Analysis of HBV infection after blood transfusion in Japan through investigation of a comprehensive donor specimen repository

Frequency of hepatitis B virus-DNA among hepatitis B surface-Ag negative, anti-hepatitis B core antibody-positive blood donors in Yazd, Iran

BACKGROUND:

The diagnosis of hepatitis B infection in most blood transfusion centers is based on hepatitis B surface (HBs) antigen detection by an enzyme immunoassay method. This study aimed to determine the frequency of hepatitis B core (HBc) antibody, HBs antibody, and hepatitis B virus (HBV) DNA among HBs antigen-negative healthy blood donors of Yazd province, Iran.

MATERIALS AND METHODS:

This cross-sectional study was conducted on 1500 healthy blood donor samples negative for HBs antigen, hepatitis C virus antibody, human immunodeficiency virus antigen/antibody, and rapid plasma regain tests. All samples were screened for HBc antibody test. HBs antibody and real-time polymerase chain reaction were performed for HBc antibody-positive samples.

RESULTS:

HBc antibody was positive in 74 (4.9%) samples and 11 (14.9%) of 74 positive samples for HBc antibody were negative for HBs antibody. Sixty-three (85.1%) positive samples for HBc antibody had HBs antibody titer over 10 IU/L, and 43 (58.1%) had HBs antibody titer over 100 IU/L. There was no hepatitis B DNA-positive sample in the present study.

CONCLUSIONS:

The study results suggest that there is a very low risk for transmission of HBV through blood donors of Yazd, Iran.

Characteristic of HBV nucleic acid amplification testing yields from blood donors in China

BACKGROUND

Nucleic acid amplification testing (NAT) for blood screening has been previously performed in some countries to determine NAT yields. The current study sought to explore the non-discriminating reactive NAT yields using individual-NAT (ID-NAT) and characteristics of HBV NAT yields through a 10-year retrospective analysis in Zhejiang, China.

METHODS

Blood donations were analyzed using individual-NAT mode by the transcription-mediated amplification (TMA) method. Supplementary HBV serological tests were performed using chemiluminescent immunoassay, and HBV viral load assay was performed by real-time polymerase chain reaction. Follow-up studies were performed in partial donors with low HBV viral loads.

RESULTS

Non-discriminating reactive NAT yields and HBV NAT yields varied in different years. The yields ranged from 853.73 per million to 2018.68 per million and 624.60 per million to 1669.50 per million, respectively. In the 476 NAT yields, 19 were probable window periods (WP), 33 probable occult hepatitis B virus infections (OBIs), 409 were confirmed OBIs and 15 were chronic HBV infections. ID-NAT results were categorized in four groups, and the findings showed that the levels of HBV DNA viral loads were different in the four different groups (χ² = 275.02, p < 0.01). HBV viral load distribution was significantly different between anti-HBs positive and anti-HBc positive samples (χ² = 49.429, p < 0.01). Notably, only 42.03% donors were NAT repeated positive in the 138 repeat donors' follow up tests.

CONCLUSION

NAT screening of blood donations can reduce the risk of transfusion-transmitted HBV infections. Positive proportions of anti-HBs and anti-HBc are correlated with the HBV viral load level. However, low level of viral load donors pose risks in HBV NAT assays, and show fluctuating state for HBV viral load and leads to non-repeated NAT results during follow up studies.

High Frequency Occult Hepatitis B Virus Infection Detected in Non-Resolved Donations Suggests the Requirement of Anti-HBc Test in Blood Donors in Southern China

Background

Most Chinese Blood Centers adopted mini pool (MP) nucleic acid testing (NAT) for HBV screening due to high cost of Individual donation (ID) NAT, and different proportions of MP-reactive but ID-non-reactive donations (MP+/ID-, defined as non-resolved donations) have been observed during daily donor screening process. Some of these non-resolved donations are occult HBV infections (OBIs), which pose potential risk of HBV transmission if they are not deferred. This study is aimed to further analyze these non-resolved donations.

Methods

The non-resolved plasma samples were further analyzed by serological tests and various HBV DNA amplification assays including quantitative PCR (qPCR) and nested PCR amplifying the basic core and pre-core promoter regions (BCP/PC; 295 base pairs) and HBsAg (S) region (496 base pairs). Molecular characterizations of HBV DNA+ non-resolved samples were determined by sequencing analysis.

Results

Of 17,226 MPs from 103,356 seronegative blood donations, 98 MPs were detected reactive for HBV. Fifty-six out of these 98 (57.1%) reactive MPs were resolved as HBV DNA+, but the remaining 42 pools (42.9%, 252 donations) were left non-resolved with a high rate (53.2%) of anti-HBc+. Surprisingly, among 42 non-resolved MPs, 17 contained one donation identified as OBIs by alternative NAT assays. Sequence analysis on HBV DNAs extracted from these OBI donations showed some key mutations in the S region that may lead to failure in HBsAg detection and vaccine escape.

Conclusion

A total of 53.2% of the non-resolved donations were anti-HBc+, and OBIs were identified in 40.5% of these non-resolved pools. Therefore, non-resolved donations with anti-HBc+ might pose potential risk for HBV transmission. Our present analysis indicates that anti-HBc testing in non-resolved donations should be used to identify OBIs in order to further increase blood safety in China.

Hepatitis B virus infection and its associated factors among medical waste collectors at public health facilities in eastern Ethiopia: a facility-based cross-sectional study

BACKGROUND

The risk of hepatitis B virus infection among medical waste handlers who undergo collection, transportation, and disposal of medical wastes in the health institutions is higher due to frequent exposure to contaminated blood and other body fluids. There is limited evidence on the seroprevalence of hepatitis B among medical waste handlers in eastern Ethiopia. The study was aimed at studying the seroprevalence of Hepatitis B Virus and associated risk factors among medical waste collectors at health facilities of eastern Ethiopia.

METHODS

A facility-based cross-sectional study was conducted among randomly selected medical waste collectors from public health facilities in eastern Ethiopia from March to June 2018. A pre-tested and well-structured questionnaire was used to collect data on socio-demographic characteristics and hepatitis B infection risk factors. A2.5ml venous blood was also collected, centrifuged and the serum was analyzed for hepatitis B surface antigen using the instant hepatitis B surface antigen kit. Descriptive summary measures were done. Chi-square and Fisher exact tests were used to assess the risk of association. Multivariate logistic regression was conducted with 95% CI and all value at P-value < 0.05 was declared statistically significant.

RESULTS

From a total of 260 (97.38%) medical waste collectors participated, HBV was detected in 53 (20.4%) of the participants [95%CI; 15.8, 25.6]. No significant differences were observed in the detection rates of HBV with respect to socio-demographic characteristics. In both bivariate and multivariable logistic regression analysis, being unvaccinated (AOR = 6.35; 95%CI = [2.53-15.96], P = 0.001), history of blood transfusion (receiving) (AOR; 3.54; 95%CI; [1.02-12.24], P = 0.046), history of tattooing (AOR = 2.86; 95%CI = [1.12-7.27], p = 0.03), and history of multiple sexual partner (AOR = 10.28; 95%CI = [4.16-25.38], P = 0.001) remained statistically significantly associated with HBsAg positivity.

CONCLUSION

This cross-sectional study identified that HBV infection is high among medical waste collectors in eastern Ethiopia. Immunization and on job health promotion and disease prevention measures should be considered in order to control the risk of HBV infection among medical waste collectors in eastern Ethiopia.

Quantification of Transfusion Recipients at Risk of Receiving Hepatitis B Virus-Contaminated Blood Components: A Korean Study

Although there are lots of studies about the risk for the hepatitis B virus infection such as the residual risk for donated blood, there is no research on the risk of HBV infection, from the viewpoint of recipients in Korea. Using the data about HBsAg status of donated blood in 2008 and 2009, the distribution of blood components from the claim data of health insurance in 2009, the distribution of HBsAg and HBsAb of recipients, and some assumptions, we quantified the number of recipients in Korea that might be expected to receive HBV-contaminated blood components, as a proxy index for HBV infection by transfusion in 2009. Of the 376,211 recipients, the number who might be expected to receive blood components with HBV in 2009 was 23.2 (95 % CI 13.6, 36.8) in the basic model, 43.2 (95 % CI 25.4, 68.7) in extended model I, 55.2 (95 % CI 32.5, 87.7) in extended model II and 101.6 (95 % CI 59.8, 161.4) in extended model III. The number of HBV-positive samples per 100,000 transfused units was 0.6 in the basic model (95 % CI 0.3, 0.9), 1.1 in extended model I (95 % CI 0.6, 1.8), 1.4 in extended model II (95 % CI 0.8, 2.2), and 2.6 in extended model III (95 % CI 1.5, 4.1). This study showed that a few recipients might receive HBV-contaminated blood component by transfusion. These results could be used as a scientific evidence for health policy on HBV transfusion infection.

Characterisation and follow-up study of occult hepatitis B virus infection in anti-HBc-positive qualified blood donors in southern China

BACKGROUND

Most major Chinese blood centres look for hepatitis B surface antigen (HBsAg) and perform nucleic acid testing to screen blood for hepatitis B virus infection. The search for antibodies to the core of hepatitis B virus (anti-HBc) has not been implemented because it would lead to a high rate of discarded blood units. The aim of this study was to evaluate the prevalence of occult HBV infection among anti-HBc-positive qualified blood donors in southern China.

MATERIALS AND METHODS

We tested anti-HBc-positive blood donations negative for HBsAg and HBV DNA by standard NAT from Shenzhen for the presence of HBV DNA by sensitive nested and quantitative polymerase chain reactions. Anti-HBs titres were quantified. HBV DNA-positive donors were traced and followed-up.

RESULTS

Of the 1,033 qualified donors, 47.4% (95% CI: 44.4 to 50.5%) carried anti-HBc as evidence of exposure to HBV. The rate of anti-HBc positivity increased steadily with age, ranging from 32.6% in the age group <30 years to 69.8% in the age group <50 years (p<0.001). Of the 1,033 donors, 777 (75.2%; 95% CI: 72.4 to 77.8%) carried anti-HBs (>10 IU/L). HBV DNA was detected in 14 donors who were anti-HBc-positive, HBsAg-negative and negative by routine NAT. Seven of those 14 specimens had an anti-HBs titre above 100 mIU/mL. The prevalence of OBI in anti-HBc-positive qualified blood donors was 2.86% (95% CI: 1.57 to 4.75%). Eight of the 14 OBI cases were genotype B and one was genotype C; 7/14 cases were followed-up, one case converted to anti-HBe. HBV DNA became undetectable in all follow-up samples.

DISCUSSION

A small proportion of anti-HBc-positive qualified donors carry HBV DNA after HBsAg and NAT screening. This finding suggests the possibility of HBV transmission from asymptomatic donors, especially in areas of high HBV prevalence. More sensitive NAT rather than anti-HBc testing should be considered to improve blood safety.

High Prevalence of Hepatitis B Virus Infection in Young Adults in Ternate, Eastern Indonesia

The incidence of hepatitis B virus (HBV) infection has been declining thanks to the universal hepatitis B infant immunization program. Nevertheless, young adults born before the program implementation might have acquired HBV in early childhood or remain susceptible to infection. This study aimed to evaluate hepatitis B epidemiology in asymptomatic young adult population in Ternate, eastern Indonesia. Serum samples of 376 subjects (aged 17-25, mean 19.82 ± 1.69 years; male/female 138/238) were screened for HBV parameters serologically (HBV surface antigen [HBsAg]; its antibody [anti-HBs]; anti-core antigen [anti-HBc]), and molecularly (HBV DNA). HBsAg, anti-HBc, anti-HBs, and HBV DNA prevalence were 15.7%, 36.2%, 24.2%, and 27.9%, respectively, with male predominance. Of all subjects, 13.0% were HBsAg negative with detectable HBV DNA (occult hepatitis B [OHB]), and 56.4% showed negativity for all seromarkers. This population showed high hepatitis B prevalence with substantial occurrence of OHB. However, a high percentage of the population were still susceptible and at risk of HBV infection. This study emphasizes the necessity to improve prevention strategies to screen and manage HBV carriers, including the adoption of catch-up or booster vaccination targeted to young adult populations. Investigations on the roles of host-virus interactions associated with OHB and its implications are warranted.

Seroepidemiology and occult hepatitis B virus infection in young adults in Banjarmasin, Indonesia

Hepatitis B virus (HBV) infection remains a public health problem in Indonesia. There has been limited data regarding HBV infection in young adult population. This study aimed to evaluate the seroepidemiology of HBV infection and characterize occult HBV variants in healthy young adults in Banjarmasin, Indonesia, who were born before the implementation of the universal infant hepatitis B vaccination. Serum samples of 195 healthy young adults were tested for HBsAg, anti-HBc, and anti-HBs. The prevalence of HBsAg, anti-HBc, and anti-HBs was 9 (4.6%), 62 (31.8%), and 96 (49.2%), respectively. Seventy four (37.9%) samples were seronegative for all three parameters, indicating the susceptibility to HBV infection. Among 66 samples positive for HBsAg and/or anti-HBc, 13 (19.7%) were HBV DNA positive; of these, four were HBsAg positive and nine were HBsAg negative, and categorized as occult HBV infection. Most occult HBV cases had high-level anti-HBs (>100 IU/l), suggesting that blood with positive anti-HBs and anti-HBc could not be regarded as noninfectious. Thirteen amino acid substitutions were identified: T126S, P127S, Q129R, T131N, M133T, and Y161S in the HBsAg-positive group; P120T, T126I, G145S, Y161F, E164V, and V168F in the occult-HBV group; and T143S in both groups. More studies are required to provide data on the prevalence and characteristics of mutants to ensure reliable diagnosis. The occult HBV infection, combined with the HBsAg prevalence, could indicate the high HBV carriage among young adults in this area. The high percentage of individuals susceptible to HBV infection reiterates the need for catch-up immunization strategies targeted at young adults.

[Evaluation of HBs Ag, HCV and HIV Ag-Ab Assays using Bio-Rad Elite Microplate Analyzer.]

BACKGROUND

In this study, we evaluated the performance of Elite microplate analyzer (Bio-Rad Laboratories, France) and the related assays (ULTRA line) for the detection of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV).

METHODS

Seroconversion panels, HBsAg positive/HBsAg negative (n=99/n=1,422), anti-HCV positive/negative (n=97/n=1,670), and anti-HIV positive/negative (n=112/n=1,704) samples were used to evaluate the performance of Monolisa HBsAg ULTRA, Monolisa HCV Ag-Ab ULTRA, and Genscreen ULTRA HIV Ag-Ab, respectively. The agreement of Elite microplate analyzer with CODA analyzer (Bio-Rad Laboratories, CA, USA) was also evaluated.

RESULTS

The detection limit of Monolisa HBsAg ULTRA was 0.034 IU/mL. For Monolisa HBsAg ULTRA, Monolisa HCV Ag-Ab ULTRA, and Genscreen ULTRA HIV Ag-Ab, diagnostic sensitivities were all 100%, diagnostic specificities were 100%, 99.8% and 99.9%, and total CVs (coefficients of variation) were 13.8-17.5%, 3.4-5.2%, and 7.5-9.5%, respectively. The agreement of Elite microplate analyzer with CODA analyzer was 99.5%.

CONCLUSIONS

The performance of Elite microplate analyzer and the related assays on analytical sensitivity, precision, early detection, diagnostic sensitivity and specificity was all adequate for a mass screening. However, further large multi-center studies should be performed to validate our results.

New Strategies for Blood Donor Screening for Hepatitis B Virus

Serologic testing for hepatitis B virus (HBV) surface antigen (HBsAg) and antibody to HBV core antigen (anti-HBc) has historically been the foundation of blood screening, while HBV nucleic acid testing (NAT) was recently developed to detect HBsAg-negative, anti-HBc-negative blood units donated during early acute infection. Comparison data on seroconversion panels using HBsAg assays of varying sensitivities and pooled- or single-sample NAT, along with viral load estimates corresponding to HBsAg assay detection limits, have provided information on the theoretical benefits of NAT relative to HBsAg. Model-derived estimates have generally been predictive of the yields of DNA-positive, HBsAg-negative window period blood units detected in a number of studies from Europe, Japan, and the US. Studies indicate that the added benefit of pooled-sample NAT is relatively small in areas of low endemicity, with greater yields in areas highly endemic for HBV. Single-sample NAT would offer more significant early window period closure and could prevent a moderate number of residual HBV transmissions not detected by HBsAg assays; however, no fully automated single-sample HBV NAT systems are currently available.Even single-sample HBV NAT may not substitute for anti-HBc screening, as indicated by studies of donors with isolated anti-HBc who have extremely low DNA levels undetectable by standard single-sample NAT and who have been associated with transfusion-transmitted HBV. Moreover, HBsAg testing may still be needed even in the setting of combined anti-HBc and NAT screening. HBsAg-positive units from donors in the chronic stage of infection may contain very low or intermittently detectable DNA levels that single-sample NAT would miss. Although such donors are usually anti-HBc reactive and would be interdicted by anti-HBc screening, some lack anti-HBc. Extensive parallel testing will be needed to determine whether single-sample NAT in combination with anti-HBc might be sufficient to detect all the infectious donors currently interdicted by HBsAg testing. In countries that do not screen for anti-HBc, HBsAg testing would be the only means of detecting donations from chronically infected individuals with low/intermittently detectable DNA, since even single-donor NAT would not identify these potentially infectious blood units. In the future, the current fully automated HBsAg assays may incorporate significant sensitivity improvements, and automated single-sample HBV NAT may become a reality. Each country will need to develop its blood screening strategy based on HBV endemicity, yields of infectious units detected by different serologic/NAT screening methods, and cost effectiveness of test methods in ensuring blood safety.

Hepatitis B virus transmission by blood transfusion during 4 years of individual-donation nucleic acid testing in South Africa: estimated and observed window period risk

BACKGROUND

Since October 2005, a total of 2,921,561 blood donations have been screened by the South African National Blood Service for hepatitis B virus (HBV) by individual-donation nucleic acid testing (ID-NAT). Over 4 years, 149 hepatitis B surface antigen-negative acute-phase HBV NAT-positive donations were identified (1:19,608). The lookback program identified one probable HBV transmission.

STUDY DESIGN AND METHODS

The complete genomes of HBV isolated from the donor and recipient were sequenced, cloned, and analyzed phylogenetically. The HBV window period (WP) transmission risk was estimated assuming a minimum infectious dose of 3.7 HBV virions and an incidence rate correction factor of 1.34 for transient detectability of HBV DNA.

RESULTS

Of 149 acute-phase HBV NAT yields, 114 (1:25,627) were classified as pre-antibody to hepatitis B core antigen (anti-HBc) WP and 35 (1:83,473) as post-anti-HBc WP. The acute-phase transmission risk in the HBV DNA-negative pre- and post-anti-HBc WPs (of 15.3 and 1.3 days, respectively) was estimated at 1:40,000 and 1:480,000, respectively. One HBV transmission (1:2,900,000) was identified in a patient who received a transfusion from an ID-NAT-nonreactive donor in the pre-anti-HBc WP. Sequence analysis confirmed transmission of HBV Subgenotype A1 with 99.7% nucleotide homology between donor and recipient strains. The viral burden in the infectious red blood cell unit was estimated at 32 (22-43) HBV DNA copies/20 mL of plasma.

CONCLUSION

We report the first known case of transfusion-transmitted HBV infection by blood screened using ID-NAT giving an observed HBV transmission rate of 0.34 per million. The estimated pre-acute-phase transmission risk in the ID-NAT screened donor population was 73-fold higher than the observed WP transmission rate.

Reducing the risk of hepatitis B virus transfusion-transmitted infection

Before 1970, approximately 6% of multi-transfused recipients acquired a transfusion-transmitted Hepatitis B virus (HBV) infection. The safety improvements since then have been tremendous. From a level of a few infections per 1000 donations, the risk today, depending on the screening algorithm and additional measurements performed, has decreased to around 1:500,000 to 1:1,000,000, an improvement greater than 1000-fold compared to 50 years ago. This enormous gain in safety has been achieved through many factors, including development of increasingly more sensitive Hepatitis B antigen (HBsAg) assays; the adoption in some countries of hepatitis B core antibody (anti-HBc) screening; an improved donor selection procedure; HBV vaccination programs; and finally the introduction of HBV nucleic acid testing (NAT). Because there is a tendency in transfusion medicine to add one safety measure on top of another to approach the ultimate goal of zero risks, costs become increasingly a matter of debate. It is obvious that any new measure in addition to existing methods or measures will have very poor cost effectiveness. Therefore each country needs to perform its own calculation based on the country’s own epidemiology, resources, political and public awareness of the risks, in order to choose the correct and most cost-efficient measures. Ideally, each country would make decisions regarding implementation of additional blood safety measures in the context of both the perceived benefit and the allocation of overall health care resources.

An overview of occult hepatitis B virus infection

Occult hepatitis B virus (HBV) infection (OBI), alternatively defined as occult hepatitis B (OHB), is a challenging clinical entity. It is recognized by two main characteristics: absence of HBsAg, and low viral replication. The previous two decades have witnessed a remarkable progress in our understanding of OBI and its clinical implications. Appropriate diagnostic techniques must be adopted. Sensitive HBV DNA amplification assay is the gold standard assay for detection of OBI. Viral as well as host factors are implicated in the pathogenesis of OBI. However, published data reporting the infectivity of OBI by transfusion are limited. Several aspects including OBI transmission, infectivity and its relation to the development of chronic liver diseases and hepatocellular carcinoma have to be resolved. The aim of the present review is to highlight recent data on OBI with a focus on its virological diagnosis and clinical outcome.

Trends in prevalence of hepatitis B virus infection among Albanian blood donors, 1999-2009

BACKGROUND

Hepatitis B virus (HBV) was among the first virus known to be transmitted by blood and blood productions. The objective of this study is to determine the trend of hepatitis B virus in blood donors.

MATERIALS AND METHODS

In this study 79274 blood donors were retrospectively evaluated for HBsAg. The donors were selected using personal questionnaire, physical examination and testing blood before donation. Blood banks records are used as source of information. The blood donors samples were analyzed for the presence of hepatitis B surface antigen (HBsAg) by commercial available kits ELISA method, third generation (from Abbott laboratory, Germany). A sample was considered as HBsAg positive when found twice repeatedly reactive. Reactive samples were not confirmed with addition tests.

RESULTS

In the evaluation data, we found out that from 79274 of the total healthy blood donors, 15983 were voluntary donors, 52876 were family replacement donors and 10424 commercial blood donors. The prevalence of HBsAg in blood donors was 7.9%. It was increased steadily from 5.9% in 1999 to 9.1% in 2006 and decreased in 7.9% in 2009. According to blood donors status the HBsAg prevalence was 10.5% in commercial blood donors, 8.1% in voluntary donors and 8.6% in family replacement donors. The prevalence of anti-HBc in blood donors was 59.1%.

CONCLUSION

The prevalence of HBsAg was lower in voluntary non remunerate blood donors than commercial donors and family replacement blood donors. In FDs the prevalence was higher than VDs but lower than CDs. So, it is important to encourage the voluntary blood donors to become regularly blood donors.

Biospecimen repositories: are blood donors willing to participate?

BACKGROUND

Sponsored by the National Heart, Lung, and Blood Institute, the Retrovirus Epidemiology Donor Studies (REDS-I/-II) have conducted epidemiologic, laboratory, and survey research on volunteer blood donors. Some studies request additional permission to store biospecimens for future studies. The representativeness and applicability of studies performed using repositories may be reduced by low participation rates.

STUDY DESIGN AND METHODS

Demographics from subjects consenting to participate in the 2007 REDS-II Leukocyte Antibodies Prevalence Study (LAPS) repository were compared to "study-only" subjects. Data from the 1998 REDS-I survey of donor opinion regarding storage and use of biospecimens were also explored.

RESULTS

Overall, 91% of LAPS subjects agreed to participate in the repository. Odds of repository participation were lower among African American and Hispanic donors, 35- to 44-year-olds, donors who had not completed high school, and donors from one geographic location, regardless of other variables. Survey data from 1998 revealed that 97% of respondents approved of long-term storage of biospecimens, although only 87% indicated that they would personally participate. Many respondents would require notification or their permission be obtained before participation. Minority respondents would require permission or notification more often and were less certain they would personally participate in a repository.

CONCLUSION

Blood donors are quite willing to participate in biospecimen repositories. Regional differences and lower odds of participation in the minority blood donor population may result in a reduced number of biospecimens available for study and a decreased ability to definitely answer specific research questions in these populations.

Occult hepatitis B in blood donors in Indonesia: altered antigenicity of the hepatitis B virus surface protein

BACKGROUND AND AIMS

Occult hepatitis B virus infection (OBI) poses a challenge to the safety of blood donation. The prevalence of OBI is not well documented in Indonesia, although this information in such an endemic country is needed. This study was aimed to evaluate the prevalence of occult hepatitis B in blood donors from two cities of Indonesia, and to study the genetic variation and its effect on the predicted antigenicity of HBsAg.

METHODS

Serum samples of 309 regular blood donors negative for HBsAg were tested for anti-HBs and anti-HBc. Hepatitis B virus (HBV) DNA isolated from anti-HBc-positive samples were analyzed by polymerase chain reaction, cloned and sequenced. Antigenic properties of identified HBsAg mutants were predicted by calculation of the antigenic index.

RESULTS

Of the 309 HBsAg-negative samples, anti-HBc was positive in 134 (43.4%) and HBV DNA was detected in 25 (8.1%). Seven of the viremic samples had nucleotide substitutions (A521G, A551T, C582T, and A562G) in the S gene, causing amino acid mutations (T123A, M133L, and T143M) in the 'a' determinant of HBsAg that resulted in changes in the predicted antigenicity.

CONCLUSIONS

OBI was detected in blood donors' samples in Indonesia. Anti-HBc was shown to be a better screening parameter than HBsAg, however, it might result in the loss of donors particularly in endemic countries. HBsAg detection failure in this study might be due to mutations altering the protein antigenicity and/or the low-level carriage of HBV.

Transfusion-transmitted hepatitis B virus infection

Hepatitis B virus (HBV) remains a major risk of transfusion-transmitted infection due to the pre-seroconversion window period (WP), infection with immunovariant viruses, and with occult carriage of HBV infection (OBI). Reduction of HBV residual risk depends upon developing more sensitive HBV surface antigen (HBsAg) tests, adopting anti-HBc screening when appropriate, and implementing HBV nucleic acid testing (NAT), either in minipools or more efficiently in individual samples. HBV NAT combines the ability to significantly reduce the window period and to detect occult HBV carriage substantiating decades of clinical observation that HBsAg-negative/anti-HBc-positive blood could transmit HBV. Clinical observations suggest limited transmission rate of occult HBV compared to WP. Low transmission rate might be related to low viral load observed in OBIs or to the presence of mutants associated with occult carriage. OBIs carrying detectable anti-HBs ( approximately 50%) are essentially not infectious by transfusion. However, recent data suggest that the neutralizing capacity of low anti-HBs may be inefficient when overcome by exposure to high viral load. Anti-HBc blood units without detectable anti-HBs appear moderately infectious except in immunocompromised recipients. Immunodeficient elderly and patients receiving immunosuppressive treatments may be susceptible to infection with lower infectious dose even in the presence of anti-HBs. The immune status of blood recipients should be taken into consideration when investigating "post-transfusion" HBV infection. Pre-transfusion testing and post-transfusion long-term follow-up of recipients, and molecular analysis of the virus infecting both donor and recipient are critical to definitively incriminate transfusion in the transmission of HBV.

Lack of occult hepatitis B virus infection among blood donors with isolated hepatitis B core antibody living in an HBV low prevalence region of Iran

BACKGROUND

Occult hepatitis B virus (HBV) infection in blood donors is considered a potential threat for the safety of the blood supply, however conclusive studies on this issue are lacking. The aim of this study was to assess the occult HBV infection in blood donors with isolated hepatitis B core antibody (anti-HBc) living in the city of Arak, in the Central Province of Iran, as a low prevalence region for HBV.

METHODS

A total of 531 voluntary blood donors in Arak, Iran were included in this study. Hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs), anti-HBc, and hepatitis C antibody (anti-HCV) were tested in all subjects. The presence of HBV-DNA was determined quantitatively in plasma samples of cases with isolated anti-HBc (HBsAg-negative, anti-HBs-negative, and anti-HBc-positive) by real-time PCR using the artus HBV RG PCR kit on the Rotor-Gene 3000 real-time thermal cycler.

RESULTS

Of 531 subjects enrolled in this study, 11 (2.1%, 95% confidence interval 0.8-3.2%) had isolated anti-HBc. HBV-DNA was not detected in any of the cases with isolated anti-HBc.

CONCLUSIONS

Our study showed that all the blood donors with isolated anti-HBc were negative for HBV-DNA, and occult HBV infection did not occur in the blood donors of this low prevalence region for HBV infection.

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

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

CONCLUSION

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

Impact of occult hepatitis B virus infection and prior hepatitis B virus infection on development of hepatocellular carcinoma in patients with liver cirrhosis due to hepatitis C virus

OBJECTIVE

Although hepatitis B virus (HBV) DNA can be detected in liver or sera of patients without serum hepatitis B surface antigen (HBsAg), its clinical relevance in hepatocarcinogenesis remains controversial. This observational cohort study was conducted to clarify the risk factors, including the presence of serum HBV DNA and hepatitis B core antibody (anti-HBc), for hepatocellular carcinoma (HCC) in patients with hepatitis C virus (HCV)-related liver cirrhosis (LC).

MATERIAL AND METHODS

The study comprised 123 patients with LC due to HCV, and negative for HBsAg. The risk factors for HCC development were analyzed by univariate and multivariate analysis. Serum samples were assayed for HBV DNA using real-time polymerase chain reaction.

RESULTS

Serum HBV DNA was detectable in 14 patients (11.4%) and serum anti-HBc in 96 (78.0%). During the follow-up period (mean 53.3 months), 80 patients (65.0%) developed HCC. The cumulative HCC development rate was significantly higher in the anti-HBc-positive group than in the anti-HBc-negative group (p=0.0039), but did not differ between the serum HBV DNA-positive and -negative groups (p=0.8570). The multivariate analysis indicated that male gender, alpha-fetoprotein (AFP) 20 ng/ml or greater, average serum alanine aminotransferase (ALAT) 80 IU/l or greater and the presence of anti-HBc were independent risk factors for development of HCC (p=0.038, p=0.013, p=0.020 and p=0.001, respectively).

CONCLUSIONS

Serum anti-HBc, which indicates a previous HBV infection, has clinical significance in hepatocarcinogenesis in patients with HCV-related LC, but serum HBV DNA does not. Therefore, anti-HBc in serum is a significant predictor for HCC.

What can be revealed by extending the sensitivity of HBsAg detection to below the present limit?

BACKGROUND/AIMS

We investigated what can be revealed by extending the sensitivity of HBsAg detection to below the present limit.

METHODS

We examined the sensitivity of this immunoassay in comparison with real-time PCR detection of HBV DNA using serially diluted sera from HBV carriers. Low HBsAg was measured in 210 healthy volunteers and 368 patients with non-B chronic liver diseases who were negative for HBsAg by a standard EIA method.

RESULTS

The radical immunoassay was able to detect HBsAg at a concentration of 0.025 ng/ml. Low HBsAg was positive in 6 of 210 normal volunteers (2.86%), 5 of 65 non-B, non-C cirrhosis patients (7.69%), 6 of 62 non-B, non-C hepatocellular carcinoma patients (9.68%: p=0.04 vs. volunteers), 12 of 134 chronic hepatitis C patients (8.96%: p<0.02 vs. volunteers), and 11 of 107 hepatocellular carcinoma patients complicated by chronic hepatitis C (10.28%: p<0.008 vs. volunteers). Although no HBV DNA was positive in healthy volunteers, 9 patients with non-B chronic liver diseases were positive for HBV DNA by real-time PCR analysis.

CONCLUSIONS

Increasing the sensitivity of HBsAg detection to below the present limit has revealed that infection with HBV, including occult HBV, is far more endemic than suspected previously.

Anti-HBc screening in Egyptian blood donors reduces the risk of hepatitis B virus transmission

Occult hepatitis B virus (HBV) in blood donors is considered as a potential risk for transmission of HBV infection. The aim of this study was to determine the prevalence of anti-hepatitis B core antibody (anti-HBC) positivity in Egyptian blood donations as well as to estimate the frequency of HBV-DNA in anti-HBc-positive donations. The study included 760 Egyptian healthy blood donors, representing 26 different Egyptian governorates screened according to routine practice for the presence of hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies (Abs), HIV-1/2 Abs and Treponema Abs. The accepted blood units for donation were tested for the presence of total anti-HBc Abs by two tests. Positive units for anti-HBc were further tested for HBV-DNA by polymerase chain reaction. According to routine screening, a total of 48/760 units (6.3%) were rejected [38 (5%) HCV-Ab-positive units, 9 (1.18%) HbsAg-positive units and 1 (0.13%) Treponema-Ab-positive unit]. Among the accepted blood units for donation, prevalence of anti-HBc was 78/712 units (10.96%). HBV-DNA was detected in 9/78 (11.54%) of the anti-HBc-positive units, and thus, occult HBV infection was detected in 9/712 (1.26%) of the accepted blood donations. Implementing anti-HBc test to the routine assay for the forthcoming two decades would certainly eliminate possible HBV-infected units. Rejection of these units will be beneficial to decrease the risk of HBV transmission with its potential consequences particularly in immunocompromised recipients.

PRISM hepatitis B surface antigen detection of hepatits B virus minipool nucleic acid testing yield samples

BACKGROUND

Hepatitis B virus (HBV) residual risk has been estimated at 1:63,000-1:205,000 and introduction of more sensitive serological tests and nucleic acid testing (NAT) would reduce that risk. Sensitivity of the recently licensed Abbott PRISM hepatitis B surface antigen (HBsAg) CLIA and minipool (MP) HBV NAT has been described as comparable and thus the need for HBV NAT has not been compelling. In this study, eight samples identified as yield samples with MP HBV NAT were tested using the PRISM test.

STUDY DESIGN AND METHODS

Seven samples were identified using the Roche COBAS AmpliScreen HBV test and one additional sample was obtained from the clinical trial for the Roche cobas TaqScreen MPX test. Each of these samples was reactive by MP HBV NAT and nonreactive for HBsAg using one of three licensed enzyme immunoassay (EIA) tests. After licensure of the PRISM HBsAg, aliquots were tested with this assay, and DNA quantitation and genotyping were repeated where sample volume permitted.

RESULTS

Three samples (2000, 2300, and 61,000 copies/mL) produced reactive results with PRISM. Four samples with viral loads less than 300 copies per mL produced nonreactive results. One sample, originally quantitated at 37,000 copies per mL (but 3850 copies/mL in repeat testing) was also nonreactive by PRISM. Genotyping of this sample indicated a type C genotype with no mutations.

CONCLUSION

Adding serological sensitivity of PRISM CLIA reduced the NAT yield from the original 1: 385,555 to 1:610,488. However, MP HBV NAT still provides additional sensitivity over CLIA, even for a donation with a viral load of almost 4000 copies per mL.

Hepatitis B virus DNA-positive, hepatitis B surface antigen-negative blood donations intercepted by anti-hepatitis B core antigen testing: the Canadian Blood Services experience

BACKGROUND

The benefit of introducing anti-hepatitis B core antigen (HBc) screening for intercepting potentially infectious donations missed by hepatitis B surface antigen (HBsAg) screening in Canada was studied.

STUDY DESIGN AND METHODS

Anti-HBc testing of all donations was implemented in April 2005, along with antibody to hepatitis B surface antigen (anti-HBs) and hepatitis B virus (HBV) DNA supplemental testing of anti-HBc repeat-reactive, HBsAg-negative donations. The proportion of potentially infectious donations intercepted by anti-HBc over the initial 18 months of testing was calculated based on three assumptions relating infectivity of HBV DNA-positive units to anti-HBs levels. Lookback was conducted for all DNA-positive donations.

RESULTS

Of 493,344 donors, 5,585 (1.13%) were repeat-reactive for the presence of anti-HBc, with 29 (0.52%) being HBV DNA-positive and HBsAg-negative. The proportion of potentially infectious donations intercepted by anti-HBc screening was 1 in 17,800 if all HBV DNA-positive donations were infectious, 1 in 26,900 if infectivity was limited to donations with an anti-HBs level of not more than 100 mIU per mL, and 1 in 69,300 if only donations with undetectable anti-HBs were infectious. For 279 components in the lookback study, no traced recipients were HBsAg-positive and 7 recipients were anti-HBc-reactive in association with 4 donors, 3 of whom had an anti-HBs level of more than 100 mIU per mL and 1 of whom had a level of 61 mIU per mL.

CONCLUSION

Implementation of anti-HBc screening reduced the risk of transfusing potentially infectious units by at least as much as had been expected based on the literature. The lookback did not provide proof of transfusion transmission of HBV from HBV DNA-positive, anti-HBc-reactive, HBsAg-negative donors but it did not establish lack of transmission either.

Infectivity of blood components with low hepatitis B virus DNA levels identified in a lookback program

BACKGROUND

Japanese Red Cross (JRC) blood centers implemented anti-hepatitis B core antigen (HBc) screening in 1989 and 50-minipool (MP)-nucleic acid testing (NAT) in 2000. A systematic lookback study has been conducted to determine the hepatitis B virus (HBV) transmission risk of donations drawn in the pre-hepatitis B surface antigen (HBsAg) and/or MP-NAT window phase and by donors with occult HBV infection.

STUDY DESIGN AND METHODS

JRC blood centers have been storing aliquots of every blood donation since 1996. On the basis of the complete repository tube archives, all donations from repeat donors received from 1997 to 2004 were subjected to a lookback study. When repeat donors turned positive for HBV viral marker(s), repository tubes from their previous donations were tested for HBV with individual-donation (ID)-NAT. The frequency of ID-NAT-only-positive donations and the HBV transmission risk by the transfusion of those components were investigated.

RESULTS

HBV ID-NAT was performed on 15,721 repository tubes, and 158 tubes (1.01%) were found positive for the presence of HBV DNA. Of these 158 ID-NAT-only-positive donations, 95 (60%) were derived from carriers with low anti-HBc titers. Of 63 patients transfused with ID-NAT-only-positive components, 12 (19%) proved to be infected with HBV. Only 1 of 33 components with low anti-HBc titers could be identified as infectious, whereas 11 of 22 anti-HBc-negative components proved to be infectious. None of the 16 identified hepatitis B surface antibody-positive components showed serologic evidence of infection.

CONCLUSION

The clinically observed HBV infection risk caused by blood components from occult HBV carriers with low anti-HBc titers who slip through the JRC screening system is more than 10-fold lower than the transmission risk by donations in the pre-HBsAg and/or MP-NAT window phase.

Benefits of a blood donation archive repository: international survey of donor repository procedures and Scottish experiences

BACKGROUND

The use of a donation sample archive has been in place within the Scottish National Blood Transfusion Service for almost 35 years but the advent of human immunodeficiency virus donor testing led to this archive being kept for an indefinite period. This article describes the uses made of our archive repository.

STUDY DESIGN AND METHODS

Records of various potential transfusion transmission episodes were accessed and examined to assess the age of the archives investigated and the outcome of the investigations. Other uses of the archive repository were also investigated by reviewing the records of retrievals. The use of the archive to aid the interpretation of hepatitis C virus-indeterminate results was also conducted. Finally a global survey was performed to ascertain the temperature and length of storage used by various transfusion services.

RESULTS

A 3-year archive would have allowed for the investigation of 45 percent of cases (including all hepatitis B virus cases), while a 10-year archive would have allowed for 90 percent of cases. Only 34 percent of cases were shown to be transfusion-transmitted. Of 16 donors with c22-indeterminate bands on recombinant immunoblot assay, 2 (12%) could have been classified as confirmed-positive on the basis of their archive samples. A considerable proportion (41%) of the most recent requests for retrieval from the archive have been associated with the need to perform new mandatory tests for tissue donations at issue. Samples older than 3 years accounted for 25 percent of all samples retrieved. The global survey showed a variety of conditions in terms of both length and temperature of storage.

CONCLUSION

The use of a donation archive has been shown to be extremely useful in the investigation of potential transfusion-transmitted infections with most (66%) having no evidence of transfusion transmission. Although 90 percent of our cases could have been fully investigated with only a 10-year archive, perhaps the future retention period of hospital records should be considered when determining the length of storage of current donation archive samples.

Sensitivity of hepatitis B virus DNA transcription-mediated amplification testing in hepatitis B surface antigen-positive blood donations

BACKGROUND

The objective was to evaluate the performance of nucleic acid testing (NAT) in the detection of hepatitis B virus (HBV) infection in hepatitis B surface antigen (HBsAg)-positive blood donations.

STUDY DESIGN AND METHODS

A total of 253 HBsAg- and anti-hepatitis B core antigen (HBc)-positive samples (50 hepatitis B e antigen [HBeAg]-positive and 203 anti-HBe-positive) from blood donations collected in France were studied. The samples were investigated with a blood screening assay (Procleix Ultrio, Chiron/Gen-Probe) in minipool (MP; x8) and in individual-donation (ID) testing. All nonreactive samples were retested once, and nonreactive MP samples were assayed for viral load (VL).

RESULTS

All 50 HBeAg-positive samples were reactive in MP-NAT and ID-NAT. Of the 203 anti-HBe-positive donations, 80.3 percent were MP- and ID-reactive, 17.2 percent were MP-nonreactive and ID-reactive, and 2.5 percent were nonreactive in ID-NAT. Overall the sensitivity of ID-NAT was 98 percent versus 84 percent for MP-NAT. After retesting, 16 of the 35 MP-nonreactive and/or ID-reactive donations became MP-reactive and 2 of the ID-nonreactive donations became NAT-reactive. The capacity of Procleix Ultrio to detect HBV DNA was not related to HBsAg subtype, but correlated with the VL: the mean VL in the group of MP-nonreactive samples was 1,420 copies per mL vs. 17,000 copies per mL in the group of 40 MP-reactive samples.

CONCLUSION

These results demonstrate that HBV-NAT in ID format is far more effective in detecting viremia in chronic HBsAg carriers than in MP-NAT. The sensitivity of the NAT assay needs to be improved to be considered for replacing the current HBsAg assays, especially when anti-HBc testing is not performed.

Preliminary results of HBV DNA testing of Polish haemophilia patients--lack of occult HBV infection

Identification of hepatitis B virus (HBV) infection in the absence of surface antigen (HbsAg) became possible with the introduction of HBV DNA detection methods. Such occult HBV infection was diagnosed recently in about half of the Japanese HBsAg-negative haemophilia patients. The aim of our study was to assess the prevalence of occult HBV infection in Polish severe haemophilia population on the sample of 115 haemophilia A and B patients (mean age 34.9 +/- 10.9) treated with non-virus inactivated clotting factor preparations before 1995. HBV DNA was detected in nine HBsAg-positive patients (7.8%). The mean HBV DNA load was 72,800 IU mL(-1) (250-400,000 IU mL(-1)). Hepatitis C virus (HCV) RNA was found in six out of nine HBV-positive patients. In conclusion, HBV DNA was identified only in HBsAg-positive patients. Unlike in Japan, the frequency of occult HBV infection in Polish haemophilia population seems extremely rare or absent.

Hepatitis B virus blood screening: unfinished agendas

The risk of transfusion-transmitted hepatitis B virus (TTHBV) has been steadily reduced through the use of volunteer donors, enhanced donor questioning, and increasingly sensitive hepatitis B surface antigen (HBsAg) tests. In a few countries, screening by antibody to hepatitis B core antigen (anti-HBc) and/or hepatitis B virus (HBV) nucleic acid amplification tests (NAT) has also been introduced. Nevertheless, the risk of TTHBV in most countries is higher than the risk of either human immunodeficiency virus-1 (HIV-1) or hepatitis C virus (HCV). HBV screening practices vary both in terms of the markers screened and the tests employed, and are often dependent on a country's healthcare resources. Anti-HBc screening could be employed as an additional safety feature in HBV low-prevalence countries, but would lead to the rejection of a high percentage of otherwise acceptable donations in HBV moderate- and high-prevalence countries. It has been argued that only individual-donor HBV NAT testing would substantially reduce the risk of TTHBV beyond that achieved by the most sensitive HBsAg tests. However, studies from countries with low, moderate and high HBV prevalence have demonstrated NAT yield from window period- and late stage HBV-infected donors, even using minipool testing following the most sensitive HBsAg tests.

Epidemiology of HBV infection in Asian blood donors: Emphasis on occult HBV infection and the role of NAT

Hepatitis B virus (HBV) infection is endemic in many Asian countries. Among many transmission routes, transfusion is the one that should be prevented. The first major success in enhancing transfusion safety came with the implementation of hepatitis B surface antigen (HBsAg) in the early 1970s. However, the studies quoted in this review demonstrate that transmission by blood components negative for HBsAg can still occur in the acute phase of infection during the seronegative window period, or during chronic stages of infection (i.c. "occult" HBV infection, OHB). OHB is defined as the presence of HBV DNA in blood or liver tissues in patients negative for HBsAg, with or without any HBV antibodies. Because of limitations in current blood screening practices, OHB is an overlooked source of HBV transmission. For policy development on screening for HBV infection in blood donors, it would be useful to assess the relative contribution of the above two sources of transfusion-transmitted HBV infection from HBsAg-negative donations. New screening policy should be evaluated on the basis of available data or newly designed studies. While anti-HBc screening can climinate residual risk of occult HBV transmission by transfusion in low-endemic areas, it would not be practical in most parts of the world where the prevalence of anti-HBc is >10% as too many otherwise healthy donors will be ineligible. On the contrary, studies mentioned in this paper indicate that nucleic acid amplification test (NAT) or new HBsAg tests of enhanced sensitivity would be effective in the screening of blood donors for OHB in highly endemic countries. However, the cost-effectiveness of blood screening tests is a major concern in Asia. We therefore have systemically reviewed the literature on prevalence and infectivity of OHB in Asian countries and the possible role of NAT for identifying blood donors in the pre-HBsAg window phase or in later stages of OHB.

Transmission of occult hepatitis B virus by transfusion to adult and pediatric recipients in Taiwan

BACKGROUND/AIMS

The infectivity of occult hepatitis B virus (HBV), defined as HBsAg-negative but HBV DNA-positive, after transfusion has been low but not negligible. To address this, we investigated the incidence of post-transfusion HBV infection after receiving screened blood units in Taiwan.

METHODS

Consecutive HBV-naïve (anti-HBc-negative) recipients with normal ALT were followed for HBV DNA and serologic markers before and after transfusion. Among 4448 blood recipients, 467 (10.5%) were anti-HBc-negative. Post-transfusion 6-month follow-up was completed for 327. We identified 5 (1.5%) who developed hepatitis B viremia 1 week after transfusion. Three were children who later seroconverted to anti-HBc but with normal ALT indicating subclinical acute infection, despite all had anti-HBs from previous vaccination. One had transient transfusion-transmitted HBV without seroconversion to anti-HBc and one possibly had occult HBV infection. Our findings suggested the possibility that occult HBV infection was transmissible by transfusion. The incidence of post-transfusion acute HBV infection was 0.9% (100 per million units) in naïve recipients in Taiwan, a figure 7 approximately 40-fold higher than in developed countries. Moreover, some vaccinated children with anti-HBs were still susceptible.

CONCLUSIONS

Therefore, despite active immunization, sensitive screening assays for occult HBV infection such as nucleic acid amplification test could be considered in endemic areas.

Functional analysis of hepatitis B virus reactivating in hepatitis B surface antigen-negative individuals

The biological properties of latent or occult hepatitis B virus (HBV) have been poorly characterized as a result of the extremely low virus concentration. This report describes the phenotype of HBV reactivating in two patients after an HBsAg-negative latency period. One patient had latent HBV infection for at least 12 years without detectable viremia and symptoms of liver disease. Several full-length HBV genomes were cloned at reactivation, sequenced, and functionally tested by transfection into HuH7 cells. Genomes from both patients showed a low replication phenotype. It was caused at the level of RNA encapsidation or HBV DNA synthesis, but was not attributable to uncommon mutations in the terminal protein domain of P protein. A substantial subpopulation ( approximately 50%) of genomes from one patient did not express pre-S2/S mRNA and HBsAg. Site-directed mutagenesis identified a single G-A mutation within the S gene (position 458) to be responsible for this effect. The G458A mutation was also effective if the S gene was placed under control of a heterologous promoter. Furthermore, nuclear run-on transcription showed that the G458A mutation acts at the posttranscriptional level. The mutation affected a 5' splice site and prevented splicing of the pre-S2/S mRNA from position 458 to 1305. In conclusion, HBV latency may be characterized by viruses with reduced replication competence and antigen expression. In one patient, HBsAg expression was terminated by an as yet undescribed posttranscriptional mechanism. A single mutation inactivated a 5' splice site that is obviously essential for pre-S2/S mRNA accumulation. Supplementary material for this article can be found on the HEPATOLOGY website (http://www.interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

Infectious Risks Associated with the Transfusion of Blood Components and Pathogen Inactivation in Japan

Even after the implementation of the nucleic acid amplification testing (NAT) system, there remains a residual risk of viral transmission through blood transfusion because of the limited sensitivity of the reagents used and the pooling strategy of the current NAT system. From the calculation using NAT yield and the length of the window period, we presume that we will obtain 0.75 donations for human immunodeficiency virus and 0.58 donations for hepatitis C virus annually that are individual donation-NAT positive but 50-individual pool-NAT negative, figures that are comparable with those in other developed countries. The number of donations potentially positive for the hepatitis B virus genome is, however, considerably high in Japan and is estimated to be more than 100 annually, which is the sum of the donors in the minipool-NAT window period and the chronic carriers with a low viral load. The incidence of bacterial sepsis after transfusion is relatively low in Japan. This incidence is possibly attributable to the short shelf lives of platelet concentrate and red blood cell component, which are 3 and 21 days, respectively. In Japan, the implementation of a new technology to screen out or abrogate infectious agents in blood components is necessary while considering the balance between benefits and possible new risks or costs.

Transfusion-transmitted hepatitis E caused by apparently indigenous hepatitis E virus strain in Hokkaido, Japan

BACKGROUND

In industrialized countries, sporadic cases of hepatitis E have been reported in individuals who have never been in an endemic area. Hepatitis E virus (HEV) infection commonly occurs via the fecal-oral route but a potential risk of transfusion transmission route has been suggested.

STUDY DESIGN AND METHODS

A 67-year-old Japanese male patient who had never been abroad received a transfusion of blood from 23 voluntary donors and developed acute hepatitis with unknown etiology after transfusion. His blood samples were tested for viral markers of hepatitis viruses.

RESULTS

HAV, HBV, HCV, CMV, and EBV were ruled out as causative agents in this case. The patient's blood sample in the acute phase contained HEV RNA as well as IgM and IgG anti-HEV. HEV RNA was also detected in one of the FFP units transfused. The donor had no history of traveling abroad and had a normal ALT level at the time of donation. The PCR products from the patient and the donor showed complete identity for two distinct regions of HEV within open reading frame 1.

CONCLUSION

The patient was infected with HEV via transfused blood from a volunteer donor. A potential risk of posttransfusion hepatitis E should be considered even in nonendemic countries.

Should HBV DNA NAT replace HBsAg and/or anti-HBc screening of blood donors?

Prevention of transfusion-transmitted hepatitis B virus (HBV) has historically relied on serological screening of blood donors using progressively more sensitive HBsAg assays; in some countries anti-HBc assays have also been employed to detect chronic carriers with low-level viremia who lack detectable HBsAg. Nucleic acid amplification testing (NAT) for HCV and HIV has been successfully introduced to screen donors in many developed countries over the past several years; for logistical and cost reasons HCV/HIV NAT screening has been applied to mini-pools (MP) of eight to 96 donor specimens, with only minimal impact of MP dilutions on clinical sensitivity for interdiction of window period (WP) donations. In several countries (e.g., Japan and Germany), HBV NAT has been added to HIV/HCV MP-NAT blood donor screening with small incremental yields of HBsAg/anti-HBc-negative donations, and the major vendors of NAT systems (Roche and Chiron/Gen-Probe) have been developing triplex assays that include HBV DNA detection capacity without compromising HIV or HCV detection. Pooled specimen HBV NAT has also become the standard of practice for screening source plasma donors, with pressure to include HBV DNA detection as a required procedure for use of recovered plasma in manufacture of fractionated derivatives. However, there is controversy over the magnitude of the incremental yield and clinical benefit of HBV MP-NAT over serological screening strategies, as well as the impact of implementation of HBV NAT on need for retention of HBsAg and anti-HBc screening. This presentation will review recent modeled and empirical data on the value of HBV MP- and individual donation (ID)-NAT for detection of (1) pre-HBsAg WP units and (2) chronic anti-HBc-reactive carriers with undetectable HBsAg. The presentation will also review policy considerations and data that address the potential for discontinuation of either HBsAg or anti-HBc following implementation of HBV NAT. Finally it will address the cost effectiveness of incorporation of HBV DNA detection into HBV screening and NAT testing algorithms.

Prevalence of hepatitis B virus DNA in anti-HBc-positive/HBsAg-negative sera correlates with HCV but not HIV serostatus

BACKGROUND

Hepatitis B virus (HBV) DNA often remains detectable in serum despite clinical recovery and loss of HBsAg.

OBJECTIVE

To study whether coinfection with HIV and HCV influence the chance of detecting HBV DNA in sera with markers of past hepatitis B.

STUDY DESIGN AND RESULTS

The test panel included 160 anti-HBc-positive/HBsAg-negative sera collected in the diagnostic setting. The following parameters were determined in the sera: anti-HIV (32% positive), anti-HCV (34% positive), HCV RNA (18% positive), and anti-HBs (37% positive). A highly sensitive PCR (90%-detection limit 100 copies/ml) amplifying the terminal protein (TP) region of HBV was established and HBV DNA was detected in 12.5% of the samples. In 70% of these samples, the HBV DNA concentration was below 500 copies/ml as measured by real-time PCR in the S gene. Logistic regression analysis revealed that the chance of detecting HBV DNA was increased by a positive HCV serostatus (odds ratio 5.0, 95%-CI 1.6-15.7), whereas HIV coinfection (odds ratio 2.0, 95%-CI 0.7-5.8), anti-HBs (odds ratio 0.9, 95%-CI 0.3-2.6), and HCV RNA status (odds ratio 0.4, 95%-CI 0.1-1.7) had no statistically significant influence. In contrast, the chance of detecting HCV RNA in the subgroup of anti-HCV-positive sera was increased by HIV coinfection (odds ratio 4.5, 95%-CI 1.2-17.4). Sequencing of the TP PCR products revealed neither a specific phylogenetic origin of the circulating HBV DNA nor clustering of uncommon mutations in the TP region.

CONCLUSIONS

The prevalence of HBV DNA in serum of anti-HBc-positive/HBsAg-negative subjects correlates with HCV rather than HIV serostatus.

Frequency of HBV DNA detection in US blood donors testing positive for the presence of anti-HBc: implications for transfusion transmission and donor screening

BACKGROUND

An estimate of the rate of HBV DNA-positive, anti-HBc-positive units is important for evaluating the need for anti-HBc donor screening, especially in the context of HBV NAT.

STUDY DESIGN AND METHODS

HBsAg EIA-nonreactive, anti-HBc-reactive (Corzyme, Abbott Laboratories) specimens were retrieved from a repository and were retested for anti-HBc (with PRISM HBcore, Abbott Laboratories, currently under FDA review) and anti-HBs (with PRISM Ausab, Abbott Laboratories, research assay). HBV DNA testing using a PCR assay with a greater than 95 percent detection rate of less than 50 copies per mL was performed on a subset of specimens that were PRISM HBcore-reactive and were anti-HBs- negative or reactive at less than 100 IU per L.

RESULTS

A total of 395 of 1231 specimens eligible by our serologic criteria were tested by PCR. Four anti-HBs-negative specimens were PCR-positive with estimated HBV DNA copy numbers of 10 per 30 copies per mL in two specimens and 50 to 100 copies per mL in two others. The HBV DNA detection rate in anti-HBs-negative specimens was 3.7 percent, and the projected rate among all Corzyme-reactive specimens was 0.24 percent, leading to an estimated yield of 1 HBV DNA-positive, anti-HBc-positive unit in 49,000 units that were otherwise eligible for transfusion (95% CI, 1 in 16,600-1 in 152,600).

CONCLUSIONS

Anti-HBc screening detects HBsAg EIA-negative, HBV-infected donors at a rate comparable to the estimated residual risk for HBV window-period infections. The low viral load in the HBV DNA-positive samples suggests that minipool NAT will not detect most potentially infectious units from anti-HBc-positive donors.

Comparative sensitivity of HBV NATs and HBsAg assays for detection of acute HBV infection

BACKGROUND

A study was designed to estimate relative analytic sensitivity and window-period (WP) closure and to project incremental yield of newer HBsAg tests, pooled-sample NAT, and single-sample NAT, compared to currently licensed HBsAg tests.

STUDY DESIGN AND METHODS

HBV DNA and HBsAg test results for 23 HBV seroconversion (SC) panels were first analyzed to construct a model of primary HBV viremia. One-hundred representative samples were then selected from 10 panels and coded with 28 analytical controls. All 128 samples were tested by seven HBsAg tests and by four pooled-sample and three single-sample NAT assay formats. Results were analyzed to obtain differential times to HBV detection and combined with HBV incidence rates to project comparative yields.

RESULTS

HBV doubling time during the ramp-up phase was estimated at 2.56 days. HBsAg concentrations at cutoff for new tests ranged from 0.07 to 0.12 ng per mL, compared with 0.13 to 0.62 ng per mL for licensed tests. Estimated viral load at cutoff ranged from 102 to 267 IU per mL for new tests and from 363 to 1069 IU per mL for licensed tests. HBsAg tests detected 31 to 63 percent of early ramp-up phase samples in the 100-member seroconversion panel study, while pooled-sample NAT detected 55 to 71 percent and single-sample NAT, 82 to 99 percent. Compared with currently licensed HBsAg assays, newer HBsAg assays would reduce the WP by 2 to 9 days; pooled-sample NAT would reduce the WP by 9 to 11 days; and single-sample NAT would reduce the WP by 25 to 36 days.

CONCLUSION

Newer HBsAg tests would be expected to detect an additional 15 to 21 infected units per 107 donations, compared to licensed HBsAg tests. Sensitivity, WP closure, and yield projections for newer HBsAg assays and pooled-sample NAT are comparable. Single-sample NAT would increase yield by 13 to 15 units per 107 donations over pooled-sample NAT and newer HBsAg assays and by 35 to 50 units per 107 donations over currently licensed HBsAg assays.

Distribution of hepatitis B virus genotypes among American blood donors determined with a PreS2 epitope enzyme-linked immunosorbent assay kit

We genotyped 418 sera from volunteer blood donors from two large, regional blood centers in the United States who were HBsAg positive by an enzyme-linked immunosorbent assay (ELISA). The HBV genotypes were determined by a serological method using a preS2 epitope ELISA kit (Institute of Immunology, Tokyo, Japan) with monoclonal antibodies. Of the 418 samples, the genotypes of 320 could be determined (76.6%). One hundred forty-three (34.2%) were genotyped as A (preS2 subtype su), 31 (7.4%) were genotyped as B (subtype m), 59 (14.1%) were genotyped as C (subtype ks), 83 (19.9%) were genotyped as D or E (subtype ksu), and 4 (1.0%) were genotyped as F (subtype k). This kit cannot differentiate genotypes D and E. For 98 (23.4%) of the 418 samples, the genotype could not be determined; 11 of these 98 samples were positive for at least one of the preS2 genotype-specific epitopes (m, k, s, and u), but the combinations of positive epitopes were different from those of samples that could be genotyped; 45 had only the common epitope (b). In the group with a high signal-to-cutoff (S/C) ratio, the HBV genotype could be determined for 199 (84%) of 237 samples; in contrast, in the low-S/C-ratio group, only 10 (20%) of 51 samples could be genotyped (P < 0.001). These findings may indicate the limitation of genotyping samples with low S/C ratios for HBsAg by ELISA or the existence of genotype G or other new HBV genotypes in HBsAg-positive blood donors in the United States. Of the genotyped samples, 201 were assayed for HBeAg; only 9 (4.5%) were positive for HBeAg. The frequency of genotype C in HBeAg-positive donor samples (5 of 9 or 56%) was higher than that in HBeAg-negative donor samples (33 of 192, or 17%) (P = 0.022).

High-throughput HBV DNA and HCV RNA detection system using a nucleic acid purification robot and real-time detection PCR: its application to analysis of posttransfusion hepatitis

BACKGROUND

A high-throughput detection system was developed for HBV DNA and HCV RNA.

METHODS

A combination of real-time detection PCR using an automated system (PRISM 7700, PE Biosystems, Foster City, CA) and automatic viral nucleic acid extraction (BioRobot 9604, Qiagen, Hilden, Germany) was used as the high-throughput detection system. An internal control for HBV DNA detection was also developed.

RESULTS

Testing of 96 samples for HBV and HCV was completed within 5 hours. The sensitivity of this system almost equals that of the manual method using nested PCR. The addition of an internal control for HBV detection did not affect the sensitivity of the method and confirmed the accuracy of results. It was possible to quantify HBV in HBV+ samples that contain more than 500 genome equivalents per mL. We started using this system from June 1999 for testing stored donor and patient samples to analyze cases of posttransfusion hepatitis and identified three HBV+ donations that were implicated in posttransfusion hepatitis B.

CONCLUSION

The high-throughput detection system is a useful tool for HBV DNA and HCV RNA detection because it enables rapid and reliable testing of a large number of samples.