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BACKGROUND: Disease morbidity of tick-borne encephalitis (TBE) has been increasing over the last decades. Since the 1990s, however, no extensive seroprevalence studies on TBE in humans have been performed in Switzerland. Here we assessed the prevalence of anti-TBE virus (TBEV) antibodies among different groups of the Swiss blood donor population. MATERIALS AND METHODS: The study was carried out from July 2014 to January 2015. Blood donors participating in the study (n=9,328) were asked to fill in a questionnaire relating to vaccination against or infection with different flaviviruses, and blood samples were collected. All samples were screened for the presence of anti-TBEV IgG antibodies using ELISA testing. Seropositivity rates in different groups of blood donors were compared using Chi square tests with Bonferroni correction. RESULTS: In 2014 and 2015, 24.6% of healthy Swiss blood donors indicated vaccination against TBE. Among vaccinated blood donors, antibody prevalence was significantly higher in younger (

Background: Malaria is a mosquito-borne infectious disease caused by protozoan parasites of the genus Plasmodium. As migration of populations from endemic areas to Europe and overseas recreational travel to endemic regions increase, there is also a growing risk of transfusion-transmitted tropical diseases by blood components. Material and Methods: In the present study two routine Plasmodium spp. ELISA (CAPTIA™ Malaria EIA, Trinity Biotech, and Malaria EIA, BioRad) were compared with a new commercial ELISA (ELISA IgG, EUROIMMUN). From December 1, 2015 until November 30, 2016, 1,096 plasma samples from blood donors with a potential risk of malaria infection were collected at two blood transfusion centres in Germany and Switzerland. Results: The samples were tested comparatively with the ELISA from EUROIMMUN and the routine test used at the respective centre. Thirty-four of 595 (5.7%) tested blood samples from centre 1 and 49 of 501 (9.8%) tested blood samples from centre 2 showed reactivity on either or both ELISAs. All 83 reactive samples were sent for confirmation to the Diagnostic Centre of the Swiss Tropical and Public Health Institute (Swiss TPH) in Basel, Switzerland. Sixteen samples, which previously were reactive in the routine Plasmodium spp. EIA assays, were proven positive after confirmation testing (i.e., 4 positive and 12 inconclusive results), indicating an anti-Plasmodium antibody prevalence in blood donations of 1.5%. From these 16 reactive samples, 13 were also detected by the index test, resulting in an assay sensitivity of 81.2%. A specificity of 98.6% was calculated (1,065/1,080 confirmed negative samples). The overall agreement with the reference centre was 95.8% in centre 1 and 94% in centre 2. Conclusion: The comparison of the new EUROIMMUN ELISA and the established CAPTIA™ Malaria EIA (Trinity Biotech) and Malaria EIA (BioRad) used for routine blood donor screening in two laboratory blood donation centres revealed that all tested ELISAs show comparable sensitivities and are equally suitable for anti-Plasmodium antibody screening in blood banks.

OBJECTIVETo determine the seroprevalence of SARS-CoV-2 antibodies in employees of the Cantonal Police Bern, Switzerland; to investigate individual and work-related factors associated with seropositivity; and to assess the neutralizing capacity of the antibodies of seropositive study participants.DESIGNCross-sectional analysis of a cohort study.SETTINGWearing face masks was made mandatory for employees of the police during working hours at the rise of the second wave of the pandemic in mid-October 2020. Protests and police fieldwork provided a high exposure environment for SARS-CoV-2 infections. The investigation was performed prior to initiation of a vaccine programme. Study participants were invited for serological testing of SARS-CoV-2 and to complete questionnaires on sociodemographic, work and health-related questions.PARTICIPANTS978 police personnel working in four different geographic districts, representing 35% of the entire staff, participated from February to March 2021.MAIN OUTCOME MEASURESSeroprevalence of anti-SARS-CoV-2 antibodies in February to March 2021, geographic and work-related risk factors for seropositivity, and serum neutralization titres towards the wild-type SARS-CoV-2 spike protein (expressing D614G) and the alpha and beta variants.RESULTSSeroprevalence was 12.9% (126 of 978 employees). It varied by geographic region within the canton; ranged from 9% to 13% in three regions, including the city; and was 22% in Bernese Seeland/Jura. Working in the latter region was associated with higher odds for seropositivity (odds ratio 2.38, 95% confidence interval 1.28 to 4.44, P=0.006). Job roles with mainly office activity were associated with a lower risk of seropositivity (0.33, 0.14 to 0.77, P=0.010). Most seropositive employees (67.5%) reported having had coronavirus disease 2019 (COVID-19) 3 months or longer prior to serological testing, and the proportion of agreement between positive nasopharyngeal test results and seroconversion was 95% to 97%. Among reported symptoms, new loss of smell or taste was the best discriminator for seropositivity (odds ratio 52.4, 30.9 to 89.0, PCONCLUSIONSSeroprevalence in the pre-vaccinated police cohort was similar to that reported in the general population living in the same region. The high compliance with mask wearing and the low proportion of seroconversion after contact with a presumed or proven COVID-19 case during working hours imply that personal protective equipment is effective and that household contacts are the leading transmission venues. The level of serum antibody titres, in particular that of anti-spike antibodies, correlated well with neutralization capacity. Low antibody titres were not effective against the alpha and beta variants.SUMMARY BOXESWHAT IS ALREADY KNOWN ON THIS TOPICThe seroprevalence of anti-SARS-CoV-2 antibodies in the general population shows variations, depending on the geographic location of investigated study participants.Social distancing by avoiding crowds and maintaining a distance of 6 feet from others when in public are recommended. These recommendations are not realistic for security personnel and employees of a police department.Preventive strategies for individuals in a health care setting are warranted and effective to reduce potential exposures. The effect of preventive strategies on individuals working for the police force has not been investigated.WHAT THIS STUDY ADDSThe study suggests that the overall seroprevalence of anti-SARS-CoV-2 antibodies among police officers is not higher than that in the general population, despite presumed higher exposure (e.g., public protests).Compliance with use of personal protective equipment among police officers was very high. The study results suggested that household contacts, rather than exposure during working hours, is the main source for viral transmission.Anti-SARS-CoV-2 antibodies derived from natural infection demonstrated good neutralization capacity towards strains that epidemiologically likely caused the infection, but moderate to poor neutralization capacity towards the alpha and beta variant.

Introduction: A highly sensitive and specific nucleic acid test (NAT) for the blood-borne viruses human immunodeficiency virus (HIV), hepatitis C (HCV), and hepatitis B (HBV) is essential for the safety of blood components. Since more than 2 decades, NAT screening of blood donations has become standard in developed countries that have implemented the individual-donation (ID-NAT) and mini-pool NAT (MP-NAT) approaches. With this powerful technique, confirmation of initial reactive (IR) NAT samples becomes a challenge. Different algorithms are currently in use to eliminate false reactive results. To show that the algorithm implemented in 2007, that uses repeat testing of IR samples in duplicate runs, is a safe strategy, especially in low endemic countries, data from a 10-year experience of ID-NAT were extensively analyzed when follow-up data were available. Methods: From July 2007 to December 2014, the Procleix Ultrio assay on a Procleix Tigris system, and from January 2015 to December 2017, the cobas MPX on a cobas 8800 platform, were used for ID-NAT screening. All IR samples were subjected to repeat testing in duplicate independent runs. Only when both tests remained negative were the products released. Donor data from the last 10 years were investigated retrospectively, looking for the reoccurrence of a reactive result in a follow-up sample. Only those donors with at least an x + 1 donation result were included for the confirmation of a false reactive result. Results: From the 1,830,657 donations tested, 2,450 samples were IR (0.13%); only 228 were repeat reactive ([RR], 18 HIV, 61 HCV, and 149 HBV samples), and 2,222 were non-RR (0.12%). Follow-up data were available from 1,267 donors (57%) for further analysis. All except one of these donors were ID-NAT-negative in all follow-up samples. The one exception was from a donor who acquired a fresh HBV infection 10 years after the IR donation (in the x + 28 donation) and subsequently seroconverted. Subsequent serological tests from all succeeding donations (x + 1, x + 2, etc.) were negative in all the other cases, proving that no seroconversion took place after the IR ID-NAT result. Conclusions: The algorithm to deal with IR ID-NAT donations using duplicate repeat testing is very safe and cost-effective in low-prevalence countries. There is no unnecessary destruction of blood products, no counseling of false reactive donors, and also no need to add further complexity to the screening algorithm.

Background: Population migrations and overseas recreational travel to regions at risk for tropical diseases are increasing. A major challenge in non-endemic countries is to decrease the number of blood donor deferrals due those tropical disease pathogens, without compromising the high level of blood safety. The protozoans Trypanosoma cruzi and Plasmodium spp., the causative organisms of Chagas disease (CD) and malaria are becoming a major focus in the blood transfusion community. Methods: National guidelines of the Blood Transfusion Service of the Swiss Red Cross propose an algorithm for dealing with these pathogens, including a mandatory selective serological testing of donors at risk. Results: 6,978 donors at risk for CD were tested. Three of them were confirmed anti-T. cruzi-positive, and in one case a transfusion-transmitted infection was highly possible. The specificity of the assay was 99.94%. For malaria 12,887 donors were at risk and 178 were confirmed positive. The specificity of the assays was 92.8%. Conclusion: CD and malaria in non-endemic countries may represent a certain risk for blood transfusion. Switzerland chose a selective testing approach. The specificity of the assays is a crucial topic for this approach because it ensures a minimal loss of false-reactive donors and helps towards an easier counselling of implicated donors.

Background and aim Hepatitis E virus (HEV) is a virus of emerging importance to transfusion medicine. Studies from several European countries, including Switzerland, have reported high seroprevalence of hepatitis E as a consequence of endemic infections. Published HEV seroprevalence estimates within developed countries vary considerably; primarily due to improved diagnostic assays. The purpose of this study was to investigate the seroprevalence of anti-HEV IgG in Swiss blood donations. Methods: We used the highly sensitive Wantai HEV IgG EIA and assessed regional distribution patterns. We analysed age- and sex-matched archive plasma dating back 20 years from canton Bern to investigate recent changes in HEV seroprevalence levels. Results: On average, 20.4% (95% confidence intervals: 19.1–21.8) of the 3,609 blood samples collected in 2014–16 were anti-HEV IgG positive; however, distinct differences between geographical regions were observed (range: 12.8–33.6%). Seroprevalence increased with age with 30.7% of males and 34.3% of women being positive donors over > 60 years old. Differences between sexes may be attributed to dissimilarities in the average age of this group. Within the specified region of the Bern canton, overall prevalence has declined over two decades from 30.3% in 1997/98 to 27.0% in 2006 and 22.3% in 2015/6. Conclusions: HEV seroprevalence in Switzerland is high, but has declined over the last decades. The result shows that primarily endemic HEV infections occur and that current blood products may pose a risk to vulnerable transfusion recipients. Nucleic acid screening of all blood products for HEV will begin in November 2018.

Background: High-frequency blood group antigens (HFA) are present in >90% of the human population, according to some reports even in >99% of individuals. Therefore, patients lacking HFA may become challenging for transfusion support because compatible blood is hardly found, and if the patient carries alloantibodies, the cross-match will be positive with virtual every red cell unit tested. Methods: In this study, we applied high-throughput blood group SNP genotyping on >37,000 Swiss blood donors, intending to identify homozygous carriers of low-frequency blood group antigens (LFA). Results: 326 such individuals were identified and made available to transfusion specialists for future support of patients in need of rare blood products. Conclusion: Thorough comparison of minor allele frequencies using population genetics revealed heterogeneity of allele distributions among Swiss blood donors which may be explained by the topographical and cultural peculiarities of Switzerland. Moreover, geographically localized donor subpopulations are described which contain above-average numbers of individuals carrying rare blood group genotypes.

IntroductionOut-of-hospital cardiac arrest is one of the leading causes of death in industrialised countries. Survival depends on prompt identification of cardiac arrest and on the quality and timing of cardiopulmonary resuscitation (CPR) and defibrillation. For laypeople, there has been a growing interest on hands-only CPR, meaning continuous chest compression without interruption to perform ventilations. It has been demonstrated that intentional interruptions in hands-only CPR can increase its quality. The aim of this randomised trial is to compare three CPR protocols performed with different intentional interruptions with hands-only CPR.Methods and analysisThis is a prospective randomised trial performed in eight training centres. Laypeople who passed a basic life support course will be randomised to one of the four CPR protocols in an 8 min simulated cardiac arrest scenario on a manikin: (1) 30 compressions and 2 s pause; (2) 50 compressions and 5 s pause; (3) 100 compressions and 10 s pause; (4) hands-only. The calculated sample size is 552 people. The primary outcome is the percentage of chest compression performed with correct depth evaluated by a computerised feedback system (Laerdal QCPR).Ethics and dissemination. Due to the nature of the study, we obtained a waiver from the Ethics Committee (IRCCS Policlinico San Matteo, Pavia, Italy). All participants will sign an informed consent form before randomisation. The results of this study will be published in peer-reviewed journal. The data collected will also be made available in a public data repository.Trial registration numberNCT02632500.

Background Nucleic acid test (NAT) hepatitis B virus (HBV) screening for all blood donations with a sensitivity limit of 25 IU/mL in the individual donation is mandatory in Switzerland since 2009. The aims of the two studies were to define the percentage of antibody to hepatitis B core antigen (anti-HBc) or anti-HBc and antibody to hepatitis B surface antigen (anti-HBs)-positive donors bearing HBV DNA and to gather HBV viral load data on HBV NAT yields during the routine screening since the introduction of the HBV NAT. Study Design and Methods Archive samples from anti-HBc–positive donors (Group I) were analyzed with a quantitative HBV DNA test and further with anti-HBc and anti-HBs assays. In addition, all the HBV NAT-only–yield samples (Group II) from the routine donor screening performed between July 2007 and May 2013 were included in the study. Results From the 667 samples investigated (131 donors), three donors (2.3%) had donated eight samples (1.2%) with detectable HBV DNA; however, all had very low viral loads (≤10 IU/mL). From the 1,160,426 donations screened with the routine HBV NAT assay, 16 HBV NAT yields were detected: two window period (WP) and 14 occult hepatitis B infection (OBI) cases. In eight of these positive donations (two WP and six OBI), the HBV viral loads were not more than 10 IU/mL, in three cases between 10 and 25 IU/mL, and in the remaining five donations between 37 and 166 IU/mL. Conclusion The highly sensitive HBV NAT assay with a threshold significantly below 10 IU/mL is a valuable alternative to anti-HBc and a less sensitive HBV NAT screening in blood donor screening.

BACKGROUND: The risk of transfusion-transmitted hepatitis B virus (HBV) in Switzerland by testing blood donors for hepatitis B surface antigen (HBsAg) alone has been historically estimated at 1:160,000 transfusions. The Swiss health authorities decided not to introduce mandatory antibody to hepatitis B core antigen (anti-HBc) testing but to evaluate the investigation of HBV nucleic acid testing (NAT). STUDY DESIGN AND METHODS: Between June 2007 and February 2009, a total of 306,000 donations were screened routinely for HBsAg and HBV DNA by triplex individual-donation (ID)-NAT (Ultrio assay on Tigris system, Gen-Probe/Novartis Diagnostics). ID-NAT repeatedly reactive donors were further characterized for HBV serologic markers and viral load by quantitative polymerase chain reaction. The relative sensitivity of screening for HBsAg, anti-HBc, and HBV DNA was assessed. The residual HBV transmission risk of NAT with or without anti-HBc and HBsAg was retrospectively estimated in a mathematical model. RESULTS: From the 306,000 blood donations, 31 were repeatedly Ultrio test reactive and confirmed HBV infected, of which 24 (77%) and 27 (87%) were HBsAg and anti-HBc positive, respectively. Seven HBV-NAT yields were identified (1:44,000), two pre-HBsAg window period (WP) donations (1:153,000) and five occult HBV infections (1:61,000). Introduction of ID-NAT reduced the risk of HBV WP transmission in repeat donors from 1:95,000 to 1:296,000. CONCLUSIONS: Triplex NAT screening reduced the HBV WP transmission risk approximately threefold. NAT alone was more efficacious than the combined use of HBsAg and anti-HBc. The data from this study led to the decision to introduce sensitive HBV-NAT screening in Switzerland. Our findings may be useful in designing more efficient and cost-effective HBV screening strategies in low-prevalence countries.

The performance of the rapid confirmatory HIV 1/2 assay Geenius was compared with the conventional HIV 1/2 line immunoblot (INNO-LIA HIV I/II Score). One hundred HIV 1/2 confirmed positive samples from donors and patients and 136 negative screening samples from blood donors were evaluated with both assays. A 20 member performance panel consisting of different HIV 1 and 2 subtypes was also analysed. Ninety-nine of the confirmed HIV positive samples were positive with both assays. One sample was positive with the INNO-LIA HIV I/II Score but indeterminate with the Geenius HIV 1/2. From 136 negative blood donor samples (negative with a combo HIV assay and a highly sensitive ID-NAT), 125 were concordant negative. Six and five samples were incorrectly indeterminate with the INNO-LIA HIV I/II Score and the Geenius HIV 1/2, respectively. One sample was weak positive with the INNO-LIA HIV I/II Score but negative with the Geenius HIV 1/2. The 20 member performance showed equivalent results with both assays. The rapid assay showed a comparable sensitivity and specificity for confirmation for positive and negative HIV donor and patient samples as well for a 20 member performance panel.

Objective : The increasing use of intravenous immunoglobulins (IVIg) to treat systemic inflammatory, mostly autoimmune, diseases raises the concern that their competition for FcγReceptor (FcγR) binding with immune complexes might interfere with the removal of opsonized microbial agents more than it favoured their opsonophagocytosis. Methods : Using a sensitive FACS-based phagocytosis assay allowing for the identification of the phagocytosing cell-type, we have tested the relative capacity of Pentaglobin® and two investigational IVIg preparations, IVIgG and IVIgM, to promote E. coli phagocytosis. The plasma IL-8 levels 4 h after phagocytosis were measured by ELISA. Results : Heat inactivated, complement (C) depleted serum allowed about 25% polymorphonuclear leukocytes (PMNLs) and 15% monocytes (MNs) of 16 donors to phagocyte E. coli . The addition of IVIg favoured mean phagocytosis by MNs to 55%, but by PMNLs only to 25%. The addition of fresh autologous plasma as a C source resulted in a boost of phagocytosing capacity to reach >90% of the PMNLs and >72% of the MNs. Blockade of FcγRII and FcγRI using monoclonal antibodies (mAb) reduced phagocytosis and IL-8 release. Conclusion : We conclude that excess IVIgG/M preparations added to a phagocytic system of PMNLs and MNs, without preopsonization of E. coli , promotes phagocytosis as expected, but MNs rather than PMNLs do this more thoroughly on their own.

Extracorporeal immunoabsorption for removal of anti-Galalpha1-3Gal (anti-Gal) antibodies in putative pig-to-human xenotransplantation is considered a major prophylactic measure to avoid hyperacute and acute vascular rejections. However, the efficacy of the procedure does depend on choosing the appropriate oligosaccharide epitopes for the binding of human anti-Gal. The synthetic oligosaccharides Galalpha1-3Gal (B-disaccharide, Bdi) and Galalpha1-3Galbeta1-4Glc ('type 6' trisaccharide, Tri6), covalently coupled to Sepharose via polyacrylamide (Sorbents Bdi and -Tri6, respectively), as well as a mixture thereof (Sorbent Mix), were examined for their efficacy to absorb anti-Gal from 20 human serum samples. Sorbent Bdi removed 81% of anti-Gal IgM and 85% of -IgG when assessed on Bdi by ELISA, but only 49% of IgG and 75% of IgM when assessed on Tri6. Sorbent Tri6 and -Mix showed significantly better absorption capacities in so far as Sorbent Tri6 removed 65% of anti-Gal IgM and 80% of -IgG as assessed on Bdi and 85% of IgM/87% of IgG when tested on Tri6, and Sorbent Mix absorbed > 90% anti-Gal of both isotypes of either specificity. Direct hemagglutination of rabbit erythrocytes (ER) was reduced by 75% (median value, range 0-94%) and the median cytotoxicity to PK15 target cells by > 94% after absorption on Sorbent Mix. Neither the decrease in ER agglutination titers nor the reduction of PK15 cytotoxicity revealed significant differences between the three immunoabsorbents tested. The large variation ranges of absorption efficacies within the 20 tested sera suggest that "tailor-made" immunoabsorption treatments may be needed for putative xenotransplant recipients.

The natural occurrence of complement-activating anti-Galalpha1-3Gal antibodies (anti-Gal) in human serum is considered as a major obstacle to xenotransplantation. In this study we determined anti-Gal in sera of 200 healthy volunteers (100 male, 100 female) of different age groups using an IgG- and IgM-isotype specific ELISA. In addition, we used a direct hemagglutination test involving rabbit erythrocytes (E(R)), which are known for abundant surface expression of the Galalpha1-3Gal antigen. The measured arbitrary ELISA units (U) for anti-Gal ranged from 5 to 204 U (77+/-47; mean +/- 1 SD) for IgM, and from 1 to 162 U(73+/-32) for IgG. Anti-E(R) hemagglutination titers were between 1: 65536 and 1: 64 (mean 1: 703), with 75% of all serum samples being in the range of 1: 8192-1: 512. Specificity of the tests was determined by immunoabsorption of anti-Gal on Sepharose-coupled synthetic Galalpha1-3Gal antigen, which reduced ELISA as well as agglutination titers by 90% or more. Overall, inter-individual differences of both anti-Gal ELISA values and E(R) agglutination titers exceeded age-, gender-, or ABO-type related changes. A tendency was found to higher anti-Gal IgM values in women than in men (P < 0.005 by Student's t-test), whereas the gender-difference for anti-Gal IgG or E(R) titers was not significant. Application of the anti-Gal ELISA as well as the E(R) agglutination assay for pre-transplant screening of potential pig xenograft recipients is discussed.

An important antiinflammatory mechanism of intravenous immunoglobulin preparations (IVIG) is their ability to block complement activation. The purpose of this study was to compare the complement-inhibitory activity of four IVIG preparations differing in isotype composition. The preparations were: (1) IVIgG (48 g/L IgG, 2 g/L IgA; Intraglobin F); (2) Pentaglobin (38 g/L IgG, 6 g/L IgM, 6 g/L IgA); (3) IVIgM (35 g/L IgM, 12 g/L IgA, 3 g/L IgG); and (4) IVIgA (41 g/L IgA, 9 g/L IgG), all from Biotest Pharma GmbH, Dreieich, Germany. Their complement inhibitory activity was assessed in vitro by measurement of the blocking of C1q-, C4-, and C3 deposition on solid-phase aggregated rabbit IgG by enzyme-linked immunosorbent assay (ELISA). Complement inhibition in this ELISA was best for IVIgM, followed by Pentaglobin and IVIgG; IVIgA did not exhibit an inhibitory effect. Control experiments with excess concentrations of C1q as well as with C1q-depleted serum showed that the inhibitory effects of IVIG were not caused by complement activation and thus, consumption, but that C4 and C3 were scavenged by IgM and to a lesser extent by IgG. These results were confirmed in vivo in the rat anti-Thy 1 nephritis model, in which a single dose of 500 mg/kg of IVIgM prevented C3-, C6-, and C5b-9 deposition in the rat glomeruli, whereas the effect of IVIgG was much less pronounced. Reduction of complement deposition was paralleled by a diminished albuminuria, which was completely absent in the IVIgM-treated rats. IVIgM and to a lesser extent IVIgG also prevented rat C3 deposition on cultured rat glomerular mesangial cells in vitro, but did not influence anti-Thy 1 binding. Neither IVIgM nor Pentaglobin nor IVIgG negatively affected in vitro phagocytosis of Escherichia coli (E coli) by human granulocytes. In conclusion, we have shown that IgM enrichment of IVIG preparations enhances their effect to prevent the inflammatory effects of complement activation.

Nucleic acid test (NAT) hepatitis B virus (HBV) screening for all blood donations with a sensitivity limit of 25 IU/mL in the individual donation is mandatory in Switzerland since 2009. The aims of the two studies were to define the percentage of antibody to hepatitis B core antigen (anti-HBc) or anti-HBc and antibody to hepatitis B surface antigen (anti-HBs)-positive donors bearing HBV DNA and to gather HBV viral load data on HBV NAT yields during the routine screening since the introduction of the HBV NAT.Archive samples from anti-HBc-positive donors (Group I) were analyzed with a quantitative HBV DNA test and further with anti-HBc and anti-HBs assays. In addition, all the HBV NAT-only-yield samples (Group II) from the routine donor screening performed between July 2007 and May 2013 were included in the study.From the 667 samples investigated (131 donors), three donors (2.3%) had donated eight samples (1.2%) with detectable HBV DNA; however, all had very low viral loads (≤ 10 IU/mL). From the 1,160,426 donations screened with the routine HBV NAT assay, 16 HBV NAT yields were detected: two window period (WP) and 14 occult hepatitis B infection (OBI) cases. In eight of these positive donations (two WP and six OBI), the HBV viral loads were not more than 10 IU/mL, in three cases between 10 and 25 IU/mL, and in the remaining five donations between 37 and 166 IU/mL.The highly sensitive HBV NAT assay with a threshold significantly below 10 IU/mL is a valuable alternative to anti-HBc and a less sensitive HBV NAT screening in blood donor screening.

The risk of transfusion-transmitted hepatitis B virus (HBV) in Switzerland by testing blood donors for hepatitis B surface antigen (HBsAg) alone has been historically estimated at 1:160,000 transfusions. The Swiss health authorities decided not to introduce mandatory antibody to hepatitis B core antigen (anti-HBc) testing but to evaluate the investigation of HBV nucleic acid testing (NAT).Between June 2007 and February 2009, a total of 306,000 donations were screened routinely for HBsAg and HBV DNA by triplex individual-donation (ID)-NAT (Ultrio assay on Tigris system, Gen-Probe/Novartis Diagnostics). ID-NAT repeatedly reactive donors were further characterized for HBV serologic markers and viral load by quantitative polymerase chain reaction. The relative sensitivity of screening for HBsAg, anti-HBc, and HBV DNA was assessed. The residual HBV transmission risk of NAT with or without anti-HBc and HBsAg was retrospectively estimated in a mathematical model.From the 306,000 blood donations, 31 were repeatedly Ultrio test reactive and confirmed HBV infected, of which 24 (77%) and 27 (87%) were HBsAg and anti-HBc positive, respectively. Seven HBV-NAT yields were identified (1:44,000), two pre-HBsAg window period (WP) donations (1:153,000) and five occult HBV infections (1:61,000). Introduction of ID-NAT reduced the risk of HBV WP transmission in repeat donors from 1:95,000 to 1:296,000.Triplex NAT screening reduced the HBV WP transmission risk approximately threefold. NAT alone was more efficacious than the combined use of HBsAg and anti-HBc. The data from this study led to the decision to introduce sensitive HBV-NAT screening in Switzerland. Our findings may be useful in designing more efficient and cost-effective HBV screening strategies in low-prevalence countries.

Galalpha1-3Gal (anti-Gal), a polyclonal so-called natural antibody (Ab), is present in large amounts in human serum not only as IgG-, but also as IgM- and IgA-isotypes. It has gained a particular interest in the context of xenotransplantation, because the endothelial pig cells express the terminal Galalpha1-3Gal determinant on several adhesion molecules. Little is known of it's function and direct examination of the structure of the Ig genes responsible for coding anti-Gal is lacking. We used the technique of isoelectric focussing (IEF)/affinity immunoblotting for direct analysis of the clonal distribution and spectrotype analysis of IgM- and IgG anti-Gal. By single cell analysis of magnetic bead and fluorescent-activated cell sorter (FACS) isolated mature anti-Gal bearing human B cells from whole blood we analyzed the VH gene families involved in anti-Gal production. Oligoclonal and individually distinct IgG banding patterns were found with isoelectric points between 4 and 9. IgM spectrotypes revealed to be more uniform with a polyclonal banding pattern of more than 12 bands at a pH between 4.7 and 7. IgG- and IgM-banding patterns over a period of 6 months remained unchanged. Single cell polymerase chain reaction (PCR), with all family specific primers, revealed the use of the VH2f gene family for the IgG2 isoptype. The differences found in the spectrotype banding patterns of IgG and IgM could be explained by the suggestion that anti-Gal IgM were produced by the use of unmutated germline genes and the possibility of the absence of somatic mutations. The greater clonal heterogeneity in the IgG population could be explained by somatic hypermutations during the switch from IgM to IgG. The use of this VH2f gene family, which is also involved in the generation of Abs against bacterial pathogens, could mean that this is a predominant region used for the generation of such natural occurring antibodies.