Effective serological and molecular screening of deceased tissue donors.

A comprehensive and effective screening programme is essential to support the banking of tissues from deceased donors. However, the overall quality of the samples obtained from deceased donors, quantity and condition, is often not ideal, and this may lead to problems in achieving accurate and reliable results. Additionally a significant percentage of referrals are still rejected upon receipt as unsuitable for screening. We are actively involved in improving the overall quality of deceased donor screening outcomes, and have specifically evaluated and validated both serological and molecular assays for this purpose, as well as developing a specific screening strategy to minimise the specificity issues associated with serological screening. Here we review the nature and effectiveness of the deceased donor screening programme implemented by National Health Service Blood and Transplant (NHSBT), the organisation with overall responsibility for the supply of tissue products within England. Deceased donor screening data, serological and molecular, from August 2007 until May 2012 have been collated and analysed. Of 10,225 samples referred for serology screening, 5.5 % were reported as reactive; of 2,862 samples referred for molecular screening, 0.1 % were reported as reactive/inhibitory. Overall 20 % of the serological and 100 % of the molecular screen reactivity was confirmed as reflecting true infection. The use of a sequential serology screening algorithm has resulted in a marked reduction of tissues lost unnecessarily due to non-specific screen reactivity. The approach taken by NHSBT has resulted in the development of an effective and specific approach to the screening of deceased tissue donors.

Qualification of serological infectious disease assays for the screening of samples from deceased tissue donors.

Whilst some of the assays used for serological screening of post-mortem blood samples from deceased tissue donors in some countries have been specifically validated by the manufacturer for this purpose, a significant number of those currently in use globally have not. Although specificity has previously been considered a problem in the screening of such samples, we believe that ensuring sensitivity is more important. The aim of this study was to validate a broader range of assays for the screening of post-mortem blood samples from deceased tissue donors. Six microplate immunoassays currently in use within National Health Service Blood and Transplant (NHSBT) for the screening of blood, tissue and stem cell donations were included. Representative samples from confirmed positive donors were titrated in screen negative post-mortem samples in parallel with normal pooled negative serum to determine if there was any inhibition with the post-mortem samples. There were no significant differences seen (P < 0.005) between the dilution curves obtained for the positive samples diluted in post-mortem samples and normal pooled sera. Although small numbers of samples were studied, it can be surmised that the post-mortem blood samples from deceased tissue donors, collected according to United Kingdom guidelines, are a suitable substrate for the assays evaluated. No diminution of reactivity was seen when dilution with sera from deceased donors was compared to dilution using pooled serum from live donors. In the absence of genuine low titre positive post-mortem samples, the use of samples spiked with various levels of target material provides a means of qualifying serological screening assays used by NHSBT for the screening of post-mortem blood samples from deceased tissue donors.

Lot release testing of serological infectious disease assays used for donor and donation screening.

BACKGROUND AND OBJECTIVES: Monitoring of the ongoing performance of infectious disease screening assays is a critical part of any donation screening programme. Although assay sensitivity is formally evaluated prior to implementation, it is essential that this level of performance is maintained from lot-to-lot. In 2002, National Health Service Blood and Transplant developed and implemented a formal system for the lot release testing of serology infectious disease screening assays. MATERIALS AND METHODS: Lot release panels were prepared for each of the serological screening markers. They each comprise 10-15 members and include both genuine low-titre and diluted high-titre materials. For each panel member, a minimum reactivity is expected, based upon the formal sensitivity evaluation of each assay. All new lots of the screening assays used are assessed prior to supply of the lot to the organization. RESULTS: Since 2002, a total of 887 different lots of the serology screening assays used have been supplied. Of these, 876 (98.8%) passed lot release and were authorized for supply to the organization. Eleven lots (1.2%) were failed because the lots did not meet the release criteria or were unsuitable for some other reason. CONCLUSION: The lot release system has proved to be effective in objectively assessing assay performance to ensure that there is no significant lot-to-lot variation such that the performance of the assay may fall below that originally determined at evaluation. The few assays that have failed lot release did have proven performance issues that were subsequently accepted by the manufacturers. CONTENTS SUMMARY: Description of the Lot Release Testing system for serology infectious disease screening assays in use within NHSBT with a critical analysis and review of the data generated in the 7 years that the system has been in use.

A national survey of genitourinary medicine clinic attenders provides little evidence of sexual transmission of hepatitis C virus infection.

OBJECTIVE: To determine the prevalence and genetic diversity of hepatitis C virus in genitourinary medicine clinic attenders and to assess the extent of sexual transmission of the virus. METHODS: A cross sectional, unlinked, anonymous survey in 14 genitourinary medicine clinics situated in England, Wales, and Northern Ireland. Serum specimens from genitourinary medicine clinic attenders, retained as part of the Unlinked Anonymous Prevalence Monitoring Programme (UAPMP) serum archive, were tested in small pools, for the presence of antibody to hepatitis C virus (anti-HCV). The main outcome measures were prevalence of antibodies to hepatitis C virus and identification of hepatitis C virus genotypes. RESULTS: Testing of 17,586 specimens from 1995 showed an adjusted prevalence of anti-HCV in genitourinary medicine clinic attenders of 1.03% (95% CI: 0.89 to 1.16) overall and 0.65% (95% CI: 0.51 to 0.78) among those who did not report injecting drug use. Prevalence in injecting drug users attending genitourinary medicine clinics was 36.9% in both 1995 and 1996. Heterosexual injecting drug users had a higher prevalence of anti-HCV than homosexual/bisexual injectors. The most common hepatitis C genotypes were types 3a and 1a. There was a high degree of concordance between genotype and serotype. CONCLUSIONS: The low prevalence of anti-HCV in genitourinary medicine clinic attenders who deny injecting drugs suggests that the majority of hepatitis C infections have been acquired in adult life, mostly by injecting drug use, and that the hepatitis C virus is rarely transmitted sexually. The use of needle exchanges may explain the relatively low prevalence observed in the injecting drug users.

The prevalence and genetic diversity of hepatitis C infection in antenatal clinic attenders in two regions of England.

The prevalence and genetic diversity of hepatitis C infection in women attending antenatal clinics in two regions of England was investigated to inform future surveillance and control measures. Women booking into antenatal care are routinely offered a test for immunity to rubella. Serum residues from these tests were unlinked, anonymized and archived as part of the Unlinked Anonymous Prevalence Monitoring Programme (UAPMP). The serum specimens were tested for anti-HCV using a cost-effective pooling strategy. After taking into account differential sampling from the UAPMP serum archive, the adjusted overall prevalence of anti-HCV was 0.43% (95% CI: 0.32-0.53) in London and 0.21% (95% CI: 0.14-0.28) in the Northern and Yorkshire region. Restriction fragment length polymorphism of amplified HCV RNA identified type 3a as the most common HCV genotype in these antenatal women. The prevalence of anti-HCV in antenatal women in the UK is low and consistent with that expected from injecting drug use.

Poor hepatitis B vaccine coverage in injecting drug users: England, 1995 and 1996.

Self-reported data on vaccination status collected in 1995 and 1996 from seven of the 39 drug agencies in England that took part in the unlinked anonymous HIV prevalence monitoring programme of injecting drug users were analysed to estimate hepatitis B vaccine coverage in this population. Twenty-seven per cent (374/1366) of injecting drug users (IDUs) reported vaccination against hepatitis B and 13% (172) reported having received three doses of vaccine. Eighteen per cent of the IDUs who reported vaccination (66/374) were found to have a marker in their saliva of past/current hepatitis B infection (antibody to hepatitis B core (anti-HBc)) compared with 23% (232/992) of those unvaccinated. Over half (760/1366) of all IDUs tested reported not having been vaccinated against hepatitis B were negative for anti-HBc, and therefore remained susceptible to infection. Targeted vaccination for IDUs against hepatitis B in England has had little success so far, suggesting that enhanced or alternative strategies need to be adopted.

The risk of infection with HIV and hepatitis B in individuals who inject steroids in England and Wales.

Data on injecting anabolic steroid users, within the national Unlinked Anonymous HIV Prevalence Monitoring Survey of injecting drug users (IDUs) were analysed to determine their risk of acquiring blood borne viruses. One hundred and forty-nine participants who had injected anabolic steroids in the previous month were identified from 1991-6, contributing 1.4% of all participation episodes in the survey. Rates of needle and syringe sharing by steroid users were low. Three of the 149 (2.0%) had anti-HBc and none had anti-HIV in their salivary specimens. The prevalence of anti-HBc in steroid injectors was significantly lower than in heroin injectors, 275/1509 (18%) (P < 0.001), or in amphetamine injectors, 28/239 (12%) (P < 0.001). The risk of blood borne virus transmission amongst these steroid injectors is low, probably due to hygienic use of injecting equipment and low levels of sharing. It is important to distinguish steroid injectors from other IDUs because they are a distinct group in terms of lifestyle and injecting practice.