Yield of HCV and HIV-1 NAT after screening of 3.6 million blood donations in central Europe

Pooled testing: A tool to increase efficiency of infant HIV diagnosis and virological monitoring

Background

Pooled testing, or pooling, has been used for decades to efficiently diagnose relatively rare conditions, such as infection in blood donors. Programmes for the prevention of mother-to-child transmission of HIV and for antiretroviral therapy (ART) are being rolled out in much of Africa and are largely successful. This increases the need for early infant diagnosis (EID) of HIV using qualitative nucleic acid testing and for virological monitoring of patients on ART using viral load testing. While numbers of patients needing testing are increasing, infant HIV infections and ART failures are becoming rarer, opening an opportunity for pooled testing approaches.

Aim

This review highlights the need for universal EID and viral load coverage as well as the challenges faced. We introduce the concept of pooled testing and highlight some important considerations before giving an overview of studies exploring pooled testing for EID and virological monitoring.

Results

For ART monitoring, pooling has been shown to be accurate and efficient; for EID it has not been tried although modelling shows it to be promising. The final part attempts to place pooling into the context of current mother-to-child transmission of HIV and ART programmes and their expected trajectories over the next years.

Conclusion

Several points warrant consideration: pre-selection to exclude samples with an elevated pre-test probability of positivity from pooled testing, the use of dried blood or plasma spots, and choosing a pooling strategy that is both practically feasible and economical. Finally, novel ideas are suggested to make pooling even more attractive.

Genotyping & diagnostic methods for hepatitis C virus: A need of low-resource countries

Hepatitis C virus (HCV) infection is a blood borne and transfusion-transmitted infection (TTI). It has emerged as one of the major health challenges worldwide. In India, around 12-18 million peoples are infected with HCV, but in terms of prevalence percentage, its looks moderate due to large population. The burden of the HCV infection increases due to lack of foolproof screening of blood and blood products before transfusion. The qualified screening and quantification of HCV play an important role in diagnosis and treatment of HCV-related diseases. If identified early, HCV infection can be managed and treated by recently available antiviral therapies with fewer side effects. However, its identification at chronic phase makes its treatment very challenging and sometimes ineffective. The drugs therapy for HCV infection treatment is also dependent on its genotype. Different genotypes of HCV differ from each other at genomic level. The RNA viruses (such as HCV) are evolving perpetually due to interaction and integration among people from different regions and countries which lead to varying therapeutic response in HCV-infected patients in different geographical regions. Therefore, proper diagnosis for infecting virus and then exact determination of genotype become important for targeted treatment. This review summarizes the general information on HCV, and methods used for its diagnosis and genotyping.

Epidemiological trends of HIV-1 infection in blood donors from Catalonia, Spain (2005-2014)

BACKGROUND

Human immunodeficiency virus 1 (HIV-1) subtype B is predominant in Spain. However, the recent arrival of immigrant populations has increased the prevalence of non-B subtypes and circulating recombinant forms. The objective of this study was to determine the prevalence of HIV-1 subtypes and transmitted drug-resistance mutations in blood donors from the Catalonian region (northeastern Spain).

STUDY DESIGN AND METHODS

HIV-1-positive blood donors identified in Catalonia from 2005 to 2014 were included. Demographic variables and risk factors for HIV-1 acquisition were recorded. HIV-1 subtyping was carried out by HIV-1 DNA polymerase region sequencing, and phylogenetic analyses were performed using the neighbor-joining method.

RESULTS

During the study period, 2.8 million blood donations were screened, and 214 HIV-1-positive donors were identified, yielding an overall prevalence of 7.7 per 100,000 donations (89% men; mean age, 34 ± 10 years). Most HIV-1-positive donors were native to Spain (81%), and 61% were regular blood donors. When risk factors were known, 62% reportedly were men who had sex with men. HIV-1 subtyping was possible in 176 HIV-1-positive individuals: 143 (81%) had HIV-1 subtype B, and 33 (19%) had non-B subtypes. Most HIV-1 non-B subtypes were circulating recombinant forms (n = 20; 61%). Factors associated with HIV-1 subtype B were male sex (p = 0.007) and men who had sex with men (p < 0.001). The overall prevalence of transmitted drug-resistance mutations was 14%.

CONCLUSION

Non-B subtypes, circulating recombinant forms, and transmitted drug-resistance mutation sequences circulate among HIV-1-positive blood donors in Catalonia. Continuous local epidemiological surveillance is required to implement optimal prevention strategies for controlling transfusion-transmitted HIV and to improve health policies regarding HIV infection.

Hepatitis C virus infection in southwestern Saudi Arabia: Are we still in the plateau phase?

The aim was to study the seroprevalence of Hepatitis C virus (HCV) infection and related risk factors in Aseer region in southwestern Saudi Arabia, the region known to be of the highest endemicity of viral hepatitis. In a cross-sectional study, all participants were interviewed using structured questionnaire. HCV infection was diagnosed using fourth-generation ELISA. All positive and equivocal HCV serology results were further confirmed by using a qualitative confirmatory RT-PCR. The study enrolled 10,234 participants. A seroprevalence of 2.2% (95%CI: 1.9-2.5%) was found. In multivariate logistic regression analysis, the study showed that males had significantly more risk to become seropositive for HCV (aOR = 1.437, 95%CI: 1.071-1.927) compared to females. Similarly, participants having history of blood transfusion had more than two times the risk of becoming seropositive for HCV (aOR = 2.079, 95%CI: 1.037-4.149). HCV infection in the study area is still high in the plateau phase. It is recommended to have an active educational and media campaign about the risks of HCV infections. Workshops and training of qualified laboratory staff related to blood banking seem mandatory. J. Med. Virol. 89:867-871, 2017. © 2016 Wiley Periodicals, Inc.

The proportion and trend of human immunodeficiency virus infections associated with men who have sex with men from Chinese voluntary blood donors: a systematic review and meta-analysis

BACKGROUND

Human immunodeficiency virus (HIV)-positive cases associated with men who have sex with men (MSM) have rapidly increased over the past years. The objective of this study is to comprehensively evaluate the proportions, changing trends, and geographical distribution of MSM-associated HIV cases from Chinese voluntary blood donors by systematically reviewing the available literature.

STUDY DESIGN AND METHODS

Major English and Chinese research databases were searched for studies reporting study locations, study years, the number of HIV infections among blood donors, and the number of HIV-positive donations associated with MSM in China. The proportion estimates were calculated; subgroup analyses and test for time trend were performed using software of comprehensive meta-analysis.

RESULTS

Thirty-four studies met eligibility criteria. The pooled proportion of HIV-positive donations associated with MSM from 2001 to 2012 was 36.5% (95% confidence interval, 29.6%-44.1%). The epidemic was found to be more severe in northeast and north China compared to south China (59.6%; 55.0% vs. 3.8%, respectively). The proportion showed a significantly increasing trend over the study period (10.3% in 2001-2005; 38.6% in 2006-2009; and 47.6% in 2010-2012; trend test chi-square = 16.42, p < 0.001).

CONCLUSION

The relatively high proportion of MSM- associated HIV-positive donors is of concern. Efficient and effective measures focused on public education and improving knowledge of blood safety are needed to prevent this at-risk population from seeking HIV testing through blood donation. It is also imperative to expand the scope of postdonation nucleic acid testing to shorten the window period to improve blood supply safety in China.

Half a decade of mini-pool nucleic acid testing: Cost-effective way for improving blood safety in India

BACKGROUND AND OBJECTIVES

It is well established that Nucleic acid testing (NAT) reduces window phase of transfusion transmissible infections (TTI) and helps improve blood safety. NAT testing can be done individually or in pools. The objectives of this study were to determine the utility, feasibility and cost effectiveness of an in-house minipool-NAT(MP-NAT).

MATERIALS AND METHODS

Blood donors were screened by history, tested by ELISA and sero-negative samples were subjected to an in-house NAT by using reverse transcriptase-polymerase chain reaction (RT-PCR). Testing was done in mini-pools of size eight (8). Positive pools were repeated with individual samples.

RESULTS

During the study period of Oct 2005-Sept 2010 (5 years) all blood donors (n=53729) were screened by ELISA. Of which 469 (0.87%) were positive for HIV-1, HBV or HCV. Sero-negative samples (n=53260) were screened by in-house MP-NAT. HIV-NAT yield was 1/53260 (n=1) and HBV NAT yield (n=2) was 1/26630.

CONCLUSION

NAT yield was lower than other India studies possibly due to the lower sero-reactivity amongst our donors. Nevertheless it intercepted 9 lives including the components prepared. The in-house assay met our objective of improving blood safety at nominal cost and showed that it is feasible to set up small molecular biology units in medium-large sized blood banks and deliver blood within 24-48 hours. The utility of NAT (NAT yield) will vary based on the donor population, the type of serological test used, the nature of kit employed and the sensitivity of NAT test used. The limitations of our in-house MP-NAT consisted of stringent sample preparation requirements, with labor and time involved. The benefits of our MP-NAT were that it acted as a second level of check for ELISA tests, was relatively inexpensive compared to ID-NAT and did not need sophisticated equipment.

Current testing strategies for hepatitis C virus infection in blood donors and the way forward

Screening tests for blood donations are based upon sensitivity, cost-effectiveness and their suitability for high-throughput testing. Enzyme immunoassay (EIAs) for hepatitis C virus (HCV) antibodies were the initial screening tests introduced. The ”first generation“ antibody EIAs detected seroconversion after unduly long infectious window period. Improved HCV antibody assays still had an infectious window period around 66 d. HCV core antigen EIAs shortened the window period considerably, but high costs did not lead to widespread acceptance. A fourth-generation HCV antigen and antibody assay (combination EIA) is more convenient as two infectious markers of HCV are detected in the same assay. Molecular testing for HCV-RNA utilizing nucleic acid amplification technology (NAT) is the most sensitive assay and shortens the window period to only 4 d. Implementation of NAT in many developed countries around the world has resulted in dramatic reductions in transfusion transmissible HCV and relative risk is now < 1 per million donations. However, HCV serology still continues to be retained as some donations are serology positive but NAT negative. In resource constrained countries HCV screening is highly variable, depending upon infrastructure, trained manpower and financial resource. Rapid tests which do not require instrumentation and are simple to perform are used in many small and remotely located blood centres. The sensitivity as compared to EIAs is less and wherever feasible HCV antibody EIAs are most frequently used screening assays. Efforts have been made to implement combined antigen-antibody assays and even NAT in some of these countries.

How safe is safe: new human immunodeficiency virus Type 1 variants missed by nucleic acid testing

BACKGROUND

Nucleic acid amplification techniques (NAT) in routine blood donor screening considerably reduce the diagnostic window phase period. Nevertheless, several reports of false-negative NAT results were published. Here, four cases of human immunodeficiency virus Type 1 (HIV-1) RNA-positive blood donations that escaped detection by NAT screening are described.

STUDY DESIGN AND METHODS

A total of 2.7 million blood donations were screened for viral infections between January 2010 and October 2012 in our German Red Cross blood donation service. Four plasma specimens with false-negative NAT results were comparatively investigated with 12 CE-marked NAT assays. In two cases of putative HIV-1 variants the target region of the NAT assay was sequenced allowing comparison with the respective primers and probes.

RESULTS

Most of the NAT assays used in routine blood donor screening with the 5'-long terminal repeat (LTR) as target region demonstrated deficiencies in detecting the viral variants and the low-viral-carrier donations. Sequence analysis revealed in one case a deletion of 56 nucleotides within the 5'-LTR preventing the binding of the probe accompanied by a neighbored insertion of another 52 nucleotides and several primer mismatches in another case. No false-negative results were obtained for these cases using dual-target assays. The viral load of the remaining two false-negative results was below the NAT's limit of detection.

CONCLUSION

HIV-1 is characterized by a high mutation rate and rapid generation of new viral variants. By the use of one target region for HIV-1 NAT assays there is a certain risk of false-negative results. Employing HIV-1 multi- and dual-target assays in routine blood donor screening seems to be a reasonable possibility to minimize this problem.

New tools in HCV diagnosis, in light of the enhanced awareness and the new drugs for treatment: SMARTube and stimmunology

With improved HCV therapy, challenges regarding HCV diagnosis, such as seronegative window period, false positive readings, and differentiation between recent, chronic, and resolved infections, are of increasing importance. To address these challenges an innovative device—SMARTube HIV & HCV—was used. Blood samples were tested for anti-HCV antibodies before and after incubation in the SMARTube, which promotes the in vitro stimulation of in vivo HCV primed lymphocytes, thus enhancing levels of anti-HCV antibodies. Comparing antibody levels, in concordant samples before and after SMARTube, yielded the Stimulation Index (SI). Among 5888 fresh blood samples, from various populations and regions worldwide, 641 were seropositive using plasma, while SMARTube processing (yielding enriched plasma, termed SMARTplasma) enabled diagnosis of 10 additional carriers in high-risk cohorts, that is, earlier detection. Using SMARTplasma eliminated all false positive results, using the current assays. In addition we show that SI calculation may serve as an important tool for differentiating between those who recently seroconverted, carriers of long-term infection, and those who have cleared the virus. SMARTube and the SI could lead to better, more informative diagnosis of HCV infections and play an important role in changing the way we treat both the infected individuals and the epidemic as a whole.

Pooling nasopharyngeal/throat swab specimens to increase testing capacity for influenza viruses by PCR

Real-time PCR methodology can be applied to rapidly and accurately detect influenza viruses. During times of surge testing or enhanced pandemic surveillance, public health laboratories (PHLs) may experience overwhelming demand for testing, even while the prevalence of positive specimens remains low. To improve laboratory capacity and testing efficiency during surges, we evaluated whether nasopharyngeal (NP)/throat swab specimens can be pooled and tested for the presence of the 2009 H1N1 influenza virus without a reduction in sensitivity. Pools of 10 specimens were extracted and concentrated upon elution on the MagNA Pure LC instrument, and real-time PCR was performed on the Applied Biosystems 7500 Fast platform, using the CDC swine influenza virus real-time RT-PCR detection panel (rRT-PCR swine flu panel). Specimens in positive pools were singly re-extracted and retested by PCR to identify individual positive samples. Initial studies showed that spiking a pool of nine negative specimens (100 μl each) or 900 μl of virus transport medium with 100 μl of a positive clinical specimen caused no loss of sensitivity by rRT-PCR testing. Pools containing either multiple positive specimens or specimens positive for other respiratory viruses also showed no negative effect on crossing threshold (C(T)) values. To test the robustness of the pooling protocol, a panel of 50 blinded samples was sent to three PHLs and tested in five pools of 10. All PHLs correctly identified the positive specimens. This study demonstrates the feasibility of using a pooling strategy to increase capacity and conserve resources during surge testing and periods of enhanced influenza surveillance when the prevalence is low.

Case report of a haemovigilance investigation using phylogenetic analysis of HIV-1 in Brazil

OBJECTIVES

The aim of this work is to provide the first report of a transfusion-acquired HIV-1 infection and to verify transmission from the donor to the recipients using phylogenetic analysis of HIV-1 DNA sequences in a Brazilian blood bank.

BACKGROUND

Although haemovigilance procedures based on phylogenetic analysis of HIV have been reported in several countries, this type of study has yet to be conducted in Latin America.

MATERIALS AND METHODS

Upon identifying a HIV-1-positive repeat blood donor by enzyme immunoassay (EIA) blood screening, all recipients of the donor's previous donation were identified and tested for HIV-1 by EIA, nucleic acid amplification test and HIV-1 DNA sequencing and phylogenetic analysis.

RESULTS

One of the recipients tested positive for HIV-1. The phylogenetic analysis showed a high genetic similarity among the viruses, thus supporting the hypothesis of transmission from the donor to the recipient.

CONCLUSIONS

Phylogenetic analysis of HIV-1 DNA sequences has been a decisive tool in verifying suspected transmission of the virus from blood donor to recipient in Brazil.

Prevalence of congenital cytomegalovirus infection in Slovenia: a study on 2,841 newborns

Human cytomegalovirus (CMV) is the most frequent cause of congenital infection in humans. In the first prevalence study of congenital CMV infection in Eastern and Central Europe, all neonates born in a 22-month period in two Slovenian maternity units (total of 2,841 newborns) were screened prospectively for congenital CMV infection by a real-time polymerase chain reaction (PCR) in urine. In all newborns with positive screening results, plasma and dried blood spots (DBS) collected at birth were tested additionally for CMV DNA. Congenital CMV infection was confirmed by virus isolation from a urine sample collected within the first 2 weeks of life. Congenital CMV infection was identified in four out of 2,841 newborns tested (incidence 0.14%; 95% CI, 0.05-0.39%). In four newborns with confirmed congenital infection, the concentration of CMV DNA in urine ranged from 4.68 to 8.18 log(10)  copies/ml, all four newborns had detectable CMV DNA in plasma taken at birth (1.26-3.34 log(10)  copies/ml) and two out of four had detectable CMV DNA in DBS collected during newborn metabolic screening. None of the four newborns with confirmed congenital CMV infection was symptomatic. The study showed that the prevalence of congenital CMV infection at birth in Slovenia is among the lowest in the world and that CMV DNA PCR testing of urine is a suitable and affordable real-time screening strategy for congenital CMV infection. If it is performed in 24 mini-pools, the cost of screening is 1.4 €/newborn and the cost of detecting a single newborn with congenital CMV infection 1,000 €.

Genomic detection of human immunodeficiency virus (HIV) by nucleic acid amplification test in a frequent platelet donor during the pre-seroconversion period

Since serological donor-screening tests for HIV were introduced in 1985, the safety of donated blood components has improved dramatically. However, these tests do not completely prevent the risk of transfusion-associated HIV infection related to the use of blood donated during the pre-seroconversion window period. Testing based on nucleic acid amplification is being implemented to screen for HIV-infected blood donated during this period, which has reduced the probability of transmitting HIV through transfusion by shortening the window period. This article describes a case of acute HIV-1 infection, detected using a nucleic acid amplification test (NAT) in a repeat blood donor who donated during the pre-seroconversion window period and whose antigen and anti-HIV antibody expression was observed after molecular marker detection. In addition, the possible route of infection is discussed based on the patient's history, and finally, the need for NAT technology for blood donor screening is emphasized.

The introduction of intra-operative cell salvage in obstetric clinical practice: a review of the available evidence

Intra-operative blood salvage is common practice in many surgical specialties but its safety is questioned with concerns about the risks of contamination of recovered blood with amniotic fluid and of maternal-foetal alloimmunization. However, the role of cell salvage as a blood-saving measure in this clinical setting is progressively acquiring relevance thanks to the growing body of evidence regarding its quality and safety. Modern cell savers remove most particulate contaminants and leukodepletion filtering of salvaged blood prior to transfusion adds further safety to this technique. Amniotic fluid embolism is no longer regarded as an embolic disease and the contamination of the salvaged blood by foetal Rh-mismatched red blood cells can be dealt with using anti-D immunoglobulin; ABO incompatibility tends to be a minor problem since ABO antigens are not fully developed at birth. Maternal alloimmunization can be caused also by other foetal red cell antigens, but it should also be noted that the risk of alloimmunization of the mother from allogeneic transfusion may be even greater. Therefore the use of cell savers in obstetric clinical practice should be considered in patients at high risk for haemorrhage or in cases where allogeneic blood transfusion is difficult or impossible.

Evaluation of pooled rapid HIV antibody screening of patients admitted to a San Diego Hospital

Current HIV screening guidelines in the United States recommend expanding the scope of HIV screening to include routine screening in health care settings; however, this will require increased resources. Since testing of pooled samples can decrease costs, the test characteristics of pooled rapid antibody testing were determined and optimal pool sizes were estimated for populations with HIV prevalence ranging from 0.25% to 10%. Based on these results, pooled testing methods were evaluated for screening patients admitted to hospital in San Diego, California. Evaluation of pooled antibody testing on samples collected from individuals with known HIV infection found only a modest reduction in sensitivity. These false negative results were only found among samples with very low optical density readings (<0.125 by the ADVIA Centaur® HIV assay). These readings are considered as HIV negative by the ADVIA Centaur® HIV assay, and therefore likely correspond to samples collected during acute infection. Further evaluation of pooled testing of samples collected from individuals during recent infection, found that mini-pool testing of five samples detected HIV antibody in 86% of samples taken within 60 days of the initial infection and 92% of samples taken within 90 days of the initial infection. Based on estimations of optimal pool sizes for low prevalence populations, it was decided to evaluate mini-pools consisting of 10 samples to screen the study's hospitalized patients. During this evaluation, the HIV prevalence among hospitalized patients was 0.8%, and the 10 sample mini-pool testing had 100% sensitivity and specificity. Additionally, pooled testing resulted in an 84.5% reduction in the number of rapid HIV antibody tests needed, as compared to testing each sample individually. Even when incorporating the increased costs of technician time, mini-pooled tested would have resulted in a net savings of 8760 USD for the 523 samples tested in the study. Taken together, these results indicate that pooled rapid antibody testing may reduce substantially the costs for HIV screening in low prevalence populations without a loss in accuracy.

Quarantine Plasma: Quo vadis?

Upon the introduction of mandatory nucleic acid amplification technology (NAT) testing in Germany for HCV, quarantining of fresh frozen plasma (FFP) was reduced in 2002 from 6 to 4 months. In 2004 HIV-1 NAT and in 2005 anti-HBc testing were introduced to further reduce the residual transmission risks for transfusion relevant viruses. After testing more than 40 million donations by HCV NAT it became obvious that NAT testing has a very significant impact on viral blood safety by reducing the residual risk by a factor of 10. Only one documented HCV transmission occurred during more than 10 years of NAT testing in Germany, indicating that the remaining risk is marginal. Similar data were obtained for HIV-1. The question arises whether we could discontinue quarantining of FFP or further reduce the quarantining interval for retesting of the donor. This could facilitate logistics and reduce losses as quarantine FFP can be released earlier after donation and at regular donation intervals. Essential parameters for estimating the remaining infectious risks are the minimal infectious dose and replication kinetics of the viruses involved, the detection limits of the NAT tests applied, and the volume of plasma transfused. In essence it can be assumed that discontinuation of quarantining would only marginally increase the residual risk and that the reduction of the quarantine period to only 4 weeks would add an additional benefit to the viral safety of quarantine FFP.

Blood donor screening with cobas s 201/cobas TaqScreen MPX under routine conditions at German Red Cross institutes

BACKGROUND

In 1997 the German Red Cross (GRC) blood donor services introduced mini-pool nucleic acid testing (NAT) for human immunodeficiency virus (HIV)-1, hepatitis C virus (HCV) and hepatitis B virus (HBV) to increase blood safety. With the new cobas s 201/cobas TaqScreen MPX, a fully automated extraction method and a multiplex amplification system specifically adapted to the needs of blood donation services is available.

METHODS

The cobas s 201 system was evaluated at the GRC BTS locations Hagen, Springe and Frankfurt. In phase A, the analytical sensitivity for the detection of HBV, HCV and HIV-1 was investigated and in phase B, at least 60,000 samples at each test site were screened in parallel with the MPX test on s 201 system and the existing routine mini-pool NAT system to compare the diagnostic specificity and the diagnostic sensitivity.

RESULTS

Comparable analytical sensitivities in a range of 1.6-3.6 IU/ml, 4.9-10.9 IU/ml and 14.7-26.6 IU/ml for HBV, HCV HIV, respectively, for the MPX test on s 201 system (95% probability based on probit analysis) were determined at all test sites. The diagnostic sensitivity was 99.8% and the diagnostic specificity was 99.85%.

CONCLUSIONS

The MPX test on s 201 system is a fully automated NAT system suitable for routine blood donor screening. The analytical sensitivity as well as the diagnostic sensitivity fulfilled all requirements of the Paul Ehrlich Institute for blood donor screening in mini-pools up to 96 donations per pool. A major benefit of the automated NAT system is the reduced personnel time and the extensive complete barcode-controlled process documentation.

The value of increased neopterin levels in reducing transfusion-transmitted virus infections: detection of a donation from a HBsAg positive chronic carrier by screening of neopterin in Turkish blood donors

Neopterin is an early, sensitive and non-specific marker of cellular immunity. In the present study, serum levels of neopterin were measured by ELISA in 2760 volunteer blood donors, all negative by routine screening tests. Neopterin concentrations ranged from 0.001 to 62.1 nmol/l. 141 donors (5.1%) were found to have high (> or =11 nmol/l) neopterin levels, and 57 of them accepted further investigations within about 3 weeks after their donation. Six had clinical symptoms, and 7 were positive for viral markers. Retesting of neopterin revealed that 2 of 57 donors still showed elevated results, who were adenovirus IgM and HBsAg positive donors, respectively. The present detection of a HBsAg positive donor who yielded negative result initially and a patient with adenovirus infection indicates that routine screening of neopterin levels in blood banks may reduce the risk for viral transmission.

One-year experience of nucleic acid technology testing for human immunodeficiency virus Type 1, hepatitis C virus, and hepatitis B virus in Thai blood donations

BACKGROUND

Blood donations collected at the National Blood Center, the Thai Red Cross Society, Bangkok, in 2007 were tested by nucleic acid amplification technology (NAT) using the Chiron TIGRIS/Procleix Ultrio test and the Roche cobas s 201/cobas TaqScreen multiplex (MPX) test.

STUDY DESIGN AND METHODS

The sensitivity, specificity, and robustness were determined by testing 486,676 seronegative blood donations. Samples from each day of collection were divided into two sets; the odd-numbered samples were tested individually on the TIGRIS and the even-numbered samples were tested in pools of 6 on the cobas s 201. The status of reactive samples was confirmed by duplicate testing of samples from the plasma bag to calculate the test specificity. Reactive samples were tested on the alternate system and followed up.

RESULTS

The analytical sensitivity of both systems met the 95% limits of detection claimed by the respective package inserts. No cross contamination was seen with either system. Test specificity was 99.93 and 99.90% for the Procleix Ultrio and cobas TaqScreen tests, respectively. The NAT yield rates for human immunodeficiency virus Type 1 (HIV-1), hepatitis C virus (HCV), and hepatitis B virus (HBV) were 1:97,000, 1:490,000, and 1:2800, respectively. Several occult HBV donors, the majority of whom were detected by both tests, were also identified. The HIV-1 and HCV window cases were detected with both tests.

CONCLUSION

The performances of the systems and tests indicated that both were acceptable for routine NAT by the National Blood Center, the Thai Red Cross Society. However, the Procleix Ultrio test appeared to be less sensitive than the cobas TaqScreen test for HBV.

A novel diagnostic target in the hepatitis C virus genome

BACKGROUND

Detection and quantification of hepatitis C virus (HCV) RNA is integral to diagnostic and therapeutic regimens. All molecular assays target the viral 5'-noncoding region (5'-NCR), and all show genotype-dependent variation of sensitivities and viral load results. Non-western HCV genotypes have been under-represented in evaluation studies. An alternative diagnostic target region within the HCV genome could facilitate a new generation of assays.

METHODS AND FINDINGS

In this study we determined by de novo sequencing that the 3'-X-tail element, characterized significantly later than the rest of the genome, is highly conserved across genotypes. To prove its clinical utility as a molecular diagnostic target, a prototype qualitative and quantitative test was developed and evaluated multicentrically on a large and complete panel of 725 clinical plasma samples, covering HCV genotypes 1-6, from four continents (Germany, UK, Brazil, South Africa, Singapore). To our knowledge, this is the most diversified and comprehensive panel of clinical and genotype specimens used in HCV nucleic acid testing (NAT) validation to date. The lower limit of detection (LOD) was 18.4 IU/ml (95% confidence interval, 15.3-24.1 IU/ml), suggesting applicability in donor blood screening. The upper LOD exceeded 10(-9) IU/ml, facilitating viral load monitoring within a wide dynamic range. In 598 genotyped samples, quantified by Bayer VERSANT 3.0 branched DNA (bDNA), X-tail-based viral loads were highly concordant with bDNA for all genotypes. Correlation coefficients between bDNA and X-tail NAT, for genotypes 1-6, were: 0.92, 0.85, 0.95, 0.91, 0.95, and 0.96, respectively; X-tail-based viral loads deviated by more than 0.5 log10 from 5'-NCR-based viral loads in only 12% of samples (maximum deviation, 0.85 log10). The successful introduction of X-tail NAT in a Brazilian laboratory confirmed the practical stability and robustness of the X-tail-based protocol. The assay was implemented at low reaction costs (US$8.70 per sample), short turnover times (2.5 h for up to 96 samples), and without technical difficulties.

CONCLUSION

This study indicates a way to fundamentally improve HCV viral load monitoring and infection screening. Our prototype assay can serve as a template for a new generation of viral load assays. Additionally, to our knowledge this study provides the first open protocol to permit industry-grade HCV detection and quantification in resource-limited settings.

Three-dimensional array-based group testing algorithms

We derive the operating characteristics of three-dimensional array-based testing algorithms for case identification in the presence of testing error. The operating characteristics investigated include efficiency (i.e., expected number of tests per specimen) and error rates (e.g., sensitivity, specificity, positive, and negative predictive values). The methods are illustrated by comparing the proposed algorithms with previously studied hierarchical and two-dimensional array algorithms for detecting recent HIV infections in North Carolina. Our results indicate that three-dimensional array-based algorithms can be more efficient and accurate than previously proposed algorithms in settings with test error and low prevalence.

Estimating the pathogen safety of manufactured human plasma products: application to fibrin sealants and to thrombin

BACKGROUND

Plasma fractionators have implemented many improvements over the past decade directed toward reducing the likelihood of pathogen transmission by purified blood products, yet little has been published attempting to assess the overall impact of these improvements on the probability of safety of the final product.

STUDY DESIGN AND METHODS

Safety margins for human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV), hepatitis A virus (HAV), parvovirus B19, and variant form of Creutzfeldt-Jakob disease (vCJD) were calculated for the two fibrin sealants licensed in the United States and for thrombin. These products were selected because their use in a clinical setting is, in most cases, optional, and both were relatively recently approved for marketing by the US Food and Drug Administration (FDA). Moreover, thrombin and fibrinogen both undergo two dedicated virus inactivation steps and/or removal steps in accord with the recommendations of regulatory agencies worldwide. Safety margins were determined by comparing the potential maximum viral loads in contaminated units to viral clearance factors, ultimately leading to the calculation of the residual risk per vial.

RESULTS

The residual risk of pathogen transmission per vial was calculated to be less than 1 in 10(-15) for HIV, HCV, HBV, and HAV for both fibrinogen and thrombin. Owing to the greater quantities that can be present and its greater thermal stability, the calculated risk for parvovirus transmission was 1 in 500,000 vials for fibrinogen and less than 1 in 10(7) per vial for thrombin. Assuming that vCJD is found to be present in plasma donations, its risk of transmission by these purified and processed plasma derivatives would appear to be very low.

CONCLUSIONS

The pathogen safety initiatives implemented by plasma fractionators over the past 10 to 20 years have resulted in products with excellent pathogen safety profiles. Of the agents examined, parvovirus continues to have the lowest calculated margin of safety. Despite this, parvovirus transmissions should be rare. Manufacturers are encouraged to continue exploring processes to further enlarge parvovirus safety margins and to continue exploring ways of eliminating prions.

A general change of the platelet transfusion policy from apheresis platelet concentrates to pooled platelet concentrates is associated with a sharp increase in donor exposure and infection rates

BACKGROUND

We compare the actual with the potential donor exposure and possible infection rates in the Hanover Medical School (MHH) platelet (PLT) transfusion recipients if the current MHH standard of apheresis PLT concentrate (A-PC) supply would be replaced by a pooled PLT concentrate (P-PC) transfusion regimen.

DONORS PATIENTS AND METHODS

The electronic records of the MHH Institute of Transfusion Medicine and the MHH Department of Medical Controlling were evaluated to assess the development of PLT needs and supply at MHH from 2003-2006. For 2006, we evaluated all PLT transfusion recipients with respect to their overall transfusion needs, classified them for low and high PLT transfusion needs, and related them to the diagnostic groups that underlie their PLT demands. We assumed a P-PC preparation procedure using 4 whole blood-derived buffy coats for all calculations for potential donor exposure. To predict the possible infection rates of an unrecognized viral infection with low prevalence in the general population to A-PC or to P-PC recipients and the influence of neutralizing agent specific antibodies (NAB), we established a mathematical contamination/infection model based on the current PLT transfusion mode and data about GBV-C virus infection among Hanover blood donors.

RESULTS

From 2003 to 2006, the 1,300-1,400 persons comprising MHH apheresis donor pool covered a 36% increase in PC transfusions. The exclusive use of P-PCs instead of A-PC would require a total of 36,240-49,276 whole blood donations to meet MHH demands, corresponding to a more than 1 log step increase in donor exposure. For individual hematological patients, the change to P-PCs would imply an 80-125%, for individual surgical patients a 40-50% higher donor exposure. Our infection model revealed an approximately 4 times higher infection.

CONCLUSIONS

A change to P-PC would imply a more than one log step higher donor exposure, and an unrecognized infection with a prevalence around 1% leads to an up to 4 times higher infection rate. A general change in the PC transfusion policy that favors P-PCs is dangerous and must be avoided.

Blood screening for influenza

Influenza viruses, including highly pathogenic avian influenza virus (H5N1), could threaten blood safety. We analyzed 10,272 blood donor samples with a minipool nucleic acid amplication technique. Analytical sensitivity of the method was 804 geq/mL and 444 geq/mL for generic influenza primers and influenza (H5N1) subtype–specific primers. This study demonstrates that such screening for influenza viruses is feasible.

Efficacy and Adverse Events of Platelet Transfusion Product-Specific Differences

SUMMARY: TWO PREPARATIONS ARE AVAILABLE FOR PLATELET TRANSFUSION: single-donor apheresis platelet concentrates (APC) and pooled platelet concentrates (PPC) prepared from 4-6 whole blood units. Clear advantages of APC over PPC are a markedly reduced donor exposure of recipients, and easier logistics when attempting a complete supply with ABO-identical and Rh-compatible platelet concentrates. Regulations should aim at complete ABO-identical platelet transfusions because major and minor ABO-incompatible platelet transfusions are probably associated with significantly increased morbidity and mortality. The main advantage of PPC is lower costs. Preparation of PPC is however inevitably accompanied by substantial wastage of plasma and red cells. Only major supraregional blood transfusion centers can guarantee full-coverage supply with ABO-identical and Rh-compatible PPC. Whether APC are more effective than PPC and associated with fewer septic platelet transfusion reactions as shown in some but not all studies, has to be examined in future prospective controlled trials.

Detection of HIV-1 infection in blood donors during the immunological window period using the nucleic acid-amplification technology

Individual nucleic acid-amplification testing (NAT) was recently recommended by Brazilian legislation and has been implemented at some blood banks in the city of São Paulo, Brazil, in an attempt to reduce the transfusion transmission of human immunodeficiency virus (HIV) and hepatitis C viruses. This screening test can identify donations made during the immunological window period before seroconversion. The impact of this technology in our blood donors and transfusion routine was studied. In all, 47 866 donations were tested from March 2004 until November 2005, according to Brazilian legislation, using two approved enzyme immunoassays for HIV antibodies and individual NAT. Supplemental tests included Western blot, p24 antigen detection and quantitative PCR-HIV-1. Among the donors screened, two (one first-time and one repeat donor) were non-reactive in enzyme immunoassays, with negative confirmatory p24 antigen and Western blot, but positive for HIV-1 NAT. Although serological analysis for HIV is a primary tool for diagnostic testing, the addition of NAT allowed for identification and prevention of component transfusion from two HIV-positive blood donations during an 18-month period. The screening of donors reduced the immunological window period, permitting the identification of very early stage HIV infections. In addition, this report also emphasized the fact that the risk of HIV transmission is not limited to the first-time donors.

Routine HIV screening among blood donors in Buenos Aires (Argentina): results from six years' experience and report of a single window-period donation

BACKGROUND

Blood donor HIV antibody detection has been mandatory in Argentina since 1991, and p24 antigen screening was recommended in 1997.

METHODS

A total of 30,132 consecutive donations were screened. Repeatedly reactive samples were tested by another screening test and/or by Western blot (WB) for HIV Ab, or by a neutralization assay for p24 Ag.

RESULTS

Among the total, 0.3623% of samples were repeatedly reactive and 0.2084% were true HIV-infected donors. Only one donor tested nonreactive for HIV Ab, repeatedly reactive for p24 Ag, positive by neutralization assay, and seroconverted later. Samples with a signal-to-cutoff (S/CO) ratio >/= 3.00 on routine HIV Ab testing were 100.0% positive by WB and/or repeatedly reactive by the second test. In samples with a S/CO ratio < 3.00, 11.1% were positive by WB and/or the majority were nonreactive by the second test. Among HIV-infected donors, 89.5% possessed risk factors (which had been denied previously), 56.5% were repeatedly reactive by other screening procedures and 88.6% were coinfected with other blood-transmissible viruses.

CONCLUSIONS

When the EIA S/CO ratio is >/= 3.00, WB can be replaced by a second screening test. The pre-donation questionnaire should be improved to detect risk behavior in prospective donors. There was a high association between HIV and other blood-transmissible viruses.

Twenty-four mini-pool HCV RNA screening outside a blood transfusion setting: Results of a 2-year prospective study

The usefulness of 24 mini-pool hepatitis C virus (HCV) RNA screening was evaluated in a 2-year prospective study carried out on a total of 6432 consecutive anti-HCV negative specimens in a routine diagnostic laboratory setting. A total of 268 mini-pools were tested using an automated commercial PCR assay for qualitative detection of HCV RNA, with a lower limit of detection of 50 IU/ml. Eighteen (0.28%) anti-HCV negative/HCV RNA positive serum samples obtained from 12 patients (all intravenous drug users), were detected. Ten patients responded to an invitation for follow-up testing. Five, three and one patient seroconverted in the first, second and third follow-up sample, respectively. One patient had not seroconverted by the end of the study period. The interval between the first HCV RNA positive sample and the first anti-HCV positive samples was 24-192 days. The costs of detecting a single anti-HCV negative/HCV RNA positive sample and a single anti-HCV negative/HCV RNA positive patient using the 24 mini-pool HCV RNA screening strategy were estimated to be around euro 643 and 965, respectively. It was shown that screening for HCV infection using the 24 mini-pool HCV RNA screening strategy can also be both useful and cost effective outside a blood transfusion setting.

Comparison of three bacterial detection methods under routine conditions

BACKGROUND AND OBJECTIVES

Since 2004, bacterial screening of platelets has been required in the USA and is also done on a voluntary basis in many European countries. The German Red Cross blood donor services conducted a prospective multicentre study in order to investigate the prevalence of bacterially contaminated pool platelet concentrates and apheresis platelet concentrates. This substudy compares three different bacterial detection systems.

STUDY DESIGN AND METHODS

Platelet concentrates were tested in parallel with BacT/ALERT, Scansystem and Pall eBDS (n = 6307) in pool platelets. Apheresis platelets were tested in parallel with BacT/ALERT and Pall eBDS (n = 4730). All initially positive results were evaluated by a standardized procedure including evaluation by a microbiology reference laboratory.

RESULTS

One in 6307 pool platelets were confirmed positive by BacT/ALERT, whereas Pall eBDS and Scansystem failed to detect these samples. Only three samples were initially reactive with Pall eBDS without proof of any bacteria strains. The rate of false-positive results was substantially higher for BacT/ALERT (0.25%, 28 in 11,037 tested samples) than for eBDS (0.03%, 3 in 11 037 tested samples) or Scansystem (0.0%, 0 in 6307 tested samples). Three of 4730 apheresis platelets were confirmed positive by BacT/ALERT. These were negative with Pall eBDS.

CONCLUSION

Sensitivity was best for BacT/ALERT, whereas specificity was enhanced for Pall eBDS and Scansystem. Scansystem required specially trained staff, whereas BacT/ALERT and Pall eBDS were easy, quick, user-friendly and objective methods.

Characterization of HBV DNA+/HBsAg- blood donors in Poland identified by triplex NAT

Nucleic acid testing (NAT) for hepatitis B virus (HBV) has been performed in Poland since 2005 on samples seronegative for hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (anti-HCV), and anti-human immunodeficiency virus (anti-HIV). Tools included 24-donation pool testing (PT) using Cobas Amplicor or in individual donations (ID) by Procleix Ultrio. Seven of 761,666 (1:108,800) and 21/250,191 (1:11,900) HBV DNA-positive donations were identified and confirmed by alternative methods. HBV DNA load ranged between 11.6 and 4.6 x 10(4) IU/mL in 11 samples and could not be quantified in 17 samples. HBV genotypes A (56%) and D (4%) were found. The analysis of combined results from index, follow-up, and look-back samples identified four groups: (1) Two cases tested HBsAg positive with alternative, more sensitive, assays; (2) Four cases were in the pre-seroconversion window period; (3) Eight cases had a fluctuating pattern of HBV DNA and anti-HBs detection (recovered infection); and (4) twelve cases carried anti-HBc without anti-HBs, which might correspond to either chronic or recovered "occult" HBV infection. One donor with no HBV markers in the follow-up was excluded, and another was in the window period preceding anti-HBs. HBV NAT identified more confirmed positive donors than HCV or HIV NAT, and 1:250,000 could not be detected by anti-HBc screening. Serological and molecular studies on follow-up and look-back samples are important to classify donors. In conclusion, further studies are needed to determine whether the considerably higher yield of HBV DNA detection obtained with individual donation screening improves blood safety compared with anti-HBc screening.

High throughput screening for spores and vegetative forms of pathogenic B. anthracis by an internally controlled real-time PCR assay with automated DNA preparation

Human infections with Bacillus anthracis have become rare but in cases of intentional release, masses of samples would have to be expected. Current PCR assays for anthrax are appropriate for use in single cases, but they have not been formulated for high throughput screening. This article describes a high throughput real-time PCR for anthrax, including automated sample preparation without the need for pre-culturing of samples. The assay detects single copies of target gene. An internal control monitors the whole assay including sample preparation. The limit of detection in blood was 1,066 (95%CI, 741-1,739) copies/ml, corresponding to 4.4-32.3 organisms/ml. Using spore preparations, 20 colony-forming units (CFU) per sample could be detected reliably (0.8 CFU per PCR). The extraction procedures depleted viable spores from solution by factors of 10,000 (automated procedure) and >100,000 (conventional column procedure). One hundred and ten clinical and environmental specimens were retested, 50 of them sampled during a period of heightened anthrax awareness in 2001. A widely used assay yielded two false positive results (cross-reaction with B. cereus), while the new assay tested all samples negative. The internal control operated stable in all clinical samples. The assay is capable of testing for anthrax in the high throughput mode.

Estimation of the prevalence of lymphatic filariasis by a pool screen PCR assay using blood spots collected on filter paper

The prevalence of lymphatic filariasis was estimated by PCR-based pool screening of night blood collected from 865 individuals living in ten areas endemic for Wuchereria bancrofti, Brugia malayi or B. timori in Indonesia. A total of 232 microfilaraemics were identified by filtration of 1 ml of blood. The microfilaria (mf) prevalence ranged from 6% to 54%, and the mf density in microfilaraemics ranged from 1 mf/ml to 6028 mf/ml. PCR assays both for W. bancrofti or Brugia spp. detected a single mf present on a 30 microl dried filter paper blood spot. One hundred and seventy-eight pools of five blood spots in each pool (pool-5) were tested by PCR and 101 (57%) pools were positive. When pool size was increased to 10 spots per pool (pool-10), 65 (70%) of 93 pools were positive. Pearson's correlation and linear regression showed a strong correlation between filtration and pool screen PCR results for pool-10 (r=0.835) and pool-5 (r=0.695). Based on the determination coefficient (R), the results of pool-10 PCR (R=0.697) gave a better prediction compared with pool-5 PCR (R=0.483). This study suggests that pool screen PCR may be a useful tool for monitoring the Global Program to Eliminate Lymphatic Filariasis.

The natural history of hepatitis C virus (HCV) infection

Hepatitis C virus (HCV) is a leading cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma, as well as the most common indication for liver transplantation in many countries. Although the incidence of hepatitis C infection has dramatically decreased during the past decade, the worldwide reservoir of chronically infected persons is estimated at 170 million, or 3% of the global population. There is much controversy surrounding the natural history of hepatitis C infection. The rate of chronic HCV infection is affected by a person's age, gender, race, and viral immune response. Approximately 75%-85% of HCV-infected persons will progress to chronic HCV infection, and are at risk for the development of extrahepatic manifestations, compensated and decompensated cirrhosis, and hepatocellular carcinoma (HCC). The rate of progression to cirrhosis is highly variable, and is influenced by several factors, including the amount of alcohol consumption, age of initial HCV infection, degree of inflammation and fibrosis on liver biopsy, HIV and HBV coinfection, and comordid conditions. An estimated 10%-15% of HCV-infected persons will advance to cirrhosis within the first 20 years. Persons with cirrhosis are at increased risk of developing HCC. An understanding of the natural history of hepatitis C is essential to effectively manage, treat, and counsel individuals with HCV infection.

Is an assay for simultaneous detection of hepatitis C virus core antigen and antibody a valuable alternative to nucleic acid testing?

BACKGROUND

A new enzyme immunoassay based on the simultaneous detection of nucleocapsid proteins of hepatitis C virus (HCV) and anti-HCV (Monolisa HCV antigen-antibody Ultra, Bio-Rad) was evaluated as an alternative to nucleic acid testing (NAT) for the diagnosis of HCV infection during the window period in blood donations.

STUDY DESIGN AND METHODS

The study included 107 sequential samples from 10 HCV seroconversion commercial panels; 81 samples were in the preseroconversion phase, and 26 were collected after seroconversion. All samples were tested with HCV antigen-antibody assay and the two minipool (MP) NAT procedures that are routinely used in France (transcription-mediated amplification in pools of 8 and COBAS AmpliScreen HCV test [Roche Diagnostic] in pools of 24 donations).

RESULTS

From the 44 samples collected during window period that were MP-NAT-positive, 31 (70.5%) were also positive with the Monolisa HCV antigen-antibody assay. The mean delay in detecting HCV infection between these two methods was 5.1 days (range, 0-24 days). The Monolisa HCV antigen-antibody assay led to a reduction in the window period of 26.8 days (range, 0-72 days). All samples collected after seroconversion were detected with the HCV antigen-antibody assay. The specificity analyzed in 2503 consecutive blood donations was estimated at 99.88 percent.

CONCLUSION

This new developed assay presents an improvement for the detection of HCV infection, especially in the early phase of infection when antibodies are undetectable. Although less sensitive than NAT, this assay could be a suitable solution for blood screening in developing countries where NAT (or HCV core antigen-specific assay) is not affordable or its implementation is not feasible.