混合血样测定 ,超离心浓缩病毒 ,Roche核酸提取柱提取病毒核酸。结果　扩增系统能 10 0 %检出 5 0IU/mlHCV及 5 0IU/mlHIV 1标准品核酸 (n =16 ) ;常规血清学检测合格的献血者血液中 ,没有检出HCV或HIVNAT阳性。结论　该核酸检测体系适用于献血者血液病毒筛查 ;北京市血液的病毒安全性已有相当高的保障。为更准确地评估NAT检测项目的可行性和必要性 ,检测标本量尚待增加。     

Hepatitis B virus nucleic acid testing in Chinese blood donors with normal and elevated alanine aminotransferase

BACKGROUND: Nucleic acid testing (NAT) is currently not a routine donor test in China. The aim of this study was to evaluate the current residual risk of hepatitis B virus (HBV) transmission and the value of ALT testing in preventing HBV infection. STUDY DESIGN AND METHODS: From January 2008 to September 2009, a total of 5521 qualified donations by routine screening and 5034 deferred donations due to elevated ALT alone were collected from five blood centers. Samples were tested for HBV DNA by triplex individual‐donation (ID)‐NAT (ULTRIO assay, on the TIGRIS system, Novartis Diagnostics). HBV NAT–reactive samples were further analyzed by HBV serology, alternative NAT, and viral load and were diluted to simulate if they could be detected in a minipool‐NAT. RESULTS: There was no significant difference in the HBV NAT–yield rate between the qualified donations group (5/5521) and the deferred donations group (4/5034). Of these nine potential HBV‐yield cases, one donor (11%) was a possible HBV window‐period donor, one (11%) was a chronic HBV carrier, and seven (78%) had probable or confirmed occult HBV infections. Of seven potential HBV‐yield cases quantified, the viral loads were less than or equal to 70.0 IU/mL. Minipool testing (minipools of 4, 8, and 16 donations) would miss 43% to 79% of the nine HBV‐yield donations. CONCLUSIONS: Based on our findings in qualified donations, we estimate that the nationwide implementation of ID‐NAT testing for HBV DNA in China would detect an additional 9964 viremic donations per year. ALT testing seems to have no significant value in preventing transfusion‐transmitted HBV infection. ID‐NAT versus simulated minipool‐NAT using the ULTRIO test demonstrates the benefit to implement a more sensitive NAT strategy in regions of high HBV endemicity.     

Cost-effectiveness of additional hepatitis B virus nucleic acid testing of individual donations or minipools of six donations in the Netherlands

BACKGROUND: To further reduce the risk of hepatitis B virus (HBV) transmission by blood transfusion, nucleic acid testing (NAT) can be employed. The aim of this study is to estimate the incremental cost-effectiveness ratio (ICER) in the Netherlands of employing a triplex NAT assay aimed at HBV nucleic acid detection in individual donations (ID-NAT) or in minipools of 6 donations (MP-6-NAT), compared to a triplex NAT assay in minipools of 24 donations (MP-24-NAT).
STUDY DESIGN AND METHODS: A mathematical model was made of the whole transfusion chain from donors to recipients of blood in the Netherlands. The annual number of avoided HBV transmissions was estimated with the window-period incidence model. The natural history of a HBV infection in recipients is described by a Markov model.
RESULTS: The ICER of adding HBV MP-6-NAT or HBV ID-NAT in the Netherlands is €303,218 (95% confidence interval [CI], €233,001-€408,388) and €518,995 (95% CI, €399,359-€699,120) per quality-adjusted life-year, respectively. The ICER strongly correlates with the age of transfusion recipients.
CONCLUSION: The cost-effectiveness of additional HBV NAT is limited by the limited loss of life caused by HBV transmission. Despite a higher effectiveness, HBV ID-NAT is less cost-effective than MP-6-NAT due to higher costs. A future equivalent participation of immigrants from HBV-endemic countries in the donor base renders HBV NAT only slightly more cost-effective.     

上海地区无偿献血者乙肝病毒核酸检测分析

目的了解无偿献血者乙肝病毒核酸筛查(NAT)阳性人群特点,为血液安全策略提供参考。方法无偿献血者血液经Murex和科华HBsAg ELISA试剂检测,结果为阴性的血液使用cobas TaqScreen MPX试剂进行HBV DNA,HCV RNA,HIV RNA 3项联合核酸检测。对于MPX反应性标本,使用COBAS AmpliPrep/TaqMan进行核酸鉴别试验,同时使用罗氏ECL电化学发光检测系统进行乙肝补充血清学试验。结果 2011年11月1日～2012年1月31日3个月共有献血者86 375人(次),其中有63 351人(次)为初次献血者,HBsAg反应性为1.04%,23 024人(次)为重复献血者,HBsAg反应性为0.46%,两者差异有统计学意义(χ2=63.63,P0.05)。84 990份HBsAg、抗-HCV、抗-HIV1/2阴性血液进行MPX核酸检测,共发现52例(0.060%)HBV DNA阳性,均为低拷贝,含量为(20～200)IU/ml间,其中32例(0.051%)来自初次献血者,20例(0.087%)来自重复献血者,两者比例差异无统计学意义(χ2=3.65,P0.05),没有发现HCV RNA与HIV RNA阳性。结论重复献血者HBsAg反应性比率低于初次献血者;HBsAg阴性献血者HBV DNA阳性率为0.060%,重复献血者HBV DNA阳性率与初次献血者比较,两者差异无统计学意义;开展HBV核酸检测能够进一步保障血液安全。     

河南省18家血站2017~2019年HIV/HBV/HCV核酸单独阳性结果趋势性分析

目的分析河南省不同地区HIV/HBV/HCV核酸阳性献血者的流行情况,为疾病防控及建立全省统一的核酸检测质量控制标准提供依据。方法统计河南省18家血站2017~2019年检出的核酸单阳性标本的数量及其阳性率,分析其变化趋势;并根据核酸检测混检拆分率,分析各实验室以及各检测系统的核酸检测质量情况。结果河南省18家血站2017~2019年共计检测标本3 501 251例,核酸单独阳性标本中HBV 2 606例(流行率74/10万)、HCV 21例(流行率0.63/10万)、HIV 34例(流行率1.00/10万)。HBV核酸单独阳性标本的阳性率全省总体数据呈上升趋势,HIV和HCV核酸单独阳性标本的阳性率3年无明显差异。核酸检测系统Ⅰ、Ⅱ、Ⅳ、Ⅴ为混检系统,混检阳性5 595例,拆分阳性2 661例,拆分阳性率为47.56%,其中核酸检测系统Ⅰ、Ⅱ、Ⅳ、Ⅴ的混检拆分率分别为39.63%~47.95%、40.43%~54.36%、51.61%、70.00%~45.45%。核酸检测混检拆分呈上升趋势的为B、D、E、F、I、K、L和Q 8家实验室,呈下降趋势的为A、C 2家实验室。核酸检测系统Ⅲ为单人份核酸检测系统,只有C实验室使用,其联检阳性率为0.19%(282/145 474),鉴别阳性率为46.45%(131/282)。结论河南省血站核酸检测单独阳性标本以HBV为主,且多呈逐年上升趋势。不同实验室核酸检测质量管理存在差异,提示应加强实验室质量管理。     

Sensitivity of hepatitis B virus DNA transcription-mediated amplification testing in hepatitis B surface antigen-positive blood donations

BACKGROUND: The objective was to evaluate the performance of nucleic acid testing (NAT) in the detection of hepatitis B virus (HBV) infection in hepatitis B surface antigen (HBsAg)-positive blood donations. STUDY DESIGN AND METHODS: A total of 253 HBsAg- and anti-hepatitis B core antigen (HBc)-positive samples (50 hepatitis B e antigen [HBeAg]-positive and 203 anti-HBe-positive) from blood donations collected in France were studied. The samples were investigated with a blood screening assay (Procleix Ultrio, Chiron/Gen-Probe) in minipool (MP; x8) and in individual-donation (ID) testing. All nonreactive samples were retested once, and nonreactive MP samples were assayed for viral load (VL). RESULTS: All 50 HBeAg-positive samples were reactive in MP-NAT and ID-NAT. Of the 203 anti-HBe-positive donations, 80.3 percent were MP- and ID-reactive, 17.2 percent were MP-nonreactive and ID-reactive, and 2.5 percent were nonreactive in ID-NAT. Overall the sensitivity of ID-NAT was 98 percent versus 84 percent for MP-NAT. After retesting, 16 of the 35 MP-nonreactive and/or ID-reactive donations became MP-reactive and 2 of the ID-nonreactive donations became NAT-reactive. The capacity of Procleix Ultrio to detect HBV DNA was not related to HBsAg subtype, but correlated with the VL: the mean VL in the group of MP-nonreactive samples was 1,420 copies per mL vs. 17,000 copies per mL in the group of 40 MP-reactive samples. CONCLUSION: These results demonstrate that HBV-NAT in ID format is far more effective in detecting viremia in chronic HBsAg carriers than in MP-NAT. The sensitivity of the NAT assay needs to be improved to be considered for replacing the current HBsAg assays, especially when anti-HBc testing is not performed.     

West Nile virus testing experience in 2007: evaluation of different criteria for triggering individual-donation nucleic acid testing

BACKGROUND: In 2007, clients served by Blood Systems Laboratories used variable approaches for triggering West Nile virus (WNV) RNA individual-donation (ID) nucleic acid testing (NAT). These included two minipool (MP) NAT–reactive donations and a greater than 1:1000 rate in a 7-day interval (primary trigger), criteria based on one MP-NAT–reactive donation when there was WNV activity in overlapping and/or adjacent geographic areas (neighbor trigger), or zero MP-NAT–reactive donation (self-trigger).
STUDY DESIGN AND METHODS: The Procleix WNV assay was used in either a 16-sample MP or an ID format. NAT-repeat reactivity or anti-immunoglobulin M (IgM) positivity defined true positives (TPs). TPs that were negative on 1:16 dilution testing were considered ID-NAT yield cases.
RESULTS: WNV NAT performed on 1,217,929 donations identified 162 TPs; 87 were detected by MP (rate of 0.008%) and 75 by ID (rate of 0.10%; p < 0.0001). There were 34 ID-NAT yield cases, including 4 IgM/immunoglobulin G (IgG)-negative and 9 IgM-positive/IgG-negative donations. Rates of yield cases by primary, neighbor, and self-triggering were 0.077, 0.052, and 0.004% (p = 0.0003). None of 11 ID-NAT yield cases detected by the neighbor trigger would have been detected if the primary trigger had been used.
CONCLUSIONS: Primary triggering criteria identified 21 viremic donations that would have been missed by MP testing; however, 11 other low-level viremic donations required more stringent criteria (e.g., neighbor trigger) for detection. It is reasonable to adopt more stringent ID-NAT triggers, including elimination of the rate criterion and triggering on one NAT-reactive donation for regions adjacent to centers which have already triggered.     

Two HBV DNA+/HBsAg− blood donors identified by HBV NAT in Shenzhen, China

Background

In order to further improve blood safety, mini-pool (MP) nucleic acid testing (NAT) was implemented to screen samples negative for hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (anti-HCV), anti-human immunodeficiency virus (anti-HIV), syphilis (anti-Treponemal antibody) and with normal ALT.

Study design and methods

From August 2006 to February 2008, 41,301 donations were screened using commercial HIV/HCV RNA and HBV DNA Real-Time PCR NAT assays in pools of 8. Reactive pools were re-tested as individual samples using the appropriate screening test and confirmed using an alternate commercial NAT assay. Donors reactive on both NAT assays were considered ‘confirmed’ positive for the virus concerned and recalled for additional follow-up testing and counseling.

Results

Of the 41,301 samples screened, no HIV or HCV RNA-positive/seronegative donations were detected but two HBV DNA positive/HBsAg negative blood donors (Donors 1 and 2) were identified. Their respective hepatitis immunological markers were: Donor 1 - anti-HBc positive/anti-HBe positive/HBeAg negative/ALT normal and HBV DNA viral load of 112 IU/ml; Donor 2 - anti-HBc positive/anti-HBe negative/HBeAg negative/ALT normal and HBV DNA viral load 2750 IU/ml.

Conclusions

MP NAT identified two HBsAg negative donors with presumed occult infection but no HIV or HCV seronegative/NAT positive (yield) donors. The HBV yield rate of 1 in 20,650 (95%CI - 1 in 5663 to 1 in 75,303) is comparatively high, exceeds the predicted rate based on previous modeling for the population and demonstrates the incremental blood safety value of NAT in countries where HBV is highly epidemic. The low viral load of the two yield samples underscores the importance of optimizing the sensitivity of the HBV NAT assay selected for screening.     

NAT for HBV and anti-HBc testing increase blood safety

BACKGROUND: Routine HBV PCR screening of blood donations to our institutes was introduced in January 1997 to complete the NAT screening program for transfusion-relevant viruses. Testing was successively extended to customer transfusion services with a total of 1,300,000 samples tested per year. STUDY DESIGN AND METHODS: Minipools of 96 blood donation samples were formed by automatic pipettors. HBsAg-reactive samples were included. HBV particles were enriched from the minipools by centrifugation. Conventional and in-house TaqMan PCRs were successively applied for HBV amplification. Sensitivity reached 1000 genome equivalents per mL for each individual donation. Confirmatory single-sample and single-sample enrichment PCRs were established with sensitivities of 300 and 5 to 10 genome equivalents per mL, respectively. RESULTS: After screening of 3.6 million donor samples, 6 HBV PCR-positive, HBsAg-negative donations were identified. Two samples were from infected donors who had not seroconverted and four were from chronic anti-HBc-positive low-level HBV carriers. Retesting by single-sample PCR of 432 samples confirmed positive for HBsAg identified 37 donations that were negative in minipool PCR. Donor-directed look-back procedures indicated that no infected donor who had not yet seroconverted was missed by minipool PCR. However, recipient-directed look-back procedures revealed two anti-HBc-positive recipients of HBsAg-negative minipool PCR-negative, anti-HBc-positive and single-sample PCR-positive blood components. After testing randomly selected 729 HBsAg-negative minipool PCR-negative, anti-HBc-positive donors by single-sample enrichment PCR, 7 were identified with < or = 10 HBV particles per mL of donor plasma. CONCLUSION: Minipool PCR testing after virus enrichment was sensitive enough to identify HBsAg-negative donors who had seroconverterd and HBsAg-negative, anti-HBc-positive chronic HBV carriers. HBV NAT in conjunction with anti-HBc screening would reduce the residual risk of transfusion-transmitted HBV infection.     

Serological characterization of occult hepatitis B virus infection among blood donors in India

IntroductionDiscovery of hepatitis B infections characterized by the presence of viral genome without detectable HBsAg (Occult Hepatitis; OBI) has initiated a considerable amount of research in this regard. Our study is a serological and molecular characterization of OBI among the donors who donated at our blood bank during the study period.Material and MethodDuring the study period HBsAg ELISA non reactive ID-NAT reactive donors samples were screened for presence of antibody against HBc, HBs and HBe. Molecular analysis of these NAT yield samples was undertaken for detection of the viral load and genotyping.ResultWe studied 28,134 HBsAg ELISA non reactive donor samples. On testing them with ID-NAT, HBV DNA was detected in 25 samples. Eighteen samples out of these 25 NAT yield were further worked up. The 66.6% of the NAT yield samples (12 out of 18) were reactive for antibody against HBc. The 25% (3 out of 12) of these NAT yield samples having antibody against core antigen also had antibody against HBs. The 27.7% (5 out of 18) of NAT yield detected by ID-NAT did not have any detectable serological marker in blood. Four out of 12 core antibody positive NAT yield samples had genotype A HBV infection.ConclusionAs per our study molecular detection of HBV DNA by ID-NAT, we were able to analyze 18 HBV NAT yield cases among 28,134 HBsAg ELISA non reactive donors. Out of 18, 12 donors were OBI whereas the rest (6) were in window period (WP yield) of HBV infection. One out of every 3.6 NAT yield detected by ID-NAT was non reactive for all serological markers.