Hepatitis B viral load in dried blood spots: A validation study in Zambia

BackgroundAccess to hepatitis B viral load (VL) testing is poor in sub-Saharan Africa (SSA) due to economic and logistical reasons.ObjectivesTo demonstrate the feasibility of testing dried blood spots (DBS) for hepatitis B virus (HBV) VL in a laboratory in Lusaka, Zambia, and to compare HBV VLs between DBS and plasma samples.Study designPaired plasma and DBS samples from HIV-HBV co-infected Zambian adults were analyzed for HBV VL using the COBAS AmpliPrep/COBAS TaqMan HBV test (Version 2.0) and for HBV genotype by direct sequencing. We used Bland-Altman analysis to compare VLs between sample types and by genotype. Logistic regression analysis was conducted to assess the probability of an undetectable DBS result by plasma VL.ResultsAmong 68 participants, median age was 34 years, 61.8% were men, and median plasma HBV VL was 3.98 log IU/ml (interquartile range, 2.04–5.95). Among sequenced viruses, 28 were genotype A1 and 27 were genotype E. Bland–Altman plots suggested strong agreement between DBS and plasma VLs. DBS VLs were on average 1.59 log IU/ml lower than plasma with 95% limits of agreement of −2.40 to −0.83 log IU/ml. At a plasma VL ≥2,000 IU/ml, the probability of an undetectable DBS result was 1.8% (95% CI: 0.5–6.6). At plasma VL ≥20,000 IU/ml this probability reduced to 0.2% (95% CI: 0.03–1.7).ConclusionsIn a Zambian laboratory, we observed strong agreement between DBS and plasma VLs and high sensitivity in DBS at plasma VL ≥2,000 IU/ml. As HBV treatment expands, DBS could increase access to HBV VL testing and care in SSA settings.     

Comparison of the performance of enzyme immunoassays for hepatitis B and C detection in dried blood spot

Dried blood spots (DBSs) could be an alternative to serum for hepatitis B virus (HBV) and hepatitis C virus (HCV) diagnosis. This study aims to evaluate two enzyme immunoassays (EIAs) for HBsAg and anti-HCV detection using DBS. Serum was tested using commercial EIA. DBS was tested using optimized EIA developed for serum and commercial EIA developed for DBS (Imunoscreen). Concordances between DBS and serum samples for both markers and EIAs were higher than 97%. Both EIAs demonstrated good performance for HBsAg and anti-HCV detection using DBS, and these methods could be used unchangeably increasing the access for HBV and HCV diagnosis.     

干血斑滤纸片中人免疫缺陷病毒1型前病毒基因的检测

目的建立套式引物聚合酶链反应（ＰＣＲ），用于检测滤纸干血斑中的人免疫缺陷病毒１型（ＨＩＶ１）前病毒ｐｏｌ基因ＤＮＡ片段。方法采集ＨＩＶ１感染者的全血约５０μｌ滴在经ＥＤＴＡ－蛋白酶Ｋ预处理并干燥的滤纸片上，室温下干燥，将滤纸片密封于塑料袋中，在室温及４℃下保存１～６４周后，分别将滤纸片置０５ｍｌ试管中直接进行ＨＩＶ１前病毒ｐｏｌ基因的外侧引物ＰＣＲ检测，然后进行内侧引物的ＰＣＲ检测。结果经ＥＤＴＡ－蛋白酶Ｋ预处理的滤纸片在４℃下保存４０周、在室温下保存２４周仍可检出ＨＩＶ１前病毒目的基因。根据ＰＣＲ产物的琼脂糖凝胶电泳溴化乙锭染色带形并参比实验设立的标准对照可直接判断结果。结论该方法具有快速、特异、敏感的特点，敏感性可以达到检出１０个靶ＤＮＡ分子。样品采集后可通过邮件传递至中心实验室，特别适合于ＨＩＶ１感染的确证及筛检     

Comparison of HIV-1 detection in plasma specimens and dried blood spots using the Roche COBAS Ampliscreen HIV-1 test in Kisumu, Kenya

The World Health Organization recommends screening donor blood for HIV in centralized laboratories. This recommendation contributes to quality, but presents specimen transport challenges for resource-limited settings which may be relieved by using dried blood spots (DBS). In sub-Saharan Africa, most countries screen donor blood with serologic assays only. Interest in window period reduction has led blood services to consider adding HIV nucleic acid testing (NAT). The U.S. Food and Drug Administration (FDA) mandates that HIV-1 NAT blood screening assays have a 95% detection limit at or below 100 copies/ml and 5000 copies/ml for pooled and individual donations, respectively. The Roche COBAS Ampliscreen HIV-1 test, version 1.5, used for screening whole blood or components for transfusion, has not been tested with DBS. We compared COBAS Ampliscreen HIV-1 RNA detection limits in DBS and plasma. An AIDS Clinical Trials Group, Viral Quality Assurance laboratory HIV-1 standard with a known viral load was used to create paired plasma and DBS standard nine member dilution series. Each was tested in 24 replicates with the COBAS Ampliscreen. A probit analysis was conducted to calculate 95% detection limits for plasma and DBS, which were 23.8 copies/ml (95% CI 15.1-51.0) for plasma and 106.7 copies/ml (95% CI 73.8-207.9) for DBS. The COBAS Ampliscreen detection threshold with DBS suggests acceptability for individual donations, but optimization may be required for pooled specimens.     

The use of dried blood spots on filter paper for the diagnosis of HIV-1 in infants born to HIV seropositive women

Polymerase chain reaction (PCR) is the most sensitive test to diagnose HIV-1 infection among infants born to HIV seropositive mothers. The purpose of this study was to evaluate the use of dried blood spot (DBS) specimens for PCR and to compare it with whole-blood stored in tubes for HIV-1 DNA PCR. Five hundred and seventy-seven whole-blood infant samples were tested using HIV-1 qualitative in-house nested DNA PCR. Three hundred and fifty-nine samples were from infants at 48 hours of birth and 218 samples at second month. All positive samples tested from whole-blood and every fifth negative sample were coated onto filter paper. DNA was extracted from the filter paper and was amplified using in-house nested PCR. Among the whole-blood samples tested using HIV-1 DNA PCR, 19 of 359 (5.29%) samples were HIV-1 positive and 340 (94.7%) were negative at 48 hours of birth. At second month, 19 (8.7%) of the 218 samples were positive and 199 (91.2%) were negative. Using dried filter paper, 18 samples (95%) tested positive from 19 positive samples (using whole-blood) and 1 tested negative at 48 hours of birth. The 68 negative samples tested using whole-blood were also negative in the DBS test (sensitivity 95% and specificity 100%). At second month, 19 were positive and 40 samples (every fifth sample of 199) were negative (sensitivity and specificity, 100%). PCR performed using DNA extracted from filter paper permits the diagnosis of HIV-1 infection among infants born to HIV-1 seropositive mothers. This assay is simple, rapid, sensitive and specific and can be used in resource limited settings.     

Active tracking of rejected dried blood samples in a large program in Nigeria

AIM: To study the impact of rejection at different levels of health care by retrospectively reviewing records of dried blood spot samples received at the molecular laboratory for human immunodeficiency virus (HIV) early infant diagnosis (EID) between January 2008 and December 2012. METHODS: The specimen rejection rate, reasons for rejection and the impact of rejection at different levels of health care was examined. The extracted data were cleaned and checked for consistency and then de-duplicated using the unique patient and clinic identifiers. The cleaned data were ciphered and exported to SPSS version 19 (SPSS 2010 IBM Corp, New York, United States) for statistical analyses. RESULTS: Sample rejection rate of 2.4% (n = 786/32552) and repeat rate of 8.8% (n = 69/786) were established. The mean age of infants presenting for first HIV molecular test among accepted valid samples was 17.83 wk (95%CI: 17.65-18.01) vs 20.30 wk (95%CI: 16.53-24.06) for repeated samples. HIV infection rate was 9.8% vs 15.9% for accepted and repeated samples. Compared to tertiary healthcare clinics, secondary and primary clinics had two-fold and three-fold higher likelihood of sample rejection, respectively (P < 0.05). We observed a significant increase in sample rejection rate with increasing number of EID clinics (r = 0.893, P = 0.041). The major reasons for rejection were improper sample collection (26.3%), improper labeling (16.4%) and insufficient blood (14.8%). CONCLUSION: Programs should monitor pre-analytical variables and incorporate continuous quality improvement interventions to reduce errors associated with sample rejection and improve patient retention.     

HBsAg ELISA试剂盒筛检结果的评估

目的 评估部分国产与进口HBsAg ELISA试剂盒筛查血源的价值.方法 选用部分国产和进口HBsAg ELISA试剂,对中国生物制品检定所120份HBsAg临床科研组合血清样本及随机抽取400份东莞市无偿献血者血清标本为验证样本进行同步平行检测,以中国生物制品检定所组合血清及献血者HBsAg阳性并经中和试验证实者为金标准.结果采用四格表法计算两者对等指标并进行评价.结果 国产HBsAg ELISA试剂和进口HBsAg ELISA试剂的灵敏度分别为85.71%（72/84）和100%（84/84）;特异性分别为100%（436/436）和96.55%（421/436）;尤登指数分别为0.86、0.97;两种试剂重复合格率均为100%.结论 试剂的灵敏度以进口HBsAg ELISA试剂较好,但特异性比国产试剂差,两种试剂的重复性均好,两种试剂联合筛检献血者血样标本可提高临床输血的安全性.     

Liver histology in patients with HBsAg negative anti-HBc and anti-HCV positive chronic hepatitis

The liver histology of 68 consecutive anti-HCV/HCV-RNA positive chronic hepatitis patients who were HBsAg/anti-HBs negative, anti-HBc positive (Case bC group) was compared with that of 68 anti-HCV/HCV-RNA positive chronic hepatitis patients who were HBsAg/anti-HBc negative (control C group). The patients were pair-matched by age (+/-5 years), sex, and risk factors for the acquisition of parenteral infection. Case bC group showed a significantly higher mean fibrosis score (2.3 +/- 1.1) than control C group (1.5 +/- 1.1, P <0.001) and more histological evidence of cirrhosis (22% vs. 7.3%, P <0.05). In addition, the patients in Case bC group showed more severe inflammation of the portal tracts (3.5 +/- 0.8 vs. 3.0 +/- 1.1, P <0.005) and there was a higher prevalence of patients with rhomboid-shaped hepatocytes (26.4% vs. 2.7%, P <0.005), acidophilic bodies (33.8% vs. 1.4%, P <0.0001), sinusoidal inflammation (29.4% vs. 10.3%, P <0.01), lymphoid follicles in the portal tracts (72% vs. 44.1%, P <0.05), Kupffer cell proliferation (29.4% vs. 11.8%, P <0.05), bile duct damage (44.1% vs. 10.3%, P <0.0001), and ductular proliferation (30.9% vs. 2.7%, P <0.001) than in control C group. No difference in these histological features was observed between HBV-DNA negative and positive patients in Case bC group. The data suggest that anti-HBc positive patients with HCV chronic infection have a significantly higher degree of liver fibrosis, and that hepatocellular apoptosis, bile duct damage, and ductular proliferation correlate with the presence of this antibody in the serum.     

Effects of blood sample handling procedures on measurable inflammatory markers in plasma, serum and dried blood spot samples

The interests in monitoring inflammation by immunoassay determination of blood inflammatory markers call for information on the stability of these markers in relation to the handling of blood samples. The increasing use of stored biobank samples for such ventures that may have been collected and stored for other purposes, justifies the study hereof. Blood samples were stored for 0, 4, 24, and 48 h at 4 degrees C, room temperature (RT), and at 35 degrees C, respectively, before they were separated into serum or plasma and frozen. Dried blood spot samples (DBSS) were stored for 0, 1, 2, 3, 7, and 30 days at the same temperatures. 27 inflammatory markers in serum and plasma and 25 markers in DBSS were measured by a previously validated multiplex sandwich immunoassay using Luminex xMAP technology. The measurable concentrations of several cytokines in serum and plasma were significantly increased when blood samples were stored for a period of time before the centrifugation, for certain cytokines more than 1000 fold compared to serum and plasma isolated and frozen immediately after venepuncture. The concentrations in serum generally increased more than in plasma. The measurable concentrations of inflammatory markers also changed in DBSS stored under various conditions compared to controls frozen immediately after preparation, but to a much lesser degree than in plasma or serum. The study demonstrates that trustworthy measurement of several inflammatory markers relies on handling of whole blood samples at low temperatures and rapid isolation of plasma and serum. Effects of different handling procedures for all markers studied are given. DBSS proved to be a robust and convenient way to handle samples for immunoassay analysis of inflammatory markers in whole blood.     

抗HBc IgM阳性慢性乙型肝炎临床特性、病毒学和血清学研究

目的探讨抗HBcAg IgM阳性慢性阳性肝炎患者的临床特性及其与HBV病毒学和血清学的关系。方法收集河北省张家口市传染病医院和北京地坛医院2004—2006年经Abbott EIA检测试剂证实的所有抗HBcAg IgM阳性和同期随机抽样的抗HBcAg IgM阴性患者的临床资料,包括生化指标、血清HBV DNA载量和血清学指标,分析抗HBcAg IgM阳性和阴性患者的疾病程度和临床转归之间的差异及抗HBcAg IgM状态与HBV DNA载量和HBeAg状态的关系。结果收集了200例慢性乙型肝炎患者,其中抗HBc IgM阳性70例,阴性130例,轻、中和重度肝脏疾病患者分别为71、83、46例。抗HBc IgM阳性患者的年龄和发病年数高于抗HBc IgM阴性患者,抗HBc IgM阳性的轻度肝脏疾病患者百分比为45.71%,中重度患者为54.29%,低于抗HBc IgM阴性患者(30.00%和70.00%),差异有统计学意义(χ2=4.907,P=0.027)。抗HBc IgM阳性患者和阴性患者的HBV DNA载量,血清HBeAg/抗HBe状态、住院天数和转归差异无统计学意义。结论慢性乙型肝炎患者抗HBcAg IgM的状态与肝脏疾病的程度相关,但与HBV DNA载量和HBeAg/抗HBe状态无相关性。     

Evaluation of the Murex HIV Ag/Ab Combination assay when used with dried blood spots

This study evaluated the ability of the Murex HIV Ag/Ab Combination assay to detect human immunodeficiency virus (HIV) antibodies in 12 617 dried blood spots (DBSs) on filter paper. The assay had an overall sensitivity of 99.6% and a specificity of 99.9%. In view of its ability to detect p24 antigen and both HIV-1 and HIV-2 antibodies in samples collected in the form of DBSs, the Murex Ag/Ab Combination assay is suitable for use as a standard screening assay for seroprevalence studies, as well as for routine diagnostic use in clinical laboratories.     

Evaluation of a modified commercial assay in detecting antibody to hepatitis C virus in oral fluids and dried blood spots

Oral fluid testing is an effective alternative to serum antibody testing for surveillance of human immunodeficiency virus (HIV) and hepatitis B infections, and is being extended to hepatitis C infections. The objective of this study was to determine and compare the sensitivity and specificity of a modified commercial assay for the detection of antibody to hepatitis C virus (anti-HCV) in oral fluids collected by two different oral fluid collection devices (the Epitope OraSure trade mark and Sarstedt Salivette ) and in dried fingerprick blood spots. In this study, 253 anti-HCV seropositive patients and 394 blood donors (all anti-HCV negative) were recruited between August 2000 and January 2001. Each participant provided oral fluid specimens by OraSure and Salivette, and at least one dried blood spot. Serum specimens were collected from the patients whenever possible. For those injecting drug users who did not provide a serum specimen, HCV status was established on the basis of previous testing. All the nonserum samples were tested for the presence of anti-HCV, using a modified Ortho HCV 3.0 SAVe enzyme-linked immunosorbent assay (ELISA) protocol. The recommended preliminary cutoffs for the modified ELISA were suboptimal. Further, the sensitivity, specificity, and positive and negative predictive values could be improved by varying the cutoff and taking into account the likely prevalence of HCV in the population under investigation. For instance, given a population with a 50% prevalence of anti-HCV, the optimal sensitivities of the modified assay on OraSure, Salivette, and dried blood spots were 92%, 83%, and virtually 100%, respectively, in contrast to 83%, 59%, and 99% using the preliminary cutoffs. The respective optimal specificities were 99%, 93%, and 100%. In conclusion, oral fluids collected by the OraSure device provide an extremely useful method to conduct public health surveillance of not only HIV, but also hepatitis C, among injecting drug users. In addition, dried blood spot specimens may be useful for surveillance and could be employed as a first line diagnostic specimen.     

Dried blood spot samples: Optimization of commercial EIAs for hepatitis C antibody detection and stability under different storage conditions

This study was undertaken to optimize and compare the efficiency of two commercial EIAs for anti‐HCV detection (HCV Ab Radim, Pomezzia, Italy and ETI‐AB‐HCVK‐4 DiaSorin, Vercelli, Italy), in dried blood spot (DBS) samples. The long‐term stability of anti‐HCV on DBS samples stored at three environmental conditions was also evaluated at: 2–8°C, 20–25°C, and ?20°C. Paired DBS and serum samples were obtained from individuals with or without anti‐HCV. The type of elution buffer, sample and conjugate volume, sample incubation time and cut‐off values were evaluated. For both EIAs, a larger sample volume was used, and the cut‐off value determined by the manufacturer was employed for Radim EIA; however, ROC curve analysis was used for the DiaSorin EIA. The sensitivity and specificity of Radim EIA on DBS were 97.5% and 99.5%, respectively, and of DiaSorin EIA were 88.9% and 98.9%, respectively. Accurate results were obtained for a period of 117 days using DBS samples stored at all storage conditions, but storage at ?20°C resulted in the lowest variation among the absorbance values. Both EIAs demonstrated the same limit of detection (until dilution of 1:10⁴ with estimated viral load of 3.1 × 10^?1 UI/ml), but the Radim EIA was associated with the best performance because a low coefficient of variation was observed in the repetition and reproducibility studies. In conclusion, commercial EIAs can be optimized for anti‐HCV detection in DBS samples that are extremely stable at different conditions for more than 100 days. J. Med. Virol. 84:1600–1607, 2012. © 2012 Wiley Periodicals, Inc.     

The use of real-time PCR to detect hepatitis C virus RNA in dried blood spots from Brazilian patients infected chronically

Collecting and transporting samples for RNA analysis can be challenging, especially in situations where financial resources are limited. In this study, a quantitative real-time PCR (qPCR) for the analysis of HCV RNA was developed and adapted for use with dried blood spot (DBS) samples. A qPCR for HCV 5′NCR, an internal control and a calibration curve were developed, and the sensitivity, specificity and dynamic range of amplification were evaluated using a panel of viruses. Plasma and DBS samples from 100 patients who had completed four weeks of Peginterferon alfa-2b + Ribavirin treatment were collected (DBS on SS903 collection cards and transported at room temperature). After 24 weeks of treatment, samples were collected from 68 of these patients. Of the 168 samples, 2 yielded false-negative results, and 4 yielded false-positive results (sensitivity was 98%, specificity was 94.3%, positive predictive value was 96.1%, and negative predictive value was 96.9%). Additionally, 2039 DBS samples from 1114 patients currently undergoing treatment for a chronic HCV infection in a clinical trial were tested. Only 10 samples out of the 2039 yielded invalid results warranting re-collection of DBS. The detection of HCV RNA in DBS can be a cost-effective strategy for HCV treatment monitoring, especially in settings where resources are limited.     

Combining rapid diagnostic tests and dried blood spot assays for point-of-care testing of human immunodeficiency virus,hepatitis B and hepatitis C infections in Burkina Faso,West Africa

People screened for human immunodeficiency virus (HIV) using rapid diagnostic tests (RDTs) in Africa remain generally unaware of their status for hepatitis B (HBV) and hepatitis C (HCV) infections. We evaluated atwo-step screening strategy in Burkina Faso, using both HIV RDTs and Dried Blood Spot (DBS) assays to confirm an HIV-positive test, and to test for HBV and HCV infections. HIV counselling and point-of-care testing were performed at a voluntary counselling and testing centre with HBV, HCV status and HIV confirmation using DBS specimens, being assessed at a central laboratory. Serological testing on plasma was used as the reference standard assay to control for the performance of DBS assays. Nineteen out of 218 participants included in the study were positive for HIV using RDTs. A fourth-generation HIV ELISA and immunoblot assays on DBS confirmed HIV status. Twenty-four out of 25 participants infected with HBV were found positive for hepatitis B surface antigen (HBsAg) using DBS. One sample with a low HBsAg concentration on plasma was not detected on DBS. Five participants tested positive for HCV antibodies were confirmed positive with an immunoblot assay using DBS specimens. Laboratory results were communicated within 7 days to participants with no loss to follow up of participants between the first and second post-test counselling sessions. In conclusion, DBS collection during HIV point-of-care testing enables screening and confirmation of HBV, HCV and HIV infections. Diagnosis using DBS may assist with implementation of national programmes for HBV, HCV and HIV screening and clinical care in middle- to low-income countries.     

新生儿静脉血与脐带血及孕妇静脉血HBV病原学标记物相关性研究

目的 探讨慢性HBV感染孕妇所生新生儿脐带血与静脉血HBV标志物状况的一致性和相关性,以及与孕妇HBV感染标志物的相关性.方法 以HBsAg、HBeAg双阳性且HBV DNA＞1 ×105拷贝/ml孕妇及新生儿为研究对象,孕妇分娩前采集静脉血,新生儿于注射乙肝免疫球蛋白、乙肝疫苗前采集静脉血.在清洁和去除脐带表面污染血液,并用酒精消毒后,用注射器采集脐带血.HBsAg、抗HBs、HBeAg、抗HBe采用雅培微粒子化学发光法(美国雅培公司试剂,Abbott Architac i2000)检测,HBV DNA含量经COBAS TagMan HBV DNA定量检测仪检测.结果 共入组孕妇383例及所生新生儿,静脉血和脐带血HBsAg的阳性检出率分别为61.2％和63.9％,HBeAg阳性检出率分别为83.2％和83.5％,HBV DNA阳性检出率分别为56.0％和59.4％,静脉血和脐带血之间均有一致性.静脉血和脐带血间HBsAg、HBeAg和HBV DNA含量的相关性具有统计学意义(r=0.766、0.857、0.692,P＜0.000).新生儿静脉血和脐带血的HBeAg含量与孕妇的HBeAg含量具有相关性(r=0.362,P=0.000;r=0.352,P=0.000),而静脉血和脐带血的HBsAg含量与孕妇血清的HBsAg含量无相关性(r=0.023,P=0.785;r=0.04,P=0.604).结论 慢性HBV感染孕妇所生新生儿脐带血和静脉血HBV标志物状态有良好的一致性,可以以脐带血的HBV标志物反映新生儿静脉血HBV标志物.