多重环介导核酸等温扩增技术检测血液中常见病原体

背景：血液安全性筛查是输血前必要检测项目。目前临床采用血清学检测技术,存在较长的检测窗口期,易产生假阴性检测结果,造成输血交叉感染。目的：建立多重环介导核酸等温扩增技术,实现在一管反应体系内同时检测四种病原体：乙肝病毒,丙肝病毒,艾滋病毒和梅毒螺旋体。方法：通过限制性酶切处理多重环介导核酸等温扩增产物,利用酶切产物的长度分析扩增产物的种类,从而分析待测样本中含有何种血液病原体。结果：检测164例临床样本,其检测结果可以通过琼脂糖电泳,聚丙烯酰胺凝胶电泳及芯片电泳分析,且均可实现对多重扩增产物的酶切片段进行区分和鉴别。结论：多重环介导核酸等温扩增技术可以同时单管检测多种待测血液病原体,可以为临床提高简单、快速、高灵敏和高特异的检测技术。     

Inactivation and clearance of viruses during the manufacture of high purity factor IX.

Haemophilia is a bleeding disorder characterised by a deficiency in Factor IX. Replacement therapy in the form of a Factor IX concentrate is a widely accepted practice. In this paper we describe a double virus inactivated chromatographic process for producing a high purity Factor IX product, MonoFIX((R))-VF. The process involves separation of the prothrombin complex by cryoprecipitation, fraction I precipitation and DEAE-cellulose adsorption, further ion-exchange chromatography of crude Factor IX, followed by solvent/detergent treatment. Heparin affinity chromatography is then used to further purify Factor IX. Final nanofiltration is sequential through 35 nm then 15 nm membrane filters. The principal virus inactivation/removal steps are solvent/detergent treatment and nanofiltration and the partitioning of relevant and model viruses provides further reduction in virus load through the production process.Solvent/detergent treatment was shown to achieve log reduction factors of 4.5 for HIV-1, 5.1 for Sindbis virus, 6.1 for vesicular stomatitis virus (VSV), 5.1 for bovine viral diarrhoea virus (BVDV) and 5.3 for pseudorabies virus (PRV). BVDV is a model for hepatitis C virus (HCV), and pseudorabies virus (PRV), like hepatitis B virus (HBV) is an enveloped DNA virus. Using scaled down models of the production process, we have also demonstrated the neutralization/partitioning of at least 6 logs of hepatitis A virus (HAV) during cryoprecipitation, Fraction I precipitation, and the DEAE adsorption and elution step, and a further 1.6 log reduction in HAV load as a result of heparin affinity chromatography. The log reduction factors for HAV as a result of the second ion-exchange chromatography step and as a result of enhanced neutralisation associated with solvent/detergent treatment were not significant. Nanofiltration was shown to contribute a further log reduction factor of 6.7 for HAV and 5.8 for BVDV indicating that log reduction factors of this order would be obtained with other viruses of a similar or larger size, such as HIV, HBV and HCV.Overall, these studies indicate that MonoFIX-VF is a product with an extremely high level of viral safety.     

Safety Issues for Plasma Derivatives and Benefit from NAT Testing

Manufacturing processes for plasma derivatives are in general highly effective for removal or inactivation of enveloped viruses and the products are safe with regard to the clinically important viruses HIV, HCV and HBV. They are not so effective for the elimination for non-enveloped viruses, especially Parvovirus B19 (B19). A certain risk remains of B19 contamination for some plasma derivatives that is caused, firstly, by the occurrence of highly contaminated donations (up to 10(14)genomes/ml) and secondly, by the extreme heat resistance and small size of B19 which makes it difficult to remove or inactivate. NAT is a beneficial tool for detection of virus contamination. It is routinely used for the detection of HCV-RNA in plasma pools, thereby preventing the processing of HCV-RNA positive material. NAT assays may also be valuable for testing the removal of viruses during manufacturing. This may be especially important if a virus cannot be tested by infectivity assays.     

病毒性肝炎HAV，HBV，HCV，HDV和HEV重叠感染的研究

采用ＥＬＩＳＡ法检测了１０８例乙型肝炎病毒（ＨＢＶ）感染者血清中的五种肝炎病毒──甲型（ＨＡＶ）、乙型（ＨＢＶ）、丙型（ＨＣＶ）、丁型（ＨＤＶ）和成型（ＨＥＶ）肝炎病毒的标志物,并采用ＰＣＲ技术检测了患者血清ＨＢＶＤＮＡ、ＨＣＶＲＮＡ及ＨＤＶＲＮＡ。结果五种肝炎病毒重叠感染者３５例（３２．４％）,单纯ＨＢＶ感染者７３例（６７．６％）。ＨＢＶ、ＨＡＶＭ重感染率为４．６％,ＨＢＶ、ＨＣＶ二重感染率为９．２％,ＨＢＶ、ＨＤＶＭ重感染率为１４．８％,ＨＢＶ、ＨＥＶ二重感染率为１．９％,ＨＢＶ、ＨＣＶ和ＨＤＶ三重感     

Blood protein derivative viral safety: observations and analysis

The well-documented viral safety of albumin arises from several factors operating in concert, including virus removal during preparation, immune neutralization, serendipitous inactivation, virus sterilization through pasteurization. Safety with respect to HBV transmission was achieved even prior to the development of sensitive screening tests for HBsAg, as can be predicted given the initial virus load and the influence of factors affecting removal and inactivation. Coagulation factor concentrates, as traditionally prepared, are known to have transmitted the viral agents of hepatitis and AIDS with high frequency. Application of virucidal procedures to these concentrates, in some cases, appears to have eliminated virus transmission, raising the question as to whether absolute safety has now been achieved. Clinical proof of absolute safety is made difficult by the small number of eligible patients who can be monitored, lengthy and expensive monitoring procedures, and opportunity for transmission of virus by product-independent routes. Based on viral load analysis, modern coagulation factor concentrates are predicted to have the same probability of freedom from HIV, HBV, and HCV transmission as that exhibited by albumin.     

Dry-heat treatment process for enhancing viral safety of an antihemophilic factor VIII concentrate prepared from human plasma

Viral safety is a prerequisite for manufacturing clinical antihemophilic factor VIII concentrates from human plasma. With particular regard to the hepatitis A virus (HAV), a terminal dry-heat treatment (100 degrees for 30 min) process, following lyophilization, was developed to improve the virus safety of a solvent/detergent-treated antihemophilic factor VIII concentrate. The loss of factor VIII activity during dry-heat treatment was of about 5%. No substantial changes were observed in the physical and biochemical characteristics of the dry-heat-treated factor VIII compared with those of the factor VIII before dry-heat treatment. The dry-heat-treated factor VIII was stable for up to 24 months at 4oC. The dry-heat treatment after lyophilization was an effective process for inactivating viruses. The HAV, murine encephalomyocarditis virus (EMCV), and human immunodeficiency virus (HIV) were completely inactivated to below detectable levels within 10 min of the dry-heat treatment. Bovine herpes virus (BHV) and bovine viral diarrhea virus (BVDV) were potentially sensitive to the treatment. However porcine parvovirus (PPV) was slightly resistant to the treatment. The log reduction factors achieved during lyophilization and dry-heat treatment were > or =5.55 for HAV, > or =5.87 for EMCV, > or =5.15 for HIV, 6.13 for BHV, 4.46 for BVDV, and 1.90 for PPV. These results indicate that dry-heat treatment improves the virus safety of factor VIII concentrates, without destroying the activity. Moreover, the treatment represents an effective measure for the inactivation of non-lipid-enveloped viruses, in particular HAV, which is resistant to solvent/detergent treatment.     

Validation of HCV-NAT Assays and Experience with NAT Application for Blood Screening in Germany

Validation of HCV-NAT assays is an important prerequisite for the use of NAT for screening plasma or blood donations. The main NAT features to be validated are specificity, detection limit and robustness. Preliminary experience in Germany obtained with different methodical and logistic approaches shows the feasibility of HCV-NAT as a screening test for blood donations.     

A Novel Multiplex Real-Time PCR Assay for the Concurrent Detection of Hepatitis A,B and C Viruses in Patients with Acute Hepatitis

A novel multiplex real-time PCR assay for concurrent detection of hepatitis viruses was evaluated for its clinical performance in screening patients with acute hepatitis. A total of 648 serum samples were collected from patients with acute symptoms of hepatitis. Concurrent detection of nucleic acids of HAV, HBV and HCV was performed using the Magicplex™ HepaTrio Real-time Detection test. Serum nucleic acid levels of HBV and HCV were also quantified by the Cobas® AmpliPrep/Cobas® TaqMan® (CAP/CTM) HBV and HCV tests. Patients’ medical records were also reviewed. Concordance rates between the results from the HepaTrio and the CAP/CTM tests for the detection of HBV and HCV were 94.9% (k = 0.88) and 99.2% (k = 0.98), respectively. The cycle threshold values with the HepaTrio test were also correlated well with the levels of HBV DNA (r = −0.9230) and HCV RNA (r = −0.8458). The sensitivity and specificity of the HepaTrio test were 93.8% and 98.2%, respectively, for detecting HBV infection, and 99.1% and 100.0%, respectively, for HCV infection. For the HepaTrio test, 21 (3.2%) cases were positive for both HBV and HCV. Among the positive cases, 6 (0.9%) were true coinfections. This test also detected 18 (2.8%) HAV positives. The HepaTrio test demonstrated good clinical performance and produced results that agreed well with those of the CAP/CTM assays, especially for the detection of HCV. This assay was also able to detect HAV RNA from anti-HAV IgM-positive individuals. Therefore, this new multiplex PCR assay could be useful for the concurrent detection of the three hepatitis viruses.     

Nucleic acid testing (NAT) in high prevalence–low resource settings

Blood screening by NAT for major transfusion transmitted viral infections (TTIs) was originally intended to complement serology for detection of infected donations. Reports from developed countries showed limited marginal value to NAT blood screening in improving blood safety. Reports on NAT results from Europe indicated yield of 1:0.6 million donations for HBV, <1:M for HCV and HIV-1-related to low prevalence of TTI. In contrast, prevalence of TTI in resource-limited countries is almost always high. As a result, more incident cases can be expected among first-time blood donors. Most reports of NAT blood donation screening in these countries showed NAT confirmed yield as high as 1/2800 for HBV and 1/3100 blood donations for HCV as reported from Thailand and Egypt, respectively. The issues for low resource countries are mostly the high cost of NAT but also the requirements of staff qualification, adequate facilities, reagent procurement and maintenance of delicate equipment. Alternatives to commercial NAT are the use of combos antigen-antibody for HIV and HCV, anti-HBc for HBV and in-house NAT. Most of these alternatives have been reported but very few comparisons are available. Once yield data is available, models for estimation of feasibility and cost-effectiveness are proposed to help decision-making.     

A strategy for testing established human plasma protein manufacturing procedures for their ability to inactivate or eliminate human immunodeficiency virus

The manufacturing procedures used for the preparation of human plasma proteins that were established before AIDS was first described may reasonably be expected to provide AIDS safe products. Such manufacturing procedures are heat treatment at 60 degrees C in solution for ten hours, described as pasteurization, preparation of human immunoglobulins by ethanol precipitation, pepsin treatment, and sulfonation. To test whether these methods effectively inactivated and/or eliminated the AIDS causing human immunodeficiency virus (HIV), nine volumes or more of plasma or a plasma fraction taken from a production lot were spiked with HIV using one volume of a HIV concentrate and were then subjected to exactly the same procedure as that specified for the manufacturing process. HIV infectivity titres of the initial HIV/plasma protein mixtures and of the resulting products after treatment were determined by the H9 cell assay. In all cases studied complete inactivation/elimination of the added HIV was achieved. We therefore conclude that pasteurization of human plasma proteins or the manufacturing procedure used for the isolation of immunoglobulins from plasma pools result in final products which do not contain any infectious HIV and which are thus safe in that they cannot be vehicles for the transmission of AIDS.     

Deceased tissue donor serology and molecular testing for HIV,hepatitis B and hepatitis C viruses: a lack of cadaveric validated tests

Vital to patient safety is the accurate assessment and minimization of risk for human immunodeficiency virus (HIV), Hepatitis C (HCV), and Hepatitis B (HBV) virus transmission by deceased donor organ and tissue transplantation. The pathogens are tested by serological kits based on enzyme-linked immunosorbent assay (ELISA), chemiluminescence (CLIA) and eletrochemiluminescence (ECLIA) immunoassays. Organ transplantation is a highly successful life-saving treatment in Brazil, but the Brazilian Health Surveillance Agency currently mandates that all deceased organ donors are screened for HIV, HCV and HBV following living donor policies. In this review, six ELISA (Wama^®, Bio-Rad^®, Biomerieux^®, DiaSorin^®, Acon Biotech^® and Biokit^®), three CLIA (Abbott^®, Siemens^®, Diasorin^®) and one ECLIA (Roche^®) were utilized for evaluating the effectiveness of those serological tests for deceased donors in Brazil according to manufacturer’s guidelines. NAT for HIV, HCV and HBV can assist with detection of pre-seroconversion for those infections, and only Cobas^® TaqScreen MPX^® test, the Tigris System^® Procleix Ultrio Assay^® and the Bio-Manguinhos^® HIV/HCV/HBV NAT are commercially available. Between all the tests, only the manufacturer Abbott^® and Cobas^® TaqScreen MPX^® test are currently validated for cadaver samples.     

Liver transplantation for patients infected with both HIV and HCV or HIV and HBV

Human immunodeficiency virus infection (HIV) has been considered until recently as a contraindication for liver transplantation. This was due to the poor spontaneous prognosis of HIV infection. The advent of highly active antiretroviral drugs (HAART) was a therapeutic breakthrough, and the prognosis has been dramatically improved. 30 % and 10 % of HIV infected patients are coinfected with hepatitis C virus (HCV) and with hepatitis B virus (HBV), respectively. The progression of chronic hepatitis B and C seems more rapid in coinfected patients, and a high number of patients will develop life-threatening liver cirrhosis. There are numerous potential problems raised by liver transplantation in HIV infected patients: (1) the potential risk of needlestick injury during this type of hemorrhagic surgery at high risk of bleeding; (2) the timing for liver transplantation; (3) the risk of interference between HAART and calcineurin inhibitors; (4) The risk of HBV and HCV recurrence post-transplant. Since 1999, a program of liver transplantation has been started in patients coinfected with HIV and HBV or HCV with the support of the Agence Nationale de Recherche contre le Sida et les Hépatites virales (ANRS). The first results showed that liver transplantation in HIV-HCV and HIV-HBV infected patients is feasible, achieving 2-year survival of 70 % and 100 %, respectively. There was no acceleration of HIV disease after transplantation. HBV recurrence was well prevented by the combination of anti-HBs immunoglobulins plus nucleoside and nucleotide analogues effective against HBV. The main problem is HCV recurrence, which is more rapid and more severe in HIV coinfected patients than in HCV monoinfected patients. Understanding HCV recurrence mechanisms, and preventing and treating of HCV recurrence are major future challenges.     

High Prevalence of HIV, HCV, HBV and Co-Infection and Associated Risk Factors among Injecting Drug Users in Yunnan Province, China

Objective

To estimate the prevalence of HIV, HCV, HBV and co-infection with 2 or 3 viruses and evaluate risk factors among injecting drug users (IDUs) in Yunnan province, China.

Methods

2080 IDUs were recruited from 5 regions of Yunnan Province, China to detect the infection status of HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV). Statistical analysis was performed to evaluate risk factors related to HIV, HCV and HBV infections.

Results

The infection rates among all participants were 25.5% for HIV, 77.7% for HCV, 19.2% for HBV, 15% for HIV/HCV, 0.3% for HIV/HBV, 7.8% for HCV/HBV and 7.1% for HIV/HCV/HBV. The prevalence of virus infection varied widely by region in Yunnan of China. Statistical analyses indicated that high prevalence of HIV and HCV among IDUs was positively associated with the duration of drug injection and sharing needles/syringes; besides, HCV infection was associated with the frequency of drug injection.

Conclusions

HIV, HCV, HBV infections and co-infections were still very prevalent among IDUs in Yunnan province because of drug use behaviors.     

Health economics of blood transfusion safety – focus on sub-Saharan Africa

Background and objectivesHealth economics provides a standardised methodology for valid comparisons of interventions in different fields of health care. This review discusses the health economic evaluations of strategies to enhance blood product safety in sub-Saharan Africa.MethodsWe reviewed health economic methodology with special reference to cost-effectiveness analysis. We searched the literature for cost-effectiveness in blood product safety in sub-Saharan Africa.ResultHIV-antibody screening in different settings in sub-Saharan Africa showed health gains and saved costs. Except for adding HIV-p24 screening, adding other tests such as nucleic acid amplification testing (NAT) to HIV-antibody screening displayed incremental cost-effectiveness ratios greater than the WHO/World Bank specified threshold for cost-effectiveness. The addition of HIV-p24 in combination with HCV antibody/antigen screening and multiplex (HBV, HCV and HIV) NAT in pools of 24 may also be cost-effective options for Ghana.ConclusionsFrom a health economic viewpoint, HIV-antibody screening should always be implemented in sub-Saharan Africa. The addition of HIV-p24 antigen screening, in combination with HCV antibody/antigen screening and multiplex (HBV, HCV and HIV) NAT in pools of 24 may be feasible options for Ghana. Suggestions for future health economic evaluations of blood transfusion safety interventions in sub-Saharan Africa are: mis-transfusion, laboratory quality and donor management.     

NAT: Perspectives for Cellular Components

The introduction of routine testing to detect viral genomes in donated blood was originally driven by requirements for plasma fractionation in relation to exclusion of hepatitis C virus (HCV) RNA. Nevertheless, it was obvious from the outset that a dual standard for fractionated products and individual blood components would be untenable. In many countries therefore, planning for introduction of nucleic acid testing (NAT) of blood incorporated progression to release of HCV RNA tested components. HCV was singled out because of its long seronegative 'window period', relatively high prevalence and incidence in blood donors, rapid burst time and high genome copy number during seroconversion. The latter properties made HCV particularly suitable for detection in pools of samples. If HCV RNA testing is required for release of labile components such as platelets, rapid provision of NAT results is vital because of short shelf life of platelets and the problems of delays when resolving the infectious unit in a reactive pool. For NAT release of labile components smaller sample pool sizes allow faster resolution of RNA positive units. Smaller pools involve high test throughput, the likely need for more testing laboratories and ensuing increased costs. Single sample testing is the ultimate extrapolation of reducing sample pool size. With reduced pool sizes or single sample testing, the option of testing for other viruses (e.g. HIV or HBV) singly or in multiplex also arises. The cost-benefit and incremental yield of such strategies in the light of 'combo' assays for HIV Ag/Ab and the recently described HCV Ag assay will require careful and objective assessment, together with re-appraisal of anti-HBc screening for detection of HBV infected donors at the "tail-end" of carriage.     

Antibodies against HBV, HCV and HAV detected by using microparticle enzyme immunoassay in hepatitis outpatients

The presence of the hepatitis B surface antigen (HBsAg), of the antibodies against HBc, HCV and HAV was determined in outpatients in the period September 2005 - December 2006. The serum samples were analyzed by using Enzyme Immunoassay microparticles (Abbott AxSYM System). At least one test was positive in 238 patients (15.4%) of the total of 1547 patients. Of the 238 positive subjects, in 130 positive subjects (54.6%) the existence of HBV infection could be ascertained based on the presence of HBsAg or of the antibodies against HBc or of their association; 83 patients (34.9%) presented antibodies against HCV and in other 12 patients the antibodies against HCV were associated with HBsAg or with antibodies against HBc, suggesting the coexistence of HCV and HBV infection. The antibodies against HCV and the associations between HCV and HBV were mostly detected in subjects with the diagnosis of cirrhosis, liver failure or chronic hepatitis. Of the 13 (5.46%) patients with antibodies against HAV, 6 patients presented the associations: in 2 cases antibodies anti-HAV with positive HBsAg, in 1 case antibodies anti-HAV and anti-HBc with positive HBsAg, in 2 cases antibodies anti-HAV and anti-HBc and in 1 case antibodies anti-HAV and anti-HCV.     

Safety aspects in the manufacturing of plasma-derived coagulation factor concentrates.

Plasma-derived coagulation factor concentrates, prepared using traditional manufacturing processes, have transmitted viral diseases, especially AIDS, hepatitis B and hepatitis C to patients. To date, more extensive selection of blood donors, improved screening procedures of each plasma donation for direct and indirect viral markers, and newly developed virucidal procedures, especially pasteurization and solvent-detergent, together with extraction technologies of plasma proteins based on high-resolution chromatographic separations, have diminished considerably the risks of transmitting these pathogenic agents. To ensure safety, each production process must be carefully validated, following a rigorous scientific approach to assess its ability to inactivate or eliminate viruses. In addition, Good Manufacturing Practices must avoid any variation from these validated viral inactivation processes and must eliminate risks of potential downstream contamination of purified plasma fractions following viral inactivation or elimination steps. Other side-effects associated with conventional low-purity preparations, such as acute haemolytic anemia due to contamination by isohaemagglutinins, or immunosuppression possibly due to an overload in fibrinogen and immunoglobulins, have not been reported following infusion of highly purified coagulation factor concentrates. Present state-of-the-art virus inactivation and protein-purification technologies have significantly improved the safety of plasma coagulation factor concentrates.     

The role of triple infection with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus (HIV) type-1 on CD4+ lymphocyte levels in the highly HIV infected population of North-Central Nigeria

We set out to determine the seroprevalence of hepatitis B and C among human immunodeficiency virus type-1 (HIV-1) infected individuals in North-Central Nigeria to define the influence of these infections on CD4+ lymphocytes cells among our patients as access to antiretroviral therapy improves across the Nigerian nation. The CD4+ values of 180 confirmed HIV-1 infected individuals were enumerated using a superior fluorescence-activated cell sorter system. These patients were tested for the presence of hepatitis B surface antigen and anti-hepatitis C virus (HCV) using third generation enzyme-linked immunosorbent assays. Fifty (27.8%) patients had active hepatitis B virus (HBV) infection while 33 (18.3%) tested positive for anti-HCV antibody. Of these infections, 110 (61.1%), 37 (20.6%), and 20 (11.1%) had HIV only, HBV/HIV-only, and HCV/HIV-only respectively. A HBV/HCV/HIV coinfection prevalence of 7.2% (13 patients) was recorded. Patients coinfected with HIV/HBV/HCV appeared to have lower CD4+ counts (mean = 107 cells/microl; AIDS defining) when compared to HBV/HIV-only (mean = 377 cells/microl), HCV/HIV-only (mean = 373 cells/microl) and patients with mono HIV infection (mean = 478 cells/microl). Coinfection with HBV or HCV is relatively common among HIV-infected patients in Nigeria and should be a big consideration in the initiation and choice of therapy.