English Blood Donors Research Articles

Ultrasensitive PCR system for HBV DNA detection: Risk stratification for occult hepatitis B virus infection in English blood donors.

Occult hepatitis B (HBV) infection (OBI), characterized by low viral loads, accounts for much of the risk of HBV transfusion-transmitted infection. With anticore antibodies (anti-HBc) screening introduced in England, the imperative to identify OBI donors has increased. We aimed to develop an ultra-sensitive PCR system and investigate risk factors for HBV DNA presence in blood donations. Seven extraction methods and three PCR assays were compared. The optimal system was sought to determine HBV DNA presence in anti-HBc-positive donations. Predictors of DNA positivity were subsequently investigated. Extraction from 5 mL of plasma increased sample representation and resulted in HBV DNA detection in low viral load samples (~0.5 IU/mL). Screening of 487 763 donations in 2022 identified two OBI donors and 2042 anti-HBc-positive donors, 412 of the latter with anti-HBs < 100 mIU/mL. Testing of 134 anti-HBc-positive donations utilizing the 5 mL extraction method identified two further HBV DNA-positive donations. Higher anti-HBc titer and anti-HBs negativity were significant predictors of DNA detectability in anti-HBc-positive donations. An ultrasensitive PCR assay identified potentially infectious donations increasing HBV DNA detection in anti-HBc-positive donors from 0.5% to 1.9%. Anti-HBc titers may further complement the risk stratification for DNA positivity in anti-HBc screening and minimize unnecessary donor deferral.

Impact of COVID-19 Vaccination Program on Seroprevalence in Blood Donors in England, 2021

The COVID-19 vaccination programme commenced in the UK on 8th December 2020 primarily based on age; by 24 February 2021 approximately 93% of the English population aged 70-79 years had received at least 1 dose of either the Pfizer BioNTech or AstraZeneca vaccines. Using a nucleoprotein assay that detects antibodies following natural infection only and a spike assay that detects both infection and vaccine-induced responses, we aim to describe the impact of vaccination on SARS-CoV-2 antibody prevalence in English blood donors.

Hepatitis E virus in blood donors in England, 2016 to 2017: from selective to universal screening.

IntroductionHepatitis E virus (HEV), the most common cause of acute hepatitis in many European countries, is transmitted through consumption of processed pork but also via blood transfusion and transplantation. HEV infection can become persistent in immunocompromised individuals.AimWe aimed to determine the incidence and epidemiology of HEV infection in English blood donors since the introduction of donation screening in 2016.MethodsBetween March 2016 and December 2017, 1,838,747 blood donations were screened for HEV RNA. Donations containing HEV RNA were further tested for serological markers, RNA quantification and viral phylogeny. Demographics, travel and diet history were analysed for all infected donors.ResultsWe identified 480 HEV RNA-positive blood donations during the 22-month period, most (319/480; 66%) donors were seronegative. Viral loads ranged from 1 to 3,230,000 IU/ml. All sequences belonged to genotype 3, except one which likely represents a new genotype. Most viraemic donors were over 45 years of age (279/480; 58%), donors aged between 17 and 24 years had a seven-times higher incidence of HEV infection than other donors between March and June 2016 (1:544 donations vs 1:3,830). HEV-infected blood donors were evenly distributed throughout England. Screening prevented 480 HEV RNA-positive blood donations from reaching clinical supply.ConclusionHEV screening of blood donations is a vital step in order to provide safer blood for all recipients, but especially for the immunosuppressed. The unusually high rates of HEV infection in young blood donors may provide some insight into specific risks associated with HEV infection in England.

HLA-A, -B and -C allele and haplotype frequencies defined by next generation sequencing in a population of 519 English blood donors

Whole gene next generation sequencing was used to determine the HLA class I haplotype and allele frequencies in a cohort of 519 English blood donors. This is the first report of HLA frequencies at third field resolution in a UK population with a total of 33, 52 and 30 alleles identified for HLA-A, -B and -C, respectively. Of the 1411 haplotypes determined, 281 had a frequency of greater than 0.05%. Data are available from the Allele Frequencies Net Database under the population name ‘England Blood Donors of Mixed Ethnicity’, identifier 3392.

Hepatitis E Viraemia in Transplant Recipients

▪Introduction:Hepatitis E Virus (HEV) is one of the leading causes of acute infectious hepatitis worldwide; while usually a self-limiting, sub-clinical illness, genotype 3 HEV infection may become chronic in immunosuppressed patients such as solid organ transplant (SOT) or haematopoietic stem cell transplant (HSCT) recipients and rapid progression to cirrhosis may occur. Recent seroprevalence from screening of English blood donors shows antibody prevalence of ~13%. RNA prevalence in donors has increased in the UK from 1:2850 to 1:1460 over the past 3 years. This study examines the point-prevalence of HEV in SOT and HSCT recipients transplanted between January 2013 - December 2015 at a major UK transplant centre. Data on HEV clearance rates and risk factors for infection were collected in the patient cohort.Methods:Stored extracts of blood from patients undergoing liver transplant (OLT), renal transplant (RT) or HSCT were tested by real-time reverse-transcriptase polymerase chain reaction for HEV RNA. Samples were tested at baseline, 30, 60 and 90 days post-transplant +/- 7 days. Time points were chosen to give good coverage of the early post-transplant period whilst avoiding a patient becoming viraemic and clearing the infection between sample time points. All positive samples were sent to the Public Health England reference laboratory for verification, viral RNA genotyping and quantification. Patients with confirmed positive samples underwent further testing and evaluation of clinical parameters to determine chronology of infection, blood product exposure, organ function and histopathology results.Results:259 HSCT, 262 OLT and 349 RT patients met the inclusion criteria. Of the HSCTs there were 111 allogeneic stem cell transplants, 145 autologous transplants and 3 CD34 "top ups". The OLTs comprised 259 deceased donor, 2 live donor and 2 domino liver transplant patients. The RTs comprised 241 deceased donor, 38 live unrelated, 63 live related transplants and 1 live transplant where the relationship of the donor was unrecorded. In total 4 patients (1 HSCT and 3 OLT) were found to have HEV viraemiain our study period. This represents 0.39% of the HSCT and 1.15% of the OLT patients. All were positive with HEV genotype 3.Virologicaland clinical data regarding these patients are presented in tables below.Conclusion:Chronic HEV, genotype 3 in transplant patients is associated with significant morbidity. With the increasing incidence of HEV, immunosuppressed patients with high transfusion burden have an infection risk equivalent to 7-9 years' dietary exposure.Our results show that prevalence of HEV viraemia in OLT, RT and HSCT patients is higher than expectedbased on comparison from UK blood donors. Secondly, infection is not cleared as would be expected in the general population with 3 of the 4 patients requiring treatment to clear the virus.The source of infection for these patients is unclear; on a population wide basis HEV is usually a dietary acquired infection, with pork products carrying the greatest risk. In the transplant patient population, the risk of iatrogenic infection via infected blood products or an infected transplanted organ is an important consideration and UK guidance has recently changed so that transplant recipients receive dietary advice and HEV-negative blood to avoid infection (SaBTO2016).In this study 2 patients were found to be positive for HEV RNA in the baseline sample. One, the recipient of HSCT, did not acquire it through transfusion as testing of the transfused products that the patient had received were negative for the virus. It is not clear how the two OLT patients who tested positive acquired the virus. The absence of any positive results in the renal transplant recipients may reflect the lower transfusion burden in this patient group. Given the multiple routes of possible infection with HEV, a strategy if screening recipients for the virus in addition to screening blood and organ donors would be an effective way of detecting viral transmission via all routes. [Display omitted] [Display omitted] DisclosuresSekhar:Novartis: Research Funding.

Consequences of screening English blood donors for HHV‐8 antibodies. Is it worth it?

BackgroundHuman herpesvirus 8 (HHV‐8) is the causative agent of Kaposi's sarcoma which is of concern in organ transplantation due to transmission through either the donor organ or any associated blood components to immunologically susceptible patients. The prevalence of HHV‐8 in the UK has not been widely investigated. In this study, the seroprevalence of HHV‐8 in English blood donors was measured and the performance of confirmatory assays evaluated.Materials and MethodsDonation samples from 5009 English blood donors were screened for antibodies to HHV‐8. A combination of four different serological and molecular assays was used to investigate any IgG reactivity identified.ResultsHHV‐8 repeatable serological reactivity in English blood donors was 0·7% but could not be confirmed as specific due to a lack of concordance in the confirmatory assays.ConclusionsThese results suggest that the seroprevalence of HHV‐8 is extremely low amongst English donors. These data confirm findings from other studies which suggest a poor predictiveness of HHV‐8 serological assays, especially when used to screen asymptomatic populations. Where a change in donor demography can be anticipated in the UK, further seroprevalence studies should be considered, but only after careful evaluation and selection of the screening and confirmatory assays used.

The tumor necrosis factor polymorphism TNF (−308) is associated with susceptibility to meningococcal sepsis, but not with lethality*

To determine whether the promoter polymorphism tumor necrosis factor (TNF) (-308) is associated with susceptibility to or death from meningococcal sepsis. DESIGN, SETTING, PATIENTS, AND PARTICIPANTS: Association study involving 1321 patients with microbiologically proven invasive meningococcal disease presenting to hospitals throughout United Kingdom during 1998-2001, among whom 134 died. Controls were derived from 1280 northern English blood donors. DNA from patients and controls was genotyped at TNF (-308). After analysis, DNA was subsequently genotyped at eight other markers in strong linkage disequilibrium with TNF (-308); these markers were IkappaBL (-62), BAT3, LST1, NOTCH4 (+1297), NOTCH4 (+3061), CCHCR1 (+436), CCHCR1 (+2271), and LTalpha. To confirm functional relevance of TNF (-308) in the context of meningococcal disease, TNF secretion by, and TNF messenger RNA expression of macrophages derived from volunteers with known TNF (-308) genotype after exposure to Neisseria meningitidis were measured. Among cases of meningococcal disease, likelihood of death was shown to be influenced by the age of the affected individual and also with the infecting serogroup, but was not influenced by genotype at TNF (-308) or the other linked markers. However, patients with meningococcal disease, irrespective of whether they died, were more likely to be homozygous for the rare allele at TNF (-308) (odds ratio = 1.93, 95% confidence interval 1.08-3.46), and less likely to be heterozygous for this marker (odds ratio = 0.79, 95% confidence interval 0.64-0.97), compared with the control cohort. There was no association of susceptibility to disease with the other markers studied. Macrophages derived from volunteers homozygous for the rare allele at TNF (-308) expressed higher levels of TNF messenger RNA and secreted higher concentrations of TNF compared with common homozygotes after exposure to N. meningitidis. Genotype at TNF (-308) modifies cellular TNF secretion in response to N. meningitidis and may influence susceptibility to meningococcal disease, but does not influence the likelihood of death after infection.

Variation in Toll-like receptor 4 and susceptibility to group A meningococcal meningitis in Gambian children.

Meningitis is an important cause of childhood mortality in sub-Saharan Africa. A case-control study investigating the role of the Toll-like receptor 4 gene in host susceptibility to Group A Neisseria meningitidis meningitis was conducted in 524 Gambian children. There was no association between a functional Toll-like receptor 4 gene polymorphism and meningitis, suggesting that this variant is not a major determinant of disease in this population.

Haemochromatosis-associated HFE genotypes in English blood donors: age-related frequency and biochemical expression

Background/Aims: There are limited data on the frequency and biochemical expression of the haemochromatosis-associated mutations C282Y and H63D in healthy people. Methods: We genotyped (bi-directional PCR amplification of specific alleles method) and performed serum iron studies in randomly selected English male blood donors (<4 previous units donated) in four age bands <30, 30–40, 40–50 and >50 years. Results: In 6261 subjects, frequency of C282Y homozygosity (+/+) was 0.3%, C282Y/H63D compound heterozygosity (+/−) 2.0%, and H63D and C282Y heterozygosity +/−, 21.7 and 10.4%, respectively. Genotype distribution was within Hardy–Weinberg equilibrium in each age band. C282Y +/− frequency fell from 11.7% in subjects <30 years to 8.2% in subjects >50 (Chi 2 7.19; P<0.005). No such trend was seen for C282Y +/+. In C282Y +/+ subjects, median serum ferritin was 247 (range 60–2449) μg/l and exceeded >500 μg/l in only two of 18 subjects. Compared to wild/wild (−/−) subjects, C282Y and H63D +/− subjects had slightly higher serum iron and lower unsaturated iron binding concentrations, similar overall serum ferritin values but higher serum ferritin values in subjects who had previously donated blood. Conclusions: C282Y +/+ shows limited biochemical expression and no trend towards age-related attrition. C282Y and H63D +/− may protect against iron deficiency.

Iron and the Genetics of Cardiovascular Disease

The hypothesis that iron depletion protects against ischemic heart disease was proposed in 1981 as an explanation for the sex difference in heart disease rates.1 2 3 4 5 The “iron hypothesis” has generated significant debate, especially in the 1990s after publication of supportive findings from Finland.6 Confusion has been introduced into the debate by inappropriate study designs in tests of the hypothesis. A recurring weakness is that stored iron is measured by inappropriate methods. In addition, evidence against a particular mechanism may be erroneously taken as evidence against the core hypothesis. For example, in a particular study design, a finding of no association of stored iron with coronary atherosclerosis would not invalidate an association of stored iron with cardiovascular mortality. Recent studies relevant to the iron hypothesis have been reviewed.5 7 8 9 10 11 12 In 1994, Ascherio and Willett13 recognized that the iron hypothesis cannot be rejected on the basis of available data, stating that “[s]tronger evidence is needed before the hypothesis is rejected that greater iron stores increase the incidence of coronary heart disease or death from myocardial infarction.” Indeed, nothing in data made available since 1994 excludes the possibility that iron depletion has a large protective effect, large enough to explain the low incidence of myocardial infarction in menstruating women. A 1997 editorial14 on the iron hypothesis suggests that this once-controversial idea has become more acceptable to many scientists. Gillum14 noted that “this important hypothesis and related research fronts have led to many valuable studies like that of Kiechl et al [see Reference 99 ], which will greatly enhance our understanding of atherosclerotic vascular disease and may lead to innovations useful in clinical medicine and public health, perhaps in heretofore unanticipated ways.” Mechanisms of protection have not been …

Incidence of seroconversion to positivity for hepatitis C antibody in repeat blood donors in England, 1993-5

Objective: To estimate the rate of seroconversion to positivity for hepatitis C antibody in repeat blood donors in England and to describe the probable routes of infection in these donors.Design:...

A new low-frequency antigen BOW (Bowyer).

BOW is a 'new' low-frequency red-cell antigen, detected in 2 unrelated English blood donors, that is sensitive to alpha-chymotrypsin and pronase. Anti-BOW is present in many polyspecific reagents used to define low-frequency antigens. Red-cell groups of the proposita, R.B., and her family show that the BOW blood group segregates independently from the ABO, Rh, MNSs, P1 and Kell blood group systems.

MER2: a red cell polymorphism defined by monoclonal antibodies.

Two murine monoclonal antibodies, 1D12 and 2F7, apparently of the same specificity, define a new red cell polymorphism, MER2. 92% of English blood donors are MER2+ giving the gene frequencies MER2+ 0.7159; MER2- 0.2841. Family studies showed that MER2+ is inherited as a Mendelian dominant character and that MER2 is not controlled by any of the main blood group loci. The MER2 antigen is also present on some leukaemia fibroblasts and human cell lines. Using somatic cell hybrids, MER2 appears to be coded for by a gene on chromosome 11 at 11p15.

Screening of blood donors for IgA deficiency: a study of the donor population of south-west England.

Altogether 29 745 English blood donors were screened for IgA deficiency by double diffusion analysis; 57 had apparent absence of IgA, a frequency of 1:522. Further examination by the more sensitive haemagglutination inhibition assay revealed 34 samples having no detectable IgA, a frequency of 1:875. All donors negative by double diffusion analysis were tested for the presence of antibodies to IgA. Six class specific anti IgA antibodies and four anti IgA antibodies of limited specificity were detected. Three of these had the specificity anti alpha2 and one anti A2m(2). The 34 IgA deficient donors detected provide a source of IgA deficient blood for transfusion to patients with anti IgA antibodies.

Wka (Weeks), a new antigen in the Kell blood group system.

Abstract. An immune antibody, made in response to transfusion, has revealed a new antigen (Wka) with a frequency of 0.3% among English blood donors, and 0.1% among K+ blood donors. The families of 5 K+ Wk(a+) propositi have no recombinants and 13 non‐recombinants. The new antigen is shown to be part of the Kell blood group system.

Wk^a (Weeks), a New Antigen in the Kell Blood Group System

An immune antibody, made in response to transfusion, has revealed a new antigen (Wk^a) with a frequency of 0.3% among English blood donors, and 0.1% among K+ blood donors. The families of 5 K+ Wk(a+) propositi have no recombinants and 13 non-recombinants. The new antigen is shown to be part of the Kell blood group system.