Second hepatitis C virus transmission by blood components since introduction of mandatory NAT screening in Germany

BACKGROUND

Viral safety of blood products in Germany has improved significantly over the last two decades. We describe the second documented transfusion-transmitted (TT) episode for the hepatitis C virus (HCV) in Germany since mandatory nucleic acid amplification techniques (NAT) screening was introduced in 1999.

STUDY DESIGN AND METHODS

When a repeat donor who had tested negative for anti-HCV tested positive for HCV RNA by NAT in a minipool (MP) of eight, a look-back procedure was initiated. Qualitative, quantitative and genotyping assays were used to investigate the titers of the quarantined fresh frozen plasma (FFP) from the donor and a serum sample from the recipient of the pooled platelet concentrate (PPC). Amplified products of 5'UTR and HVR1 were used for sequence comparison to characterize the HCV genomic identity of donor and recipient samples.

RESULTS

All NAT tests utilized in this procedure were able to detect a low HCV RNA titer (~15 IU/ml) in the FFP from the donation. Dilution of FFP by factor 8 was performed to mimic an MP, and the detection rate correlated well with the claimed sensitivity of the tests. Analysis of donor and recipient samples revealed genotype 3a viral transmission confirmed by sequence analysis.

CONCLUSION

This TT HCV case could have been prevented by individual donation (ID) NAT. However, a low titer blood donation in the window period (WP) is very rare. Residual risk calculation for TT HCV in the WP revealed that, compared to MP-NAT testing, ID-NAT would improve blood safety only marginally.

Reliable quantification of plasma HDV RNA is of paramount importance for treatment monitoring: A European multicenter study

OBJECTIVES

Quantification of plasma hepatitis D virus (HDV) RNA is the essential tool for patient management under antiviral therapy. The aim of this European multicenter study was to improve the comparability of quantitative results reported by different laboratories using the CE/IVD-labeled RoboGene HDV RNA Quantification Kit 2.0 (Roboscreen GmbH) with different manual or automated nucleic acid extraction protocols/platforms and amplification/detection devices.

METHODS

For harmonization of HDV RNA concentrations obtained by different protocols, correction factors (CF) were determined using the 1st WHO International Standard for HDV RNA. The limit of detection (LOD) and accuracy were determined for each protocol by using reference material. Furthermore, clinical samples were analyzed and results compared.

RESULTS

The CF ranged from 20 to 1,870 depending on the protocol used. The LOD was found between 4 and 450 IU/ml. When accuracy was tested, external quality control (EQC) samples containing low HDV RNA concentrations were not detected by those protocols with higher LODs. For EQC samples, the maximum standard deviation of HDV RNA concentrations was found to be 0.53 log₁₀ IU/ml, for clinical samples 0.87 log₁₀ IU/mL.

CONCLUSION

To ensure reliability in quantification of HDV RNA, any modification of the extraction and amplification/detection protocol validated by the manufacturer requires revalidation. With the 1st WHO International Standard for HDV RNA, the CF could easily be calculated leading to harmonization of quantitative results. This warrants both accurate monitoring of response to existing anti-HDV treatment and comparability of study results investigating novel anti-HDV drugs.

Detection of hepatitis C virus and parvovirus B19 in human plasma pools by nucleic-acid amplification techniques - Trends in results of EDQM proficiency testing studies from 2004 to 2018

The European Directorate for the Quality of Medicines & HealthCare (EDQM) has run proficiency testing schemes on the detection of viral contaminants in human plasma pools by nucleic-acid amplification techniques since 1999 for hepatitis C virus and since 2004 for parvovirus B19. A retrospective analysis was performed to assess their impact and identify trends and progress in the results obtained by participating laboratories over a 15-year span, from 2004 to 2018. The results demonstrate that overall performance improved over that time, especially among the regular participants. Participation in these proficiency testing schemes is therefore recommended for all interested control laboratories. This analysis also shows that hepatitis C virus detection now seems well established compared to that of parvovirus B19, which still appears more challenging.

Reliability of CE-marked NATs for HIV-1 subtype C detection and quantitation

We compared seven CE-marked HIV-1 RNA nucleic acid amplification technology (NAT) based assays for their detection efficiency and quantitation concordance in regard to HIV-1 subtype C. We used 398 plasma samples from South African repeat blood donors identified as HIV positive at occasion of routine screening NAT performed mainly during the years 2010-2013, with most plasma samples reflecting recent HIV-1 infections. All HIV-1 subtype C specimens were detected, independent of mono- or dual-target assay design. In the same time period new variants of HIV-1 subtype B had been identified which were missed by some mono-target assays, a finding which was not corroborated for subtype C in our study. A high level of concordance of HIV-1 subtype C quantitation was determined for the HIV-1 NATs, showing successful standardization in this diagnostic field.

On the rapid in situ oxidation of two-dimensional V2CTz MXene in culture cell media and their cytotoxicity

The plethora of emerging two-dimensional (2D) materials exhibit wide potential application in novel technologies and advanced devices. However, their stability in environmental conditions could be an issue, affecting their application possibilities and posing health risks. Moreover, their decomposed leftovers can also induce a negative influence on human health. In particular, transition metal carbides commonly referred to as MXenes are susceptible to environmental oxidation being decomposed toward transition metal oxides and carbide-derived carbon. In this study we focused on the oxidation-state-related in vitro cytotoxicity of delaminated V₂CT_z onto immortalized keratinocytes (HaCaT) and malignant melanoma (A375) human cell lines. Due to the fact, that the V₂CT_x MXenes are least stable from all known obtained MXenes up to date, the vanadium ones were a practical choice to visualize the oxidation-cytotoxic correlation keeping the standards of 24-48 h of cell culturing. We found that the oxidation of V₂CT_z highly increases their cytotoxicity toward human cells, which is also time and dose dependent. The identified mode of action relates to the cell cycle as well as cellular membrane disintegration through direct physicochemical interactions.

Immunoreactivity pattern of monoclonal antibodies against Hepatitis B vaccine with global Hepatitis B virus genotypes

Hepatitis B surface antigen (HBsAg) specific monoclonal antibodies (mAbs) are potentially valuable therapeutic and diagnostic tool. We have previously established and characterized a panel of mAbs derived from immunized BALB/c mice with a yeast-derived recombinant HB vaccine subgentoype A2 and HBsAg subtype adw2. This study was conducted to evaluate the reactivity pattern of this anti-HBs mAbs panel with various genotypes and subgenotypes of HBV using the first WHO HBV genotype reference panel containing 15 serum samples representing the subgenotypes A1, A2, B1, B2, C2, D1-D3, E, F2, and H. Ten out of 21 anti-HBs mAbs were able to strongly recognize all gentopye/subtypes of HBsAg provided in the WHO reference panel. However, 10 out of 21 anti-HBs mAbs showed a moderate to profound loss of reactivity with HBV genotypes/HBsAg subtypes D2/ayw3, E/ayw4, F2/adw4, and H/adw4. Two mAbs from the second group displayed a profoundly reduced reactivity with only 1 out of 3 C2/adr genotype/subtype samples. The amino acid alignment of these 3 samples showed that this particular sample contains amino acid substitution at residue 127, which is located inside "a" determinant. This amino acid substitution, which profoundly affected the reactivity of anti-HBs antibodies, has been previously reported only in D/ayw3, E/ayw4, F/adw4, and H. Interestingly, the amino acid alignment of the samples in this WHO panel showed that P127T substitution can also be found in C2/adr. Comparing amino acids sequences inside the antigenic loop (AGL) showed that D2/ayw3 contains a T118A/P127T double substitution, E/ayw4 contains P127L/T140S, F2/adw4 contains P127L/T140S/ F158L, and H/adw4 contains P127L substitution. Therefore, amino acid variability at positions 118, 127, 140, and 158 was found to cause significant loss of reactivity with anti-HBs mAbs. Since HBsAg variability in different genotypes of HBV can profoundly affect the reactivity of anti-HBs mAbs, analytical sensitivity for HBsAg assays should be considered based on the circulating and common HBV variants in the relevant countries.

A simple, low-cost and green method for controlling the cytotoxicity of MXenes

MXene phases are a member of the intriguing 2D material family, beyond graphene. They are good candidates for many applications, however, their potential toxicity is of crucial importance for future development. Herein, we present a simple, low-cost and fully green approach for controlling the potential cytotoxicity of 2D MXenes after delamination by harnessing the interactions that occur between the surface of MXene phases and natural biomacromolecule - collagen. We also demonstrate that the step-by-step adsorption and desorption of collagen from the surface of 2D MXenes is easily controlled using in situ zeta potential measurements coupled with dynamic light scattering (DLS) method. The obtained results demonstrated that the electrostatically driven unprecedented susceptibility of the MXenes' surfaces to collagen. Surface-modification reduces toxicity of MXenes in vitro i.e. adjust cells' viabilities as well as reduce their oxidative stress. This indicates enhanced biocompatibility of 2D Ti₃C₂ and Ti₂C MXenes surface-modified with collagen, which is involved in many bio-interactions as important building blocks in the human body. The presented study opens new avenues for designing MXenes with defined surface properties and paves the way for their future successful management in nano-medicinal applications.

Detection of hepatitis B virus infection in German blood donors 2008-2015

BACKGROUND AND OBJECTIVES

Assessment of HBV-NAT testing compared to HBsAg and anti-HBc screening in German blood establishments for the period 2008-2015.

MATERIALS AND METHODS

Blood donations screened for HBsAg and anti-HBc along with HBV-NAT were evaluated. Sensitivity of HBsAg and HBV-NAT tests was compared in 30 HBV seroconversion panels and with the viral load of the NAT-only cases. Residual risk for HBV in the WP was modelled.

RESULTS

A total of 45 270 111 donations were evaluated. There were 29 NAT-only cases in the HBsAg-negative HBV-WP, one by ID-NAT and 28 by MP-NAT. MP-NAT, on average, showed higher sensitivity than HBsAg testing: MP-NAT-LoD of 146 IU/ml vs. 362 IU/ml HBV DNA for positive HBsAg detection (range 135-1502 IU/ml), resulting in 3·1 days (range 2·0-4·8 days) earlier HBV detection. Viral loads of the NAT-only cases confirmed the sensitivity of the HBV tests in the seroconversion study. One HBsAg-negative case was due to a new HBsAg mutant combination. There was one HBsAg-reactive only case. In addition, HBV incidence in the HBV-WP included 41 HBsAg-/HBV-NAT-positives and three HBV transmission cases. The residual risk for HBsAg was estimated to be 1:1 619 419-1 268 474 compared to 1:2 793 365-2 134 702 for MP-NAT. Within chronic HBV (HBsAg-/anti-HBc-positive and MP-NAT-negative) 70% were ID-NAT positive at low viral load (median 20 IU/ml). Among anti-HBc-only, supplementary ID-NAT detected 23 occult HBV infections.

CONCLUSIONS

In the HBV-WP, MP-NAT provided a higher sensitivity than HBsAg testing, obtained a considerably higher yield and reduced the risk for HBV transmission. In later HBV stages, anti-HBc screening and HBV-ID-NAT intercepted potentially infectious donations.

Multilayered stable 2D nano-sheets of Ti2NTx MXene: synthesis, characterization, and anticancer activity

BACKGROUND

The biological activity of MXenes has been studied for several years because of their potential biomedical applications; however, investigations have so far been limited to 2D titanium carbides. Although monolayered Ti2NTx MXene has been expected to have biological activity, experimental studies revealed significant difficulties due to obstacles to its synthesis, its low stability and its susceptibility to oxidation and decomposition.

RESULTS

In this paper, we report our theoretical calculations showing the higher likelihood of forming multilayered Ti2NTx structures during the preparation process in comparison to single-layered structures. As a result of our experimental work, we successfully synthesized multilayered Ti2NTx MXene that was suitable for biological studies by the etching of the Ti2AlN MAX phase and further delamination. The biocompatibility of Ti2NTx MXene was evaluated in vitro towards human skin malignant melanoma cells, human immortalized keratinocytes, human breast cancer cells, and normal human mammary epithelial cells. Additionally, the potential mode of action of 2D Ti2NTx was investigated using reactive oxygen tests as well as SEM observations. Our results indicated that multilayered 2D sheets of Ti2NTx showed higher toxicity towards cancerous cell lines in comparison to normal ones. The decrease in cell viabilities was dose-dependent. The generation of reactive oxygen species as well as the internalization of the 2D sheets play a decisive role in the mechanisms of toxicity.

CONCLUSIONS

We have shown that 2D Ti2NTx in the form of multilayered nanoflakes exhibits fair stability and can be used for in vitro studies. These results show promise for its future applications in biotechnology and nanomedicine.

Effectiveness of blood donor screening by HIV, HCV, HBV-NAT assays, as well as HBsAg and anti-HBc immunoassays in Germany (2008-2015)

Background and Objectives

In Germany, in addition to standard blood donor screening, further mandatory tests were introduced for HCV‐RNA, HIV‐1‐RNA and for anti‐HBc. Screening for HBV‐DNA is optional. This study investigates the benefits of these additional tests for the detection of HIV, HCV, and HBV infections among German blood donors.

Materials and Methods

From 2008 to 2015 we collected data on blood donations exclusively testing NAT positive (NAT yield) or reactive in only one of the screening assays. Assuming a Poisson distribution, we calculated NAT yield/reactive only rates on a per donation basis (number of yield/reactive only cases divided by the number of donations tested in the period under review) with 95% confidence intervals.

Results

Responding establishments covered 95% of the donations. We identified 20 HIV‐1‐NAT, 61 HCV‐NAT and 29 HBV‐NAT yield cases among approximately 46 million blood donations tested corresponding to 0·43 HIV‐1 NAT, 1·32 HCV‐NAT, and 0·64 HBV‐NAT yield cases per million blood donations tested. For one HBsAg reactive only case and 23 anti‐HBc reactive only cases in repeat donors, infection was confirmed by ID‐NAT which translates into 0·02 and 0·55 cases per million donations tested. During the 8‐year‐observation period, one HIV‐1, no HCV and four HBV transmissions associated with donations in the viremic pre‐seroconversion window period were reported.

Conclusion

Annually, NAT screening alone detected 2·5 HIV‐1, 7·6 HCV, and 3·6 HBV infectious donations; anti‐HBc screening alone identified 2·9 infectious donations of repeat donors with occult HBV infection. Overall, the survey results support that the currently practiced donor HIV/HCV/HBV screening strategy in Germany does ensure a high standard of blood safety.

Impact of hepatitis E virus testing on the safety of blood components in Germany - results of a simulation study

Hepatitis E virus (HEV) infections may be acquired through transfusion of blood components. As transfusion-transmitted infections mostly affect vulnerable individuals, measures to ensure the supply of safe blood components are under discussion. On the basis of the epidemiological situation in Germany, different testing strategy scenarios were investigated through simulation studies. Testing for HEV RNA by nucleic acid amplification technique (NAT) assays with a pool size of 96, and a 95% LoD of 20 IU/ml will result in an 80% reduction in expected HEV transmissions as well as of consequent chronic infections with subsequent severe complications.

Virusübertragungen durch Blutprodukte: Mögliche Ursachen und Konsequenzen

Die Sicherheit von Blutund Blutprodukten hat in den letzten Jahren aufgrund der Übertragung von Viren, insbesondere von Humanen Immundefizienz-Viren (HIV), zunehmend Beachtung gefunden. Das Risiko der Virusübertragung konnte durch Einführung entsprechender Testverfahren deutlich reduziert werden. Vor allem die Herstellung von Blutderivaten ist durch Einführung von Virusinaktivierungsmaßnahmen seitens der pharmazeutischen Industrie sicherer geworden. Trotz dieser Maßnahmen sind allerdings noch Virusübertragungen durch Blutprodukte aufgetreten. Das Paul-Ehrlich-Institut als die für die Zulassung von Blutzubereitungen zuständige Bundesoberbehörde hat die gemeldeten Fälle untersucht. Als Konsequenz wurden die Einführung von zwei unterschiedlichen Virusinaktivierungsschritten mit einer Virusreduktion von jeweils etwa 4 log-Stufen und das Erzielen einer Gesamtreduktion in der Größenordnung von 1010 für lipidumhüllte Viren gefordert.

Blood donor screening for West Nile virus (WNV) revealed acute Usutu virus (USUV) infection, Germany, September 2016

Between 1 June and 31 December 2016, 13,023 blood donations from the University Hospital Aachen in Germany were routinely screened for West Nile virus (WNV) RNA using the cobas TaqScreen WNV Test. On 28 September 2016, one blood donor was tested positive. Subsequent analysis revealed an acute Usutu virus (USUV) infection. During the ongoing USUV epizootics in Germany, blood transfusion services, public health authorities and clinicians should be aware of increased human USUV infections.

In vitro studies on cytotoxicity of delaminated Ti3C2 MXene

MXenes are a novel family of 2D materials, the biological activity of which has been largely unexplored. The present study, for the first time, shows some aspects of the in vitro toxicity of 2D sheets of Ti₃C₂ MXene. The Ti₃AlC₂ MAX phase was used in an expansion and delamination process to obtain Ti₃C₂ material in the form of 2D sheets. The obtained 2D material was characterized using SEM, TEM, DLS, XPS, and zeta potential. The biological activity of the MXene was determined on two normal (MRC-5 and HaCaT) and two cancerous (A549 and A375) cell lines. The cytotoxicity results indicated that the observed toxic effects were higher against cancerous cells compared to normal ones. The mechanisms of potential toxicity were also elucidated. It was shown that MXene may affect the occurrence of oxidative stress and, in consequence, the generation of reactive oxygen species (ROS). The results of the present study provide the principal knowledge to date regarding the biological activity of the MXenes; the lack of such knowledge is the major obstacle on the MXenes' road to further research and development on their applications in bioscience and biotechnology, e.g. as drug-delivery systems.

A549 and MRC-5 cell aggregation in a microfluidic Lab-on-a-chip system

In this paper, we present a culture of A549 and MRC-5 spheroids in a microfluidic system. The aim of our work was to develop a good lung cancer model for the evaluation of drug cytotoxicity. Our research was focused on determining the progress of cell aggregation depending on such factors as the depth of culture microwells in the microdevices, a different flow rate of the introduced cell suspensions, and the addition of collagen to cell suspensions. We showed that these factors had a significant influence on spheroid formation. It was found that both MRC-5 and A549 cells exhibited higher aggregation in 500 μm microwells. We also noticed that collagen needs to be added to A549 cells to form the spheroids. Optimizing the mentioned parameters allowed us to form 3D lung tissue models in the microfluidic system during the 10-day culture. This study indicates how important an appropriate selection of the specified parameters is (e.g., geometry of the microwells in the microsystem) to obtain the spheroids characterized by high viability in the microfluidic system.

Comparative characterization of hepatitis B virus surface antigen derived from different hepatitis B virus genotypes

For human hepatitis B virus eight distinct and two candidate genotypes are described. These genotypes differ with respect to geographic distribution, molecular virology and virus-associated pathogenesis. Comparative analysis of HBV genotypes revealed, with exception of HBV/G that shows impaired HBsAg release, that no fundamental disparities between genotypes exist regarding glycosylation, subcellular distribution, release of HBsAg and formation of subviral particles. However, there are distinctions regarding the proportion of L to M to S HBs proteins detected intra- and extracellularly for different genotypes. 2D electrophoresis revealed different posttranslational modification patterns for LHBs. In light of the relevance of HBsAg as diagnostic marker, detectability of purified recombinant HBsAg of various genotypes by HBsAg-specific detection systems licensed in Europe was investigated, showing similar sensitivities for genotypes included in this analysis. These data indicate that recombinant HBsAg reproducibly purified following a defined protocol might be used as an alternative to reference materials currently established.

Establishment of the Ph. Eur. Hepatitis A virus RNA for NAT testing BRP batch 1

Detection of viral contamination in plasma donations is critical to prevent transmission of infectious diseases. The European Pharmacopoeia (Ph. Eur.) monograph 1646 'Human plasma (pooled and treated for virus inactivation)', requires that plasma pools used for the manufacture of this product be tested, among others, for the presence of hepatitis A virus RNA by nucleic acid testing (NAT) using a positive control containing 100 International Units (IU) of hepatitis A virus (HAV) RNA per mL. To this end, the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe) organised an international collaborative study under the aegis of the Biological Standardisation Programme, for the establishment of the 1^st Biological Reference Preparation (BRP) for HAV RNA for NAT testing. A freeze-dried candidate material was thus prepared and calibrated against the WHO 2^nd International Standard for HAV for NAT (00/562) in a study in which thirteen European and North American laboratories including Official Medicines Control Laboratories (OMCLs), manufacturers of plasma-derived products, producers of in vitro diagnostic kits and a blood transfusion centre participated. Based on the outcome of the study, an HAV RNA content of 40 000 IU/vial (corresponding approximately to 4.6 log₁₀ IU/vial) was assigned to the BRP, which was adopted by the Ph. Eur. Commission in March 2016 as Ph. Eur. hepatitis A virus RNA for NAT testing BRP batch 1.

International collaborative study on the 3rd WHO International Standard for hepatitis B surface antigen

BACKGROUND

The WHO International Standard (IS) for hepatitis B surface antigen (HBsAg) is used to standardize HBsAg assays. Stocks of the 2nd IS for HBsAg are depleted. The proposal to establish its replacement was endorsed by WHO in 2012.

OBJECTIVE

Preparation of a freeze-dried candidate 3rd IS (NIBSC 12/226); evaluation of its suitability in a WHO international collaborative study; calibration of its potency in International Units (IU).

STUDY DESIGN

The 3rd IS is based on plasma-derived, purified, inactivated HBsAg from Vietnam. Qualitative and quantitative HBsAg assays were used to evaluate 12/226 alongside the 2nd IS and 1st IS. Blinded study samples included a duplicate of 12/226, a negative control and two diluted plasma samples representing hepatitis B virus (HBV) genotypes A and B.

RESULTS

Twelve laboratories from 9 countries returned 22 data sets from 15 methods. The overall geometric mean potency of 12/226 is 47.3IU/mL (±13% CV) when compared to the 2nd IS with HBV subgenotype A2. The 3rd IS has HBV subgenotype B4 with a heterogeneous HBsAg subtype population of ayw1 and adw2. Some genotype-dependent effects on the inter-laboratory variability were observed but overall mean potencies were virtually identical irrespective of the IS used for calibration. Stability studies indicate that the candidate is stable for long-term use.

CONCLUSIONS

12/226 was established in October 2014 by the WHO Expert Committee on Biological Standardization as the 3rd IS for HBsAg with a potency of 47.3IU per ampoule maintaining the continuity in the standardization of HBsAg assays.

Standardization of NAT for Blood-Borne Pathogens

Assays based on nucleic acid amplification technology (NAT) are increasingly used for screening of blood and for diagnosis or monitoring of patients. Both regulatory requirements for blood screening and international recommendations for the treatment of patients are based on common reference materials available globally for the standardization of NAT assays. World Health Organization International Standards (WHO ISs) and International Reference Panels (WHO IRPs) are primary reference materials. The characterization and manufacture of WHO reference materials as well as their evaluation is performed on behalf of the WHO by collaborating centers; their establishment is decided upon by the WHO Expert Committee on Biological Standardization (ECBS). The potency of the first WHO IS is defined by the 'international unit' (IU) which should be maintained upon replacement of the IS. The IU, unlike copy number or genome equivalent, is defined by the IS with a physical existence, is available worldwide, and allows traceability and comparability of results. The anticipated use of WHO ISs is the calibration of secondary standards or the validation of essential assay features, e.g. limit of detection.

Intracellular accumulation of subviral HBsAg particles and diminished Nrf2 activation in HBV genotype G expressing cells lead to an increased ROI level

BACKGROUND & AIMS

Hepatitis B virus genotype G (HBV/G) is characterized by a lack of HBeAg secretion and very low HBsAg secretion. This study aimed at (1) comparing HBV genotype G and A2 with respect to morphogenesis and release of HBV-derived particles, (2) characterizing factors contributing to HBV/G-associated pathogenesis.

METHODS

HBV/G- and HBV/A-expressing hepatoma cells and infected HepaRG cells were analyzed by confocal laser scanning microscopy, Western blot, real-time PCR, density gradient centrifugation, and electron microscopy. Modulation of the transcription factors Nrf2 and AP-1 was analyzed.

RESULTS

While the release of viral particles is not affected in HBV/G replicating cells, the secretion of subviral particles is impaired, although they are produced in high amounts. These subviral particles, which display an increased density and a predominantly filamentous morphology, accumulate at the endoplasmic reticulum. The PreS1PreS2 domain of genotype G, which forms aggregates, causes the block of HBsAg-secretion at the ER and leads to decreased transcriptional activator function of LHBs. Intracellular accumulation of HBsAg and impaired induction of the cytoprotective transcription factor Nrf2 lead to an elevated level of ROIs. This results in activation of JNK and as a consequence in Ser-phosphorylation of IRS-1, which is known to impair insulin signaling, a key factor for liver regeneration.

CONCLUSIONS

Although competent for release of viral particles, secretion of subviral particles is impaired in HBV/G expressing cells leading to ER-stress. In parallel, HBV-induced Nrf2 activation diminishes, which causes a decrease of the capacity to inactivate ROIs. This might be related to genotype-specific pathogenesis.

Risk Minimization Measures for Blood Screening HIV-1 Nucleic Acid Amplification Technique Assays in Germany

BACKGROUND

Several publications describe HIV-1 RNA false-negative results or viral load underquantitation associated with Communauté Européenne(CE)-marked qualitative or quantitative nucleic acid amplification technique (NAT) assays. 6 cases occurred during blood screening in Germany, with 2 of them causing HIV-1 transmissions to recipients of blood components. The implicated NAT assays were mono-target assays amplifying in different viral genome regions (gag or long terminal repeat).

METHODS

Specimens characterized by HIV-1 NAT underquantitation or false-negative NAT results were comparatively investigated in CE-marked HIV-1 NAT systems of different design to identify potential reasons. The target regions of the viral nucleic acids were sequenced and these sequences compared to primers and probes of the assays. Potential risk minimization measures were considered for quantitative and blood-screening HIV-1 NAT systems.

RESULTS

Nucleotide sequencing of the viral target region in cases of HIV-1 RNA underquantitation or false-negative test results revealed new HIV-1 variants that were mismatched with primers and probes used in some mono-target assays. So far, dualtarget NAT assays have not been associated with mismatch-based false-negative test results. From 2015, the Paul Ehrlich Institute will request HIV-1 NAT assays of dual-target design or an analogous solution for further reducing the risk in blood screening.

CONCLUSION

HIV differs from other blood-borne viruses with regard to its fast evolution of new viral variants. The evolution of new sequences is hardly predictable; therefore, NAT assays with only 1 target region appear to be more vulnerable to sequence variations than dual-target assays. The associated risk may be higher for HIV-1 NAT assays used for blood screening compared to quantitative assays used for monitoring HIV-1-infected patients. In HIV-1 screening NAT assays of dual-target design may adequately address the risk imposed by new HIV-1 variants.

Performance of hepatitis B surface antigen tests with the first WHO international hepatitis B virus genotype reference panel

BACKGROUND

Standardization of hepatitis B surface antigen (HBsAg) tests is indispensable for consistent quality and comparability. Ideally, the assays should detect all known hepatitis B virus (HBV) genotypes equally well.

OBJECTIVE

Development of an HBV genotype reference panel for HBsAg assays representing the most prevalent HBV subgenotypes to address commutability and traceability of the heat-inactivated 2nd WHO International Standard (IS) for HBsAg in relation to native HBsAg and to HBV genotypes.

STUDY DESIGN

An HBV panel of 15 non-inactivated lyophilized specimens representing the subgenotypes A1, A2, B1, B2, C2, D1-D3, E, F2, and H was evaluated in parallel to the IS by 15 laboratories using 19 different HBsAg tests and tree unitages. The virus content of the samples was reduced by ultracentrifugation and dilution to <2×10(4) IU HBV DNA/mL.

RESULTS

Twenty-two qualitative and 6 quantitative data sets were evaluated. Overall, the results demonstrated consistent detection of HBV genotypes by the majority of tests with a mean potency variability relative to the IS of 36%. Some assays showed significant genotype-dependent differences in analytical sensitivity. Some tests were more sensitive with the IS, others less. On average, one IU HBsAg corresponded to 0.88±0.20 ng HBsAg protein.

CONCLUSIONS

The panel was accepted by the WHO as the "1st International Reference Panel for HBV genotypes for HBsAg-based assays". The panel is a helpful complementation to the IS to validate HBV genotype specific analytical test sensitivities.

Infectivity of blood products from donors with occult hepatitis B virus infection

BACKGROUND

Occult hepatitis B virus (HBV) infection (OBI) is identified in 1:1000 to 1:50,000 European blood donations. This study intended to determine the infectivity of blood products from OBI donors.

STUDY DESIGN AND METHODS

Recipients of previous donations from OBI donors were investigated through lookback (systematic retrieval of recipients) or traceback (triggered by clinical cases). Serologic and genomic studies were undertaken on consenting donors and recipients. Multiple variables potentially affecting infectivity were examined.

RESULTS

A total of 45 of 105 (42.9%) donor-recipients pairs carried antibodies to HBV core (anti-HBc) as evidence of previous HBV infection. Subtracting 15% of anti-HBc population background, the adjusted transmission rate was 28%. Anti-HBc prevalence increased to 28 of 44 (63.8%) in unvaccinated recipients receiving anti-HBs-negative OBI blood products. In contrast, four of 26 (15.4%) recipients of anti-HBs-positive products were anti-HBc positive. Transmission with anti-HBs-negative products depended on volume of plasma transfused (85%-100% with 200 mL of fresh frozen plasma [FFP], 51% with 50 mL in platelet concentrates [PCs], and 24% with 20 mL in red blood cells [RBCs], p < 0.0001 FFP vs. RBCs). The 50% minimum infectious dose of OBI HBV DNA was estimated at 1049 (117-3441) copies. Donor and recipient strains sequence homology of at least 99% confirmed transfusion-transmitted infection in 10 cases and excluded it in one case.

CONCLUSION

Blood products from donors with OBI carry a high risk of HBV transmission by transfusion. This risk is dependent on presence of anti-HBs and viral dose. This may justify safety measures such as anti-HBc and HBV nucleic acid test screening depending on epidemiology.

First WHO International Reference Panel containing hepatitis B virus genotypes A-G for assays of the viral DNA

BACKGROUND

WHO International Standards (IS) are provided for the calibration and validation of diagnostic and screening assays, e.g. for hepatitis B virus (HBV). HBV forms numerous subgenotypes and the current IS for HBV DNA reflects subgenotype A2.

OBJECTIVE

A reference panel with the most prevalent subgenotypes should facilitate evaluation of genotype-specific detection efficiencies.

STUDY DESIGN

215 HBV positive plasma samples collected worldwide were characterized for HBV markers and sequenced. Fifteen subgenotype A1, A2, B2, B4, C2, D1, D3, E, F2 and G samples were selected for the panel. The lyophilized samples were tested in parallel with the IS in an international collaborative study with 16 laboratories using 13 different nucleic acid amplification techniques (NATs).

RESULTS

Eight of 13 NAT had a HBV DNA detection efficiency which was independent of the genotype and consistent with the IS, while with five assays, certain deviations were noted, particularly with genotype F which was under quantitated or even missed by three assays. The panel was accepted by the WHO as the "1st WHO International Reference Panel for HBV Genotypes for HBV NAT-Based Assays".

CONCLUSIONS

The evaluation of HBV DNA assays should include many different genotypes. The WHO Reference Panel is universally available for manufacturers of HBV DNA assays, diagnostic laboratories and control authorities to facilitate standardized validation of HBV genotype specific detection efficiency of both diagnostic (quantitative and qualitative) and screening NAT assays.

Blood screening nucleic acid amplification tests for human immunodeficiency virus Type 1 may require two different amplification targets

BACKGROUND

Five cases of human immunodeficiency virus Type 1 (HIV-1) RNA-positive blood donations are described that escaped detection by three different CE-marked nucleic acid amplification technique (NAT) screening assays. These events were associated with two HIV-1 transmissions to recipients of blood components. The implicated NAT assays are monotarget assays and amplify in different viral genome regions (group-specific antigen or long terminal repeat). Investigations into the cause of the false-negative test results were initiated.

STUDY DESIGN AND METHODS

Plasma specimens of the five NAT false-negative cases were comparatively investigated in 12 CE-marked HIV-1 NAT systems of differing design. The relative amplification efficiency for the HIV-1 variant was determined for each assay. Sequencing of the variants in the region targeted by each false-negative NAT assay allowed comparison with the respective primers and probes.

RESULTS

Some of the NAT assays designed in a similar way to false-negative monotarget NATs also revealed deficiencies in detecting the viral variants. In each case sequencing of the assay target region in the variants demonstrated mismatches with primers and probes used by the assays. Some dual-target assays showed decreased amplification efficiency, but not false-negative results.

CONCLUSION

HIV is characterized by its rapid evolution of new viral variants. The evolution of new sequences is unpredictable; NAT screening assays with a single target region appear to be more vulnerable to sequence variations than dual-target assays. Based on this experience with false-negative tests results by monotarget NAT assays, the Paul-Ehrlich-Institut is considering requesting dual-target NAT assays for HIV-1 blood donation screening in Germany.

Collaborative study to establish a replacement World Health Organization International Standard for parvovirus B19 DNA nucleic acid amplification technology (NAT)-based assays

BACKGROUND AND OBJECTIVES

The aim of the study was to replace the 1(st) World Health Organization International Standard for parvovirus B19 DNA for nucleic acid amplification technique (NAT)-based assays (code 99/800). Two lyophilized preparations (coded 99/800 and 99/802) had been evaluated in the original collaborative study. The present study re-evaluates these two preparations in terms of potency, stability and encapsidation of virus DNA.

MATERIALS AND METHODS

The 1(st) International Standard (99/800) and 99/802 were re-coded as Samples 1 and 2, respectively. The samples were distributed to six laboratories and assayed on four separate occasions. Accelerated thermal degradation samples of the two preparations were examined after storage at 20 degrees C for 7 years. Nuclease treatment was used to investigate the encapsidation of virus DNA.

RESULTS

Data were returned from a total of six different quantitative NAT-based assays. The results of the present study confirm those of the original, with no significant differences found in estimated international units (IU)/ml for the 1(st) International Standard (Sample 1 in this study) and the proposed replacement preparation, Sample 2 (99/802). Accelerated thermal degradation studies demonstrate that both samples are very stable, with no loss of potency after storage at 20 degrees C for 7 years. Both lyophilized preparations contained the majority of B19V DNA encapsidated in virions.

CONCLUSIONS

On the basis of the data presented in this collaborative study, Sample 2 (code number 99/802) was established as the 2(nd) International Standard for parvovirus B19 DNA for NAT-based assays with a potency of 10(6) IU/ml (500 000 IU/vial).

Experience of mandatory nucleic acid test (NAT) screening across all blood organizations in Germany: NAT yield versus breakthrough transmissions

BACKGROUND

Mandatory nucleic acid test (NAT) blood screening was introduced in Germany in 1999 for hepatitis C virus (HCV) RNA and in 2004 for human immunodeficiency virus Type 1 (HIV-1) RNA. Minimal sensitivity limits of 5000 IU HCV RNA/mL and 10,000 IU HIV-1 RNA/mL were defined for the individual donation facilitating testing of minipools (MPs). The NAT yield obtained from all blood organizations is summarized. Transfusion-associated virus transmissions despite NAT screening ("breakthrough transmissions") are analyzed.

STUDY DESIGN AND METHODS

In Germany, a variety of NAT assays is applied for NAT screening pool sizes of up to 96 donations. Subsets of NAT yield cases were characterized with regard to viral loads by quantitative NAT and with regard to viral genotypes. Confirmed breakthrough transmissions were analyzed using different molecular and serologic assays.

RESULTS

Ninety-two HCV NAT yield cases among 40.8 million and 11 HIV-1 NAT yield cases among 17.1 million donations were identified. During this period, one transmission case was confirmed for HCV and one for HIV-1. The two incidents escaped NAT detection because of low-level viremia and/or suboptimal amplification efficiency. Evidence was obtained for a case of HIV-1 nontransmission by a low-level HIV-1 contaminated red blood cell unit.

CONCLUSION

NAT screening of MPs identified the vast majority of window-phase donations. A significant number of transmission cases was interdicted; breakthrough transmissions may still occur as rare events, even with individual-donation NAT in place. Sensitivity limits might be adapted to the current "state of the art" taking account of viral dynamics during early infection, incidence rates, and costs.

First transmission of human immunodeficiency virus Type 1 by a cellular blood product after mandatory nucleic acid screening in Germany

BACKGROUND

In February 2007, a 63-year-old man underwent surgery. Retrospective testing with nucleic acid testing (NAT) showed that the patient was human immunodeficiency virus Type 1 (HIV-1) positive 10 days after transfusion. The transfusion-transmitted infection had been identified by a donor-related lookback started in April 2007 after anti-HIV seroconversion.

METHODS

Sequence analysis was performed in the gag-pol region as well as in the V3 loop env region. Archived plasma from the transmitting donation was investigated for the individual-donation NAT with the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 test (Roche CAP/CTM HIV-1 test) and for HIV antigen/antibody combination testing (Abbott Architect). Additional testing was done on the donor's follow-up sample and on the recipient's sample.

RESULTS

The Roche CAP/CTM HIV-1 test failed to detect viral RNA by minipool NAT in the index donation (April 2007) as well as in the donation that caused the infection (January 2007). Phylogenetic analysis showed a very high genetic similarity among viral sequences from both donor and recipient, proving the HIV-1 transmission by sequence data.

CONCLUSION

This case represents the first documented HIV-1 transmission by transfusion of red blood cells after mandatory introduction of HIV-1 NAT for blood screening in Germany. Low viral load and mismatches in the primer/probe region might explain the detection failure of the NAT screening assay. A certain risk remains that new virus variants contain mutations at positions critical for amplification or detection of viral genomes. An option to reduce the risk of a detection failure by NAT is the simultaneous use of several conserved regions as amplification targets.

Consistency of quantitation of HCV genotype 4 from egypt across three HCV-RNA amplification assays

Different quantitative assays for HCV-RNA are available that report test results in International Units (IU)/ml based on the WHO International Standard. Thus, assays have been calibrated with standard material containing HCV genotype 1, so the consistency of quantitation might differ between assays for other HCV genotypes. Three commercial HCV nucleic acid amplification techniques (HCV-NAT) were compared for quantitation consistency of genotype 4 and 1 specimens from an Egyptian blood donor panel (n = 92). Consistency of quantitation between HCV-NATs was higher for genotype 1 than for genotype 4. Most quantitative results reported by the assays were in the same range, but some genotype 4 samples were missed by two of the assays. The Abbott assay showed higher concentrations for genotype 4 than the two Roche assays. Follow-up investigations of individuals should use the same assay unless another assay has been validated properly. Standardization of HCV-NAT assays remains an issue.

Effect of viral nucleic acid testing on contamination frequency of manufacturing plasma pools

BACKGROUND

In Europe, all plasma pools used for manufacturing of plasma derivatives must be tested negative for hepatitis C virus (HCV) RNA by nucleic acid amplification techniques (NAT) with a defined minimal sensitivity. For a subset of pools, quantitative B19V DNA NAT is also mandatory. NAT for further viral targets was introduced by most of the manufacturers on a voluntary basis. The contamination frequency of plasma pools with HCV RNA, human immunodeficiency virus (HIV)-1 RNA, and hepatitis B virus (HBV) DNA was investigated with representative pools before and after introduction of NAT.

STUDY DESIGN AND METHODS

A total of 873 pools from 1996 and 331 pools from 2006 were analyzed for the detection of HCV RNA, HIV RNA, and HBV DNA with an automated multiplex NAT system. The pools were obtained from different manufacturers and the source material was of European and US origin.

RESULTS

HCV RNA, HIV-1 RNA, and HBV DNA were detectable in plasma pools from 1996 with the following frequencies: 17.8 percent (HCV RNA), 0.8 percent (HIV-1 RNA), and 0.5 percent (HBV DNA). Viral genome concentrations were up to 3 x 10(4) IU HCV RNA per mL and 7 x 10(3) IU HIV RNA per mL, whereas HBV DNA was below the quantitation limit of the quantitative NAT assay. Among the pools from 2006, one pool (0.3%) was found HCV RNA-positive at low titer (<10 IU/mL), whereas no HIV RNA or HBV DNA was detectable in any pool.

CONCLUSION

The results imply that the introduction of NAT systems for the detection of viral genomes has largely reduced the contamination frequency and viral loads of manufacturing plasma pools and thereby improved the safety margin for human medicinal products manufactured from human plasma. Even with NAT, however, low-titer contamination may occur, which will be coped with by virus inactivation steps included into the manufacturing of plasma derivatives.

An international collaborative study to establish the 2nd World Health Organization International Standard for hepatitis B virus DNA nucleic acid amplification technology-based assays

BACKGROUND AND OBJECTIVES

The aim of this study was to replace the 1st World Health Organization International Standard for hepatitis B virus DNA for nucleic acid amplification technique (NAT)-based assays (code 97/746) with a new International Standard. Two lyophilized preparations freeze dried from the same bulk were evaluated in the original collaborative study (coded 97/746 and 97/750, and termed AA and BB, respectively, in the original study). This present study re-evaluates these two preparations in terms of potency and real-time stability.

MATERIALS AND METHODS

The 1(st) International Standard (97/746) and the second lyophilized preparation (97/750) were coded Samples 1 and 2, respectively, in the present study. The samples were distributed to six laboratories and assayed on four separate occasions. Accelerated thermal degradation samples of the two preparations were examined after long-term storage at 4 degrees C and 20 degrees C for more than 51 months.

RESULTS

Data were returned from a total of nine different NAT-based assays, five in qualitative format and four in quantitative format. The results of this study confirm the results of the original collaborative study, with no significant differences being found in estimated international units (IU)/ml or polymerase chain reaction-detectable units/ml for the 1(st) International Standard (Sample 1 in this study) and the proposed replacement preparation, Sample 2 (97/750). Real-time and accelerated degradation studies indicate that both samples are very stable. Storage of both preparations at 20 degrees C for more than 51 months resulted in no detectable degradation.

CONCLUSIONS

On the basis of the data presented in this collaborative study, Sample 2 (code 97/750) was established as the 2nd International Standard for hepatitis B virus DNA for NAT-based assays with a potency of 10(6) IU/ml (500,000 IU/vial).

First case of hepatitis C virus transmission by a red blood cell concentrate after introduction of nucleic acid amplification technique screening in Germany: a comparative study with various assays

BACKGROUND AND OBJECTIVES

Pooled nucleic acid amplification techniques (NAT) and donor screening for anti-hepatitis C virus (HCV) have reduced the diagnostic window period of HCV infection in the blood donor population from about 12 to 1 or 2 weeks. During that time, HCV RNA is hardly detectable by pooled or individual donation NAT. Here we describe a case of transfusion-acquired HCV infection from an extremely low-titre donation. After a repeat donor tested positive for HCV, a look-back procedure was initiated. A recipient of a red cell concentrate from the previous donation was identified and found to be infected with HCV as well. We compared several commercial NAT systems for their ability to detect the viraemic plasma.

MATERIALS AND METHODS

Molecular analyses of HCV in donor and recipient samples were performed. The HCV-transmitting plasma was tested using different commercially available qualitative and quantitative NAT assays.

RESULTS

HCV transmission was verified by molecular analyses and was assigned to genotype 2b. NAT with various commercial HCV assays detected the infection erratically in individual donations. However, the detection rate was not directly related to the claimed sensitivity of some HCV NATs.

CONCLUSIONS

HCV transmission can be caused by donations that escape NAT detection even when tested in an individual donation. Comparison of different assays led to results that did not necessarily reflect the expected sensitivities. The need for standard materials representing further HCV genotypes is discussed.

Anti-HBc screening of blood donors: a comparison of nine anti-HBc tests

BACKGROUND AND OBJECTIVES

Since voluntary introduction of hepatitis B virus (HBV) minipool nucleic acid amplification technology (NAT) at the German Red Cross, the expected residual risk of a transfusion-associated HBV infection has been estimated to be 1 : 500,000 - about 10 times higher than for human immunodeficiency virus (HIV) or hepatitis C virus (HCV) infection. Donors demonstrating chronic positivity for antibody to hepatitis B core antigen (anti-HBc), negativity for hepatitis B surface antigen (HBsAg) and polymerase chain reaction (PCR)-negative with a low virus load are a major cause of this increased risk.

MATERIALS AND METHODS

Ten-thousand blood donors from our blood-donation centre were screened for anti-HBc using the current PRISM HBc and the new PRISM HBcore assay to evaluate the diagnostic sensitivity and specificity of these tests. PRISM HBc- or PRISM HBcore-reactive samples were further analysed using seven additional tests for anti-HBc, two tests for antibody to hepatitis B surface antigen (anti-HBs), one test for antibody to hepatitis B envelope antigen (anti-HBe) and three HBV NAT assays.

RESULTS

From a total of 10,000 donors, nine and 14 samples were reactive only in the PRISM HBc and the PRISM HBcore, respectively, whereas 165 samples were reactive in both anti-HBc assays. Further analysis of these 188 anti-HBc-reactive specimens in a total of nine different anti-HBc assays revealed concordant results for 162 (86.2%) specimens. Sample cut-off values for anti-HBc were significantly (P < 0.01) lower for anti-HBc-only reactive samples compared with specimens that were also reactive for anti-HBs or anti-HBe.

CONCLUSIONS

Both PRISM anti-HBc assays revealed that approximately 1.8% of non-prescreened blood donors from Germany were reactive for anti-HBc. Although sensitivity was comparable between both assays, specificity was increased significantly with the PRISM HBcore. High anti-HBc sample cut-off values were indicative for reactivity in other HBV parameters and for concordant results in the nine different anti-HBc assays. Look-back investigations are necessary to estimate the infection risk both of anti-HBc-only positive and of anti-HBc/anti-HBs-positive blood transfusions.

Neopterin levels during the early phase of human immunodeficiency virus, hepatitis C virus, or hepatitis B virus infection

BACKGROUND

A study was conducted to assess the diagnostic sensitivity of neopterin screening of blood donors with regard to the detection of window-phase specimens of human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) infection.

STUDY DESIGN AND METHODS

In total, 1002 diagnostic window-phase specimens from 98 seroconversion panels (29 HIV-1, 52 HCV, and 17 HBV) were analyzed with viral antigen detection, viral nucleic acid amplification testing (NAT), and neopterin quantitation assays. The study was completed by the analysis of 92 anti-hepatitis B core antigen (HBc)-reactive and 103 alanine aminotransferase (ALT)-elevated blood donor specimens.

RESULTS

A significant association between elevated neopterin concentrations and the very early phase of HIV-1 infection was found. No significant correlation could be observed between neopterin levels and the early phase of HCV or HBV infection. Neopterin concentration was not increased in specimens from blood donors with anti-HBc reactivity or ALT elevation.

CONCLUSIONS

Neopterin screening of blood donors may identify window-phase cases of HIV, but not of HCV or HBV infection. The diagnostic sensitivity of neopterin screening during the HIV window phase is similar to that of the p24 antigen test. With the introduction of viral NATs in blood screening, there is no additional benefit of neopterin screening with regard to the three blood-borne viruses HIV, HCV, and HBV. Acute phases of other infectious agents, however, have been reported to be detected by neopterin enzyme-linked immunosorbent assays.

Hepatitis B virus genotype G monoinfection and its transmission by blood components

An acute hepatitis B virus (HBV) infection was diagnosed in a regular apheresis (plasma/platelet) donor by the hepatitis B surface antigen (HBsAg) assay and minipool nucleic acid amplification technology (NAT). The acute infection was confirmed by detection of anti-HBc (IgM) and anti-HBs 2 weeks later. The donor showed no clinical symptoms and had normal alanine aminotransferase levels. He had a history of weekly apheresis plasma or platelet donations. Archived material from the donor and the respective recipients was investigated by sensitive HBV NATs as part of a look-back procedure. HBV DNA was detectable in previous donations as well as in two recipients transfused with platelet concentrates. The rare HBV genotype G was identified in all HBV-DNA-positive samples. Strong evidence of genotype G monoinfection was obtained by clonal sequencing, HBV genotype line probe assay, genotype-specific NATs, and restriction pattern analysis. In contrast to previously described genotype G infections, which all appeared as coinfections with genotype A, neither the hepatitis B e antigen (HBeAg) nor anti-HBe was detectable in any of the samples. This shows that HBeAg is dispensable for viral replication. The delay in detecting HBsAg in both the donor and recipient samples may be explained by either decreased genotype G-specific synthesis of incomplete viral forms in early HBV infection or the lower sensitivity to genotype G of the current HBsAg assays. In conclusion, this reported case of an HBV infection was caused exclusively by genotype G.

Molecular epidemiology of West Nile Virus in humans

After the introduction of West Nile Virus into the United States of America in 1999 followed by annual WNV epidemics during the mosquito seasons and spreading of the virus from the East (New York; 1999) to the West of the U.S. (California; 2003/2004) there appeared the question of whether a similar scenario could happen in Europe, too. To be able to answer this question the German Ministry of Health decided to investigate the prevalence and incidence of WNV infections in German blood donors. First a test algorithm was established taking into account the high level of cross-reactivity between different flavivirus infections in serological test systems. AntiWNV-suspicious specimens were further investigated for their neutralisation capacity and by an antiWNV confirmation assay developed in-house. As a preliminary result of our studies a very low prevalence of WNV infections in healthy German blood donors was measured. Development of highly specific test systems is necessary for accurate and reliable differential diagnosis of flavivirus infections.

Multicenter performance evaluation of a transcription-mediated amplification assay for screening of human immunodeficiency virus-1 RNA, hepatitis C virus RNA, and hepatitis B virus DNA in blood donations

BACKGROUND

The performance of the recently launched Procleix Ultrio (Chiron/Gen-Probe) human immunodeficiency virus-1 (HIV-1), hepatitis C virus (HCV), and hepatitis B virus (HBV) blood screening assay was evaluated in a European multicenter study.

STUDY DESIGN AND METHODS

Serial dilutions of reference materials were tested to determine the detection limits. Robustness and specificity were assessed by testing alternating high-load HCV RNA-positive and -negative samples, and 2912 test pools of eight donations. The added value of minipool and single-donation HBV nucleic acid testing protocols was compared to the currently used Prism (Abbott GmbH & Co. KG) hepatitis B surface antigen (HBsAg) and Auszyme (Abbott GmbH & Co. KG) dynamic HBsAg tests in 15 HBV seroconversion panels.

RESULTS

The 95 percent detection limits (and 95% confidence interval [CI]) on the WHO International Standards was 26 (16-58) IU per mL for HIV-1 RNA, 4.6 (3.7-6.5) IU per mL for HCV RNA, and 11 (7.3-22) IU per mL for HBV DNA. No cross-contamination was observed. Testing 2912 pools of eight donations revealed 16 initial reactive samples; 11 were confirmed. The specificity after initial testing and percentage of invalid results were 99.83 and 0.48 percent, respectively. The HBV window-period (WP) reductions relative to HBsAg seroconversion in Prism and Auszyme dynamic HBsAg were, respectively, 6 days (95% CI, 3-8) and 9 days (95% CI, 7-12) in 1:8 minipool (MP) testing.

CONCLUSION

The performance characteristics of Procleix Ultrio assay and the Procleix HIV-1 and HCV assay are comparable. The sensitivity for HIV-1 and HCV met the directives of the Paul-Ehrlich Institute and the FDA. The assay can reduce the WP for HBV by 6 days to 2 weeks when used in small MP (<1:8) or single-donation screening protocols.

A natural asymptomatic herpes B virus infection in a colony of laboratory brown capuchin monkeys (Cebus apella)

Herpes B virus (BV) infection of macaques persists in the natural host, but is mainly asymptomatic. However, BV can cause fatal disease in humans and in several non-macaque species such as capuchin monkeys (Cebus apella). The BV infection described here in a colony of capuchin monkeys was persistent but asymptomatic. Initially the infection was detected serologically in five out of seven animals. However, using polymerase chain reaction (PCR) developed specifically for BV, we found the virus in all seven clinically healthy animals. It is probable that the infection was transferred from BV-infected macaques housed in different cages but in the same room for several years. We have no evidence to indicate that similar asymptomatic infections may occur in other New World species but the possibility should not be discounted. We recommend that the housing of capuchin monkeys in close proximity to macaques should be avoided and that greater caution should be used when handling capuchin monkeys and possibly other New World species that have been in contact with macaques. All may act as a source of BV infection in humans, hence routine, repeated testing of all primates is essential.