Transient occult hepatitis B virus infection in a blood donor with high viremia

Infectivity of Hepatitis B Virus Surface Antigen-Positive Plasma With Undetectable HBV-DNA: Can HBsAg Screening Be Discontinued in Egyptian Blood Donors?

Hepatitis B Virus (HBV) infectivity data were reviewed and the 50% infectious dose (ID50) was reassessed in different HBsAg-positive infection stages enabling modelling of transfusion-transmitted (TT)-HBV infection risk if HBsAg donor screening was replaced by individual donation nucleic acid amplification technology (ID-NAT). Quantitative HBsAg and HBV-DNA assays were performed against international standards to compare the ratio between potential infectious HBV virions and subviral HBsAg particles in Egyptian HBsAg-positive blood donors as well as in Japanese chimpanzee samples of known infectivity. HBV-DNA load below the quantification limit of detection was estimated against a reference standard by replicate NAT testing (n = 25). Infectivity of chimpanzee samples collected during ramp-up and declining viremic phase were tested in a human liver chimeric mice (HLCM) model and compared with published infectivity data from different HBsAg-positive infection stages. Lowest estimates of ID50 in HBsAg-positive plasma were 3-6 HBV virions in chimpanzee studies. Infectivity decreased approximately 10-100-fold in the declining viremic phase using HLCM. In acute phase samples, HBV to HBsAg particle ratios varied between 1:102-104 but in HBsAg-positive blood donors this particle ratio reached 1:106-1012 when viral load was below 100 HBV-DNA copies/mL. Modelled TT-HBV risk of an HBsAg-positive/ID-NAT nonreactive blood transfusion was estimated at 5.5%-27% for components containing 20-200 mL of plasma when assuming an ID50 of 316 (point estimate between 100 and 1000) virions. It cannot be ensured that discontinuation of HBsAg donor screening and reliance on ID-NAT alone is safe.

A Review of the Systemic Manifestations of Hepatitis B Virus Infection, Hepatitis D Virus, Hepatocellular Carcinoma, and Emerging Therapies

Chronic hepatitis B virus (HBV) infection affects about 262 million people worldwide, leading to over 820,000 deaths each year primarily due to cirrhosis and hepatocellular carcinoma. The World Health Organization has pledged to eliminate HBV as a health threat by 2030, but currently, no countries are on track to achieve this goal. One of the barriers to HBV elimination is stigma, causing shame, denial, self-isolation, self-rejection, and depression leading to those with chronic HBV less likely to get tested or seek treatment and more likely to conceal their infection. Other barriers include limited access to care and complicated and restrictive clinical practice guidelines. Increasing public and political efforts are necessary to raise awareness, increase access to care, and change screening and treatment guidelines. The current guidance of the American Association for the Study of Liver Diseases (AASLD) recommends testing only if patients are considered at risk, but this has proven to be ineffective. We propose a simplified "test all and treat all" approach with a 5-line guideline for HBV infection. Universal screening and treatment of adults is cost-effective and can prevent transmission by effectively managing chronic HBV. All patients who are hepatitis B surface antigen (HBsAg) positive with detectable HBV-DNA should receive treatment until HBsAg is undetectable for 12 months, as HBV-DNA transmission via blood transfusion can occur even at low viral loads of 16 copies/mL, and mother-to-child transmission is still a risk even with passive-active immunoprophylaxis. Furthermore, clinical outcomes after HBsAg clearance are significantly better than the clinical outcomes of those who remain HBsAg positive.

Infectivity of hepatitis B virus (HBV) surface antigen (HBsAg) positive plasma with undetectable HBV-DNA: Can HBsAg screening be discontinued in Egyptian blood donors?

HBV infectivity data were reviewed and the 50% infectious dose (ID50 ) was reassessed in different HBsAg positive infection stages enabling modelling of transfusion-transmitted (TT)-HBV infection risk if HBsAg donor screening was replaced by individual donation nucleic acid amplification technology (ID-NAT). Quantitative HBsAg and HBV-DNA assays were performed against international standards to compare the ratio between potential infectious HBV virions and subviral HBsAg particles in Egyptian HBsAg positive blood donors as well as in Japanese chimpanzee samples of known infectivity. HBV-DNA load below the quantification limit of detection was estimated against a reference standard by replicate NAT testing (n = 25). Infectivity of chimpanzee samples collected during ramp-up and declining viremic phase were tested in a human liver chimeric mice (HLCM) model and compared with published infectivity data from different HBsAg positive infection stages. Lowest estimates of ID50 in HBsAg positive plasma were 3-6 HBV virions in chimpanzee studies. Infectivity decreased approximately 10-100-fold in the declining viremic phase using HLCM. In acute-phase samples, HBV to HBsAg particle ratios varied between 1:102 -104 but in HBsAg positive blood donors this particle ratio reached 1:106 -1012 when viral load was below 100 HBV-DNA copies/ml. Modelled TT-HBV risk of an HBsAg positive/ID-NAT nonreactive blood transfusion was estimated at 9%-46% for components containing 20-200 ml of plasma assuming an ID50 of 316 (point estimate between 100 and 1000) virions. In the Egyptian setting, discontinuation of HBsAg donor screening and reliance on ID-NAT alone seems to be unsafe.

Molecular Detection of Occult Hepatitis B virus in plasma and urine of renal transplant patients in Khartoum state Sudan

OBJECTIVE

The aim of this study was to determine the OBI in plasma and urine samples from renal transplant patients using Multiplex Nested PCR.

METHOD

A total of 100 samples (plasma and urine) were collected from renal transplant patients admitted to the renal transplant center in Khartoum north, Sudan in 2019. For each sample, HBsAg, HBeAg and anti HBcAg were detected using Enzyme linked Immune sorbent assay (ELISA). The viral DNA was then extracted using viral DNA extraction kit and were then tested for HBV DNA by using multiplex nested PCR. Statistical analysis was done using statistical package of social science (IBM SPSS version 20.0) considering a P value ≤ 0.05 as a level of significance.

RESULTS

HBsAg were not detected in al patient but, HBeAg were 14 (14%) and anti HBcAg were 36 (36%)were detect by using ELISA. A total 18 (18%) and 3 out of 100 were found positive in plasma and urine samples, respectively. Regarding the virus genotypes, D, E and mixed D/E genotypes were detected in all positive samples. Females were significantly (P value=0.013) higher detectable with HBV than males in plasma samples CONCLUSION: OBI incidence in renal transplant patients is high in Sudan. The multiplex nested PCR had identified OBI with a high rate supporting the efficiency of using molecular techniques in detecting of HBV. This will lead to an appropriate diagnosis and minimizing the risk to be infected by HBV.

Pathological characterization of occult hepatitis B virus infection in hepatitis C virus-associated or non-alcoholic steatohepatitis-related hepatocellular carcinoma

Occult hepatitis B virus (HBV) infection, by definition, is a state in which infection with this virus does not manifest with the conventional diagnostic laboratory criteria reserved for the obvious form of HBV infection. As a result, occult HBV infection is commonly a surprise finding discovered accidently during the evaluation of other apparent liver diseases, such as hepatitis C virus (HCV) infection or non-alcoholic fatty liver disease and, more importantly, their evolution into life-threatening hepatocellular carcinoma. As infection with HCV and occult HBV is rarely considered when assessing these more obvious conditions, and in an attempt to offer a better understanding of this phenomenon, this study attempted to shed some light onto the uniqueness of occult HBV infection by addressing the natural history of HBV and HCV infections, as well as non-alcoholic fatty liver disease. This was carried out by taking into account the exclusive integration process undertaken by the HBV genome into infected host hepatocytes, with consideration given to conditions which afford reactivation of the occult infection and stress on the molecular mechanisms that underlie occult HBV infection. Finally, the clinical outcome of occult HBV infection and its relation to hepatocellular carcinoma is analyzed.

Direct comparison of three residual risk models for hepatitis B virus window period infections using updated input parameters

BACKGROUND AND OBJECTIVES

Comparison of two models for estimating residual transfusion transmission risk by NAT screened window period (WP) donations in South African repeat donors gave identical results for HIV but not for HBV. In order to understand discrepant HBV modelling outcomes, the values of input parameters in three HBV WP risk models were reviewed and subsequently applied to the same South African screening data generated by HBsAg PRISM and two NAT assays (Ultrio and Ultrio Plus). Two of the models were also compared using individual donation (ID)-NAT screening data from different geographical regions.

METHODS

Values of input parameters were derived from two published data sources and used in three risk models [(1) the incidence rate-WP risk day equivalent model, (2) the NAT yield WP ratio model and (3) the anti-HBc-negative HBsAg yield period ratio model] and subsequently applied to the same ID-NAT screening data.

RESULTS

The HBV WP transmission risk in South African repeat donations during a one-year Ultrio Plus NAT screening period was estimated as 22, 43 and 17 per million, respectively, for the three models, as compared to 56, 117 and 48 per million for HBsAg PRISM screening. The approximate two-fold higher estimate calculated with the NAT yield WP ratio model was corroborated in repeat donations from three of four regions in a multi-regional study. When another set of model input values (with shorter viraemia periods and a higher proportion of acute occult infections) was applied to the South African screening data, the relative difference in risk estimates between the three models became smaller.

CONCLUSIONS

Window period risk modelling for HBV is more complex than for HIV. Multiple factors affect the modelling outcomes. These include the values used for the length of transient HBsAg and HBV-DNA-positive phases, the proportion of acute occult and vaccine breakthrough infections and the assumption of random appearance of donors throughout the entire acute resolving infection phase. A substantial proportion of HBV WP NAT yields have very low viral load and lack donor follow-up data calling into question their definitive classification into the early acute (infectious) replication stage. Since these possible WP NAT yields most highly impact the NAT yield WP ratio model, we recommend relying on the more conservative estimates of the incidence rate-WP risk day equivalent model.

Reassessment of hepatitis B virus window periods for two transcription-mediated amplification assays using screening data of South African blood donors

BACKGROUND

Transcription-mediated amplification assays for HBV DNA detection have transitioned from the Ultrio to the Ultrio Plus assay, which features increased analytic sensitivity due to inclusion of a target enhancer reagent. The impact on HBV detection for different categories of HBV infection has not been fully evaluated.

STUDY DESIGN AND METHODS

Hepatitis B virus (HBV) DNA and hepatitis B surface antigen (HBsAg) detection rates as well as viral load (VL) distributions in HBV nucleic acid test (NAT)-yield samples were compared during 1 year of screening of South African blood donors with the Ultrio assay and the subsequent year by the Ultrio Plus version. HBV-DNA concentration at the HBsAg seroconversion point was established by regression analysis using a set of antibody to hepatitis B core antigen-negative acute viremic samples.

RESULTS

Ultrio Plus detected twofold more window-period (WP) NAT yield donations and 1.7-fold more occult HBV infections than Ultrio. The VL distribution data indicated that Ultrio not only missed samples of less than 100 copies/mL, but also a substantial number higher than this level. The VL at the HBsAg seroconversion point was estimated at 916 copies/mL, whereas the VL at the NAT-conversion points was calculated at 63 and 4.1 copies/mL for Ultrio and Ultrio Plus. This reduced the infectious WP (compared to HBsAg testing) by 10.3 and 20.4 days, respectively.

CONCLUSION

The higher-than-expected increase in HBV-NAT yields after introduction of the Ultrio Plus assay is likely attributable to variable sensitivity of the former Ultrio assay for different HBV samples. Therefore, previously published HBV WP reduction and residual risk estimates based on analytical sensitivity of the Ultrio assay need to be revised.

Occult hepatitis B virus and surface antigen mutant infection in healthy vaccinated cohorts and children with various forms of hepatitis and multiple transfusions

BACKGROUND AND AIMS

Despite the success of universal infant immunization initiated in Taiwan in 1984, occult hepatitis B virus infection (OBI) and circulating surface antigen mutants remain potential obstacles for eventual eradication of HBV infection.

METHODS

From 3299 apparently healthy, neonatally-vaccinated subjects (<30 years of age ) enrolled during 2014 serosurvey, we recruited all HBsAg-positive (n = 17), all HBsAg-negative but anti-HBc-positive (n = 132) and randomly selected HBsAg-negative and anti-HBc-negative subjects (n = 411). These recruited subjects and 81 HBsAg-negative children with various forms of hepatitis and multiple transfusions were analysed for serum HBV DNA.

RESULTS

In healthy, HBsAg-negative subjects, OBI frequency was higher in anti-HBc-positive than anti-HBc-negative individuals (8/90[8.9%] vs 8/301[2.7%], P = 0.0192) aged <18-years, but was not different between anti-HBc-positive and anti-HBc-negative individuals (0/11[0%] vs 3/110[2.7%], P > 0.05) aged 18 to 30 years. OBI occurred more frequently in children of HBsAg-positive mothers than in children of HBsAg-negative mothers (10/101 [9.9%] vs 1/75 [1.3%], P = 0.025). The prevalence of surface 'a' determinant (aa110-160) mutants was 13.3% (2/15) in OBI subjects compared to 36.4% (4/11) in HBsAg-positive subjects (P > 0.05). OBI was found in 30% (3/10) of serologic 'non-A to E' viral hepatitis, 14.3% (3/21) of chronic hepatitis C and 2.0% (1/50) of multitransfused, thalassemic children.

CONCLUSIONS

In this highly immunized population, surface antigen mutant infection is uncommon and has low contribution to OBI development. HBsAg screening plus highly sensitive HBV DNA assays are needed for assurance of blood supply safety. Multiple transfusions from HBsAg-negative blood donors rarely result in persistent HBV infection. HBV might be related to some of serologic 'non-A to E' viral hepatitis.

Hepatitis B virus infection among sexually active individuals in Nigeria: a cross-sectional study

Introduction

Hepatitis B virus (HBV) infection is a major health challenge in sub-Saharan African countries. Chronic HBV infection is a risk factor for severe disease progression. Perinatal and sexual transmissions of Hepatitis B virus are the main routes of infection in HBV endemic countries like Nigeria. However, there is paucity of data as regards the major contributory route of transmission to chronic HBV infection in this region. Also, in Nigeria, not everyone at high risk of the infection has been identified. Therefore our study investigated the prevalence of HBV infection among sexually active individuals in Nigeria.

Methods

Blood samples collected from 463 participants (360 sexually active individuals and 103 teenagers) recruited from health institutions across the country were tested for the presence of HBsAg, and HBV nucleic acid related antigen (HBVNRAg) by ELISA. Positive samples were further tested for the presence of HBeAg and antiHBe by ELISA. Data were analyzed using Chi-square and binary logistic regression at p = 0.05.

Results

HBsAg and HBVNRAg were detected in 10.4% and 7.6% of the participants respectively. STI clinic attendees had the highest prevalence for HBsAg (17%; p = 0.002). Teenagers had the lowest HBsAg (1.9; p = 0.002) and HBVNRAg (2.9%; p = 0.0001) prevalence rates. Male gender (p = 0.01) and reproductive age group (p=0.009) were the major predictors of chronic HBV infection.

Conclusion

Sexual transmission was identified as the major contributor to chronic HBV infection. Sexually active individuals especially those with STIs are high risk groups for chronic HBV infection. Interventions targeted at this group is therefore recommended.

Occult Hepatitis B Virus Infection and Associated Genotypes among HBsAg-negative Subjects in Burkina Faso

Background

The presence of HBV DNA in the liver (with detectable or undetectable HBV DNA in the serum) of individuals tested HBsAg negative by currently available assays is defined occult B Infection (OBI). It remains a potential transmission threat and risk to HBV chronic infection. The purpose of this study was to determine the OBI prevalence among HBsAg negative subjects and to characterize associated genotypes.

Methods

Blood samples of 219 HBsAg-negative subjects tested by ELISA were collected. HBV DNA was investigated in all samples. Viral loads were determined using quantitative real-time PCR. All samples were screened for HBV markers (anti-HBc, anti-HBe, HBsAg). The Pre-S/S region of the HBV genome was sequenced. The database was analyzed using the SPSS and Epi info software. Phylogenetic analysis was performed using the BioEdit and MEGA software.

Results

Of the 219 samples, 20.1% were anti-HBc positive, 1.8% HBeAg and 22.8% were anti-HBe positive. Fifty-six (56) (25.6%) of the samples had a detectable HBV DNA and viral loads ranging from 4 IU/mL to 13.6 10⁶ IU/mL. Sixteen of them (16/56) had a viral load < 200 IU/mL, resulting in an OBI prevalence of 7.3% (16/219) in our study. The remaining 40 subjects had viral loads > 200 IU/mL, resulting in a “false OBI” prevalence of 18.3% (40/219). HBV genotype E was predominant followed by the quasi-sub-genotype A3. A single “false OBI” strain had the characteristic mutation G145R. Other mutations were observed and all located in the major hydrophilic region (MHR) of the S gene.

Conclusion

The study reported a prevalence of 7.3% of occult hepatitis B infection. It confirms the predominance of genotype E and the existence of a subgroup of quasi-sub-genotype A3 of HBV in Burkina Faso. It further provides information on the presence of “false OBI.” This study has found mutations in the major hydrophilic region (MHR) of the pre-S/S gene of HBV.

Occult Hepatitis B virus infection in previously screened, blood donors in Ile-Ife, Nigeria: implications for blood transfusion and stem cell transplantation

BACKGROUND

Hepatitis B virus (HBV) transmission through blood transfusion is reduced by screening for hepatitis B surface antigen (HBsAg). However this method cannot detect the presence of occult hepatitis B virus infection. This study sought to determine the prevalence of occult hepatitis B virus infection among blood donors in Ile-Ife, Nigeria. For the first time in Nigeria we employed an automated real-time PCR- method to investigate the prevalence of occult HBV in blood donors.

METHODS

Blood donors screened with HBsAg immunochromatographic rapid test kits at the blood transfusion units of two hospitals and found to be negative were recruited into the study. Questionnaires to elicit risk factors for HBV infection were administered and then 10 ml of blood was collected from each donor. Plasma samples obtained from these HBsAg negative blood donors were screened again for HBsAg using an enzyme-linked immunosorbent assay (ELISA) method, and those found negative were screened for the presence of total antibody to the HBV core antigen (anti-HBc) using ELISA method. Those positive to anti-HBc were then tested for HBV DNA, using an automated real-time PCR method.

RESULTS

Five hundred and seven blood donors found HBsAg negative by immunochromatographic rapid test kits at both blood transfusion units, were tested for HBsAg using ELISA and 5 (1 %) were HBsAg positive. The 502 found negative were tested for anti-HBc and 354 (70.5 %) were found positive implying previous exposure to HBV and 19 (5.4 %) of the 354 anti-HBc positive had HBV DNA signifying occult HBV infection. No risk factors were found to be associated with the presence of HBV DNA among those who tested positive.

CONCLUSION

Occult HBV infection exists in blood donors in Ile-Ife, Nigeria and the use of HBsAg alone for screening prospective donors will not eliminate the risk of HBV transmission in blood transfusion or stem cell transplantation.

Molecular Characterization of Pre-Core/Core and S Region of Hepatitis B Virus in Hemodialysis Patients With Occult Hepatitis B Infection

BACKGROUND

Occult hepatitis B infection (OBI) is a major public health problem worldwide, which harbors potential risk of hepatitis B virus (HBV) transmission through blood transfusion and transplantation. OBI is characterized by the presence of HBV-DNA in the blood or liver tissue without detectable hepatitis B surface antigen (HBsAg) in the serum. An important cause of OBI is the occurrence of mutations in the HBV genome, especially in the S region.

OBJECTIVES

The study aims to analyze mutations in S and pre-core/core regions of HBV-DNA in hemodialysis patients.

PATIENTS AND METHODS

Sera of 216 hemodialysis patients were tested for HBsAg and hepatitis B core antibody (HBcAb) by ELISA. Sera of patients that tested negative for HBsAg were evaluated by PCR for the detection of HBV-DNA in the S and pre-core/core regions. In total, six PCR products were sequenced, aligned, and compared with the HBV reference sequence. Amino acid deletion and nucleotide substitution were considered mutations in S and pre-core/core regions of HBV-DNA.

RESULTS

Among 216 patients, 203 (93.98%) and 175 (81.01%) sera samples tested negative for HBsAg and HBcAb, respectively. Among all HBsAg-negative samples, six (2.9%) tested positive for HBV-DNA, including four (1.97%) for S and two (0.98%) for pre-core regions. All four (1.97%) samples that tested positive for the S region belonged to HBV-subtype awy. The amino acid sequence of all four samples showed the YMDD motif in position 204 (rtM204). There were three amino acid substitutions in the S region (T127P, P153L, and F170S) and one substitution in the RT region (Y135S). Moreover, two (0.98%) pre-core/core positive patients had an unexpected stop codon in position 1896.

CONCLUSIONS

This study indicates that 2.9% of hemodialysis patients had OBI, which is considered as a major public health problem worldwide. Moreover, we observed three mutations in S region, including T127P, P153L, and F170S, which caused OBI. This study is first to report a mutation analysis of HBV in hemodialysis patients in southwestern Iran. These results indicate that current screening tests based on HBsAg detection are not reliable for detection of HBV infection in dialysis patients.

High prevalence of occult hepatitis B infection in an African urban population

Occult hepatitis B infection (OBI), the presence of low hepatitis B virus (HBV) deoxyribonucleic acid (DNA) levels in patients without detectable hepatitis B surface antigen (HBsAg), has significant implications for understanding the natural history of hepatitis B infection. We determined the prevalence of OBI in African patients using a sensitive polymerase chain reaction (PCR) assay and describe here the characteristics of OBI in an urban African hospital population. Routine serological testing as well as molecular studies were performed on sera from 314 patients who were part of a previous study from an urban hospital emergency room in Kampala, Uganda, detecting HBV DNA using a nested PCR with amplification of two regions of the HBV genome. HBV viral loads (VL) were determined by real-time PCR (rtPCR) and sequencing performed to determine HBV genotype and S gene mutations. Among 314 subjects tested, 50 (16%) had chronic HBV infection, 94 (30%) had detectable HBV DNA despite testing HBsAg negative (OBI), and 170 (54%) were not infected. VLs of OBI subjects were relatively low although 19 (20%) had VL exceeding 10(4)  IU ml(-) . Subjects with chronic HBV infection had a higher median VL compared to OBI patients (P < 0.001). All chronic HBV sequenced (10) and 83/89 OBI sequences were genotype A, the remaining six being genotype D. S-gene mutations were present in some but not all OBI patients (48%). OBI is more prevalent among African patients than previously thought. This may have implications for clinical management and transfusion-related HBV transmission.

Mutations associated with occult hepatitis B in HIV-positive South Africans

Occult hepatitis B is characterized by the absence of hepatitis B surface antigen (HBsAg) but the presence of HBV DNA. Because diagnosis of hepatitis B virus (HBV) typically includes HBsAg detection, occult HBV remains largely undiagnosed. Occult HBV is associated with increased risk of hepatocellular carcinoma, reactivation to chronic HBV during immune suppression, and transmission during blood transfusion and liver transplant. The mechanisms leading to occult HBV infection are unclear, although viral mutations are likely a significant factor. In this study, sera from 394 HIV-positive South Africans were tested for HBV DNA and HBsAg. For patients with detectable HBV DNA, the overlapping surface and polymerase open reading frames (ORFs) were sequenced. Occult-associated mutations-those mutations found exclusively in individuals with occult HBV infection but not in individuals with chronic HBV infection from the same cohort or GenBank references-were identified. Ninety patients (22.8%) had detectable HBV DNA. Of these, 37 had detectable HBsAg, while 53 lacked detectable surface antigen. The surface and polymerase ORFs were cloned successfully for 19 patients with chronic HBV and 30 patients with occult HBV. In total, 235 occult-associated mutations were identified. Ten occult-associated mutations were identified in more than one patient. Additionally, 15 amino acid positions had two distinct occult-associated mutations at the same residue. Occult-associated mutations were common and present in all regions of the surface and polymerase ORFs. Further study is underway to determine the effects of these mutations on viral replication and surface antigen expression in vitro.

Selected phenotypic assays used to evaluate antiviral resistance and viral fitness of hepatitis B virus and its variants

Currently available antiviral therapies specifically target viral replication by blocking reverse transcription with orally given nucleos(t)ide analogues and are able to specifically suppress viral replication. The unique replication strategy of hepatitis B virus (HBV), however, allows long-term persistence of the viral genome within infected hepatocytes in spite of successful therapy. Thus, antiviral therapy needs to be continued for years. Therapy can result either in the emergence and selection of antiviral-resistant variants or the relapse of viral replication after the termination of antiviral therapy. Resistance is a major problem for 4 of the 5 approved HBV nucleos(t)ide analogues, but it is not the only reason for therapy failure. An accurate phenotypic in vitro assay for resistance allows the identification of a viral variant selected in vivo during antiviral therapy and helps to find therapeutic alternatives. Furthermore, these assays can be used to measure viral fitness and pathogenicity in vitro. With the help of these assays, the prediction of emerging viral variants with drug resistance or increased pathogenic potential can be realized. Phenotypic resistance tests for HBV are not trivial because the virus cannot be readily grown in cell culture. This review focuses on currently available phenotypic assays to evaluate antiviral resistance of HBV and fitness of viral variants in general.

Prevalence of occult HBV among hemodialysis patients in two districts in the northern part of the West Bank, Palestine

Occult hepatitis B infection is the case with undetectable HBsAg, but positive for HBV DNA in liver tissue and/or serum. Occult hepatitis B infection among hemodialysis patients in Palestine has been understudied. In this study, 148 hemodialysis patients from 2 northern districts in Palestine, Jenin (89) and Tulkarem (59), were investigated for occult hepatitis B, HBV, HCV infections with related risk factors. ELISA and PCR were used for the detection of anti-HBc and viral DNA, respectively. The overall prevalence of occult hepatitis B infection among the study group was 12.5% (16/128). Occult hepatitis B infection is more prevalent among males with most cases (15/16) from Jenin District. About one-third (42/132) of the hemodialysis patients were anti-HBc positive. Approximately 27% of the hemodialysis patients were infected with HCV. Around 20% (28/140) were positive for HBV DNA, but only 8.2% (12/146) of the hemodialysis patients were positive for HBsAg. The comparison between hemodialysis patients with occult hepatitis B infection and those without occult hepatitis B infection for selected risk factors and parameters as liver Enzyme, age, sex, HCV infection, blood transfusion, kidney transplant, anti-HBc, and vaccination showed no statistical significance between both categories. Duration of hemodialysis significantly affected the rate of HCV infection. HCV is significantly higher in hemodialysis patients with both Diabetes mellitus and hypertension. The prevalence of occult hepatitis B infection among hemodialysis patients is high; requiring stringent control policies. HBsAg assay is insufficient test for accurate diagnosis of HBV infection among hemodialysis patients.

Detection and identification of occult HBV in blood donors in Taiwan using a commercial, multiplex, multi-dye nucleic acid amplification technology screening test

BACKGROUND

The ability of a new generation commercial, multiplex, multi-dye test from Roche, the cobas TaqScreen MPX test, version 2.0, to detect and identify occult HBV infections was evaluated using routine donor samples from Kaohsiung Blood Bank, Taiwan.

STUDY DESIGN AND METHODS

A total of 5973 samples were tested by nucleic acid amplification technology (NAT); 5898 in pools of six, 66 in pools of less than six and nine samples individually. NAT-reactive samples were retested with alternative NAT tests, and follow-up samples from the donors were tested individually by NAT and for all the HBV serological markers.

RESULTS

Eight NAT-only-reactive donors were identified, and follow-up samples were obtained from six of the donors. The results indicated that all eight donors had an occult HBV infection with viral loads <12 IU/ml.

CONCLUSION

The cobas(®) TaqScreen MPX test, version 2.0, has an advantage over the current Roche blood screening test, the cobas TaqScreen MPX test, for screening donations in countries with a high prevalence of occult HBV infections since the uncertainty associated with identifying samples with very low viremia is removed by the ability of the test to identify the viral target in samples that are reactive with the cobas TaqScreen MPX test, version 2.0.

Enhanced detection of hepatitis B virus in Hong Kong blood donors after introduction of a more sensitive transcription-mediated amplification assay

BACKGROUND

A total of 517,072 and 399,326 consecutive donations were screened for hepatitis B virus (HBV) by individual-donation nucleic acid testing (ID-NAT) using Ultrio and Ultrio Plus assays (Novartis Diagnostics), respectively. The impact of more sensitive HBV detection by the latter assay version was established by comparing NAT yield and transmission risk.

STUDY DESIGN AND METHODS

Donations were screened simultaneously for HBV serologic markers and ID-NAT, followed by discriminatory assay and confirmatory test algorithms. Window period (WP) reduction and residual HBV transmission risk were computed using mathematical modeling.

RESULTS

HBV NAT-yield rates for both WP and occult HBV infection (OBI) increased significantly from 1:34,471 to 1:17,362 (p = 0.036) and from 1:5120 to 1:2450 (p < 0.0001), despite a 1.2- and 1.6-fold decrease in hepatitis B surface antigen (HBsAg) incidence and prevalence rates respectively. After adjusting for this bias, the WP and OBI NAT-yield improvement factors were 2.3 and 3.4, respectively, higher than a less than 1.5-fold increase estimated from analytical sensitivity studies on HBV Genotype A and C standards. The current WP transmission risk with Ultrio Plus screening was estimated at 1:55,000 compared to 1:22,000 with HBsAg testing.

CONCLUSION

The observed greater than twofold enhanced WP NAT yield with the Ultrio Plus assay can be explained by greater than 10-fold increased analytical sensitivity in detecting the HBV Genotype B and C strains in Hong Kong. Direct comparison studies of the two assay versions on dilutions of HBV NAT-yield samples are required to confirm this hypothesis.

Epidemiology of HBV S-gene mutants in the Liguria Region, Italy: Implications for surveillance and detection of new escape variants

HBV surface antigen (HBsAg) variants may impair diagnosis or allow the virus to escape vaccine-induced immunity and their circulation in the population can represent a Public Health threat. Their prevalence, however, is not yet completely established. Evidence indicates that amino acid substitutions within HBsAg can lead to conformational changes which allow mutated HBV to escape the vaccine-induced antibodies used in the screening tests. In such scenario, the aim of this study was to investigate the prevalence of HBV S-Gene escape mutants by sequencing the gene in a cohort of Ligurian patients monitored for viral load, genotype and drug resistance and to evaluate the risk of false negative HBsAg detection by routine screening tests. From 2007 to 2011, in 256 consecutive samples from Ligurian HBV positive patients sequencing assay for detection of RT/S-Gene mutations using Trugene HBV Genotyping kit (Siemens Healthcare Diagnostics Inc., Tarrytown, NY) was performed. Serological HBV tests and viral load were also performed. Analyzed sequences revealed G145R mutation in 8/256 (3.1%) examined sequences, it was alone in 5 patients and accompanied by other HBsAg mutations in 3 samples. HBsAg resulted undetectable by 3 of the 8 samples, derived from patients with multiple mutations: T126I-T131A-C139Y-E/D144G, T126I-M133L, and P120Q-T126I. The emergence of these mutants, at least the G145R, has already been addressed as a public health concern because of its capability of escaping the immune system. In the present study we point out a second aspect connected with their existence and with similar potential negative impact on public health, that is their capability of escape punctual detection.

Occult hepatitis B virus infection among Egyptian blood donors

AIM

To identify blood donors with occult hepatitis B virus (HBV) infection (OBI) to promote safe blood donation.

METHODS

Descriptive cross sectional study was conducted on 3167 blood donors negative for hepatitis B surface antigen (HBsAg), hepatitis C antibody (HCV Ab) and human immunodeficiency virus Ab. They were subjected to the detection of alanine aminotransferase (ALT) and aspartate transaminase (AST) and screening for anti-HBV core antibodies (total) by two different techniques; [Monoliza antibodies to hepatitis B core (Anti-HBc) Plus-Bio-Rad] and (ARC-HBc total-ABBOT). Positive samples were subjected to quantitative detection of antibodies to hepatitis B surface (anti-HBs) (ETI-AB-AUK-3, Dia Sorin-Italy). Serum anti-HBs titers > 10 IU/L was considered positive. Quantitative HBV DNA by real time polymerase chain reaction (PCR) (QIAGEN-Germany) with 3.8 IU/mL detection limit was estimated for blood units with negative serum anti-HBs and also for 32 whose anti-HBs serum titers were > 1000 IU/L. Also, 265 recipients were included, 34 of whom were followed up for 3-6 mo. Recipients were investigated for ALT and AST, HBV serological markers: HBsAg (ETI-MAK-4, Dia Sorin-Italy), anti-HBc, quantitative detection of anti-HBs and HBV-DNA.

RESULTS

525/3167 (16.6%) of blood units were positive for total anti-HBc, 64% of those were anti-HBs positive. Confirmation by ARCHITECT anti-HBc assay were carried out for 498/525 anti-HBc positive samples, where 451 (90.6%) confirmed positive. Reactivity for anti-HBc was considered confirmed only if two positive results were obtained for each sample, giving an overall prevalence of 451/3167 (14.2%) for total anti-HBc. HBV DNA was quantified by real time PCR in 52/303 (17.2%) of anti-HBc positive blood donors (viral load range: 5 to 3.5 x 10(5) IU/mL) with a median of 200 IU/mL (mean: 1.8 x 10(4) ± 5.1 x 10(4) IU/mL). Anti-HBc was the only marker in 68.6% of donors. Univariate and multivariate logistic analysis for identifying risk factors associated with anti-HBc and HBV-DNA positivity among blood donors showed that age above thirty and marriage were the most significant risk factors for prediction of anti-HBc positivity with AOR 1.8 (1.4-2.4) and 1.4 (1.0-1.9) respectively. Other risk factors as gender, history of blood transfusion, diabetes mellitus, frequent injections, tattooing, previous surgery, hospitalization, Bilharziasis or positive family history of HBV or HCV infections were not found to be associated with positive anti-HBc antibodies. Among anti-HBc positive blood donors, age below thirty was the most significant risk factor for prediction of HBV-DNA positivity with AOR 3.8 (1.8-7.9). According to HBV-DNA concentration, positive samples were divided in two groups; group one with HBV-DNA ≥ 200 IU/mL (n = 27) and group two with HBV-DNA < 200 IU/mL (n = 26). No significant difference was detected between both groups as regards mean age, gender, liver enzymes or HBV markers. Serological profiles of all followed up blood recipients showed that, all were negative for the studied HBV markers. Also, HBV DNA was not detected among studied recipients, none developed post-transfusion hepatitis (PTH) and the clinical outcome was good.

CONCLUSION

OBI is prevalent among blood donors. Nucleic acid amplification/HBV anti core screening should be considered for high risk recipients to eliminate risk of unsafe blood donation.

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

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

CONCLUSION

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

Hepatitis B virus infection among first-time blood donors in Italy: prevalence and correlates between serological patterns and occult infection

BACKGROUND

A prospective, 1-year study was performed among Italian first-time, volunteer blood donors, who account for 12% of all donations, in order to assess the frequency and serological patterns of hepatitis B virus infection and the presence of occult infection.

MATERIALS AND METHODS

Consecutive donors (n=31,190) from 21 blood transfusion centres, from age classes not subjected to universal HBV vaccination, were tested for HBsAg and anti-HBc by commercial immunoassays. Other HBV serological markers were searched for and qualitative and quantitative assessments of HBV-DNA were made in HBsAg and/or anti-HBc-positive individuals.

RESULTS

Of the 31,190 donors studied, 100 (0.32%) were positive for both HBsAg and anti-HBc, 2 for HBsAg (0.01%) alone, and 2,593 (8.3%) for anti-HBc. Of these last, 86.7% were also positive for anti-HBs (with or without anti-HBe), 2.9% were positive for anti-HBe without anti-HBs and 10.4% had no other HBV markers (anti-HBc alone). A general north-south increasing gradient of HBV prevalence was observed. Circulating HBV-DNA was found in 96.8% of HBsAg-positive subjects as compared to 0.55% (12/2,186) of anti-HBc-positive/HBsAg-negative subjects, with higher frequencies among anti-HBs-negative than among anti-HBs-positive ones (1.68% vs. 0.37%; p <0.01) and among the 57 cases positive for both anti-HBc and anti-HBe (7%). HBV-DNA levels were significantly higher in HBsAg-positive subjects than in HBsAg-negative ones (median: 456 IU/mL vs. 38 IU/mL).

CONCLUSIONS

The prevalence of HBV infection among Italian first-time blood donors is much lower than in the past. The presence of occult infections in this group was confirmed (frequency: 1 in 2,599), supporting the hypothesis of long-term persistence of HBV infection after clearance of HBsAg. HBsAg and nucleic acid amplification testing for blood screening and vaccination against HBV are crucial in order to further reduce the risk of transfusion-transmitted HBV towards zero.

Molecular mechanisms underlying occult hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.

Molecular mechanisms underlying occult hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.

Reactivation of hepatitis B virus with mutated hepatitis B surface antigen in a liver transplant recipient receiving a graft from an antibody to hepatitis B surface antigen- and antibody to hepatitis B core antigen-positive donor

BACKGROUND

Fresh-frozen plasma (FFP) may contain antibodies to hepatitis B surface antigen (HBsAg, anti-HBs). These anti-HBs may lead to a misinterpretation of the actual hepatitis B immune status. Furthermore, they may not only confer protection against hepatitis B virus (HBV), but may also favor the selection of HBsAg mutants.

CASE REPORT

We report a case of de novo HBV infection in a HBV-naïve recipient with alcoholic liver disease, who received a liver from a donor with antibodies to hepatitis B core antigen (HBcAg, anti-HBc) and anti-HBs.

RESULTS

A lookback investigation revealed the following: 1) Due to anti-HBs passively acquired through FFP, the recipient was considered immune to HBV and did not receive anti-HBV prophylaxis. 2) Within 1 year after transplantation he developed hepatitis B in absence of any elevated liver enzymes after the anti-HBs by FFP declined. 3) Despite an infection with HBV-containing wild-type HBcAg, the patient did not seroconvert to anti-HBc positivity. 4) The replicating HBV encoded two HBsAg mutations, first sQ129R and 4 months later sP127S. They map to the highly conserved “α” determinant of the HBsAg loop.

CONCLUSION

1) Passive transfer of anti-HBs from FFP led to an erroneous pretransplant diagnosis of HBV immunity when the patient was in fact HBV-naïve. 2) HBsAg mutations might have been selected in escape from donor's actively produced anti-HBs and the recipient's anti-HBs by FFP might have favored this selection. 3) It is doubtful whether hepatitis B immunoglobulin could have prevented the reactivation. 4) Antiviral prophylaxis would have been crucial.

Molecular characterization of hepatitis B virus strains circulating in Belgian patients co-infected with HIV and HBV: overt and occult infection

Hepatitis B virus (HBV) and human immunodeficiency virus (HIV) have similar transmission routes, implying that patients infected with HIV are at particular risk for HBV infection. Patients who are co-infected with HIV and HBV progress more rapidly to end-stage liver disease and different HBV genotypes may have a distinct impact on disease progression. One hundred ninety-one anti-HBc-positive sera from Belgian patients co-infected with HIV and HBV were collected during 1998-2008. Full-length HBV genomes as well as large S or partial S genes were amplified and their molecular evolutionary history was analyzed. Clinically, 30 (65.8%) patients were categorized as "overt infection" and 16 (34.7%) cases were categorized as "occult infection." Five distinct HBV genotypes comprising A (69.6%), E (19.6%), followed by D, C, and G were detected. HBV genotype A was observed in all clinical groups and in patients with varying ethnical background. HBV genotype E could be detected in African patients who were mostly infected by heterosexual contacts. Several clinically important mutations at the HBs major hydrophilic region were detected in the new isolates but with no significant difference between occult and overt infection. The high prevalence of HBV genotype A in overt and occult cases, and in particular the detection of certain HBV subgenotypes in patients co-infected with HIV and HBV that carry diagnostic escape mutations, may provide useful information for national guidelines for prophylaxis and treatment.

Challenges in hepatitis B detection among blood donors

PURPOSE OF REVIEW

The availability of hepatitis B virus (HBV) nucleic acid testing (NAT) for donor blood screening led to its implementation in low prevalence and high prevalence countries. Genomic detection was a substantial addition to HBV surface protein (HBsAg) screening by detecting window period infections and 'occult' HBV infections (OBIs), characterized by undetectable HBsAg, low viral load and presence of serological markers (anti-HBc and/or anti-HBs). OBIs are the result of multiple, poorly understood mechanisms including incomplete immune control mutations of the HBsAg antigenic determinants; abnormal expression of S gene; and inhibition of genome transcription. Infectivity for the recipient is high for window period blood and relatively low for OBIs.

RECENT FINDINGS

The number of cases identified by NAT ranges between 1 : 1000 and 1 : 50 000, depending on epidemiology and assay sensitivity whether NAT is implemented in individual donations or pools of samples. OBI donors are generally older than 45 years except in Africa, carry very low viral load (median 11-25  IU/ml) and have normal alanine transaminase levels. Cases carrying anti-HBc alone are more infectious than those with low level of anti-HBs. Evidence of HBsAg escape mutants that are undetected by commercial assays has been published. Inhibition of HBsAg mRNA production and export are potential mechanisms of OBI occurrence.

SUMMARY

HBV blood safety is improved by NAT for HBV DNA when applied to individual donations. Until the sensitivity of NAT is improved, both this method and HBsAg screening are needed to eliminate potentially infectious blood donations. Occult HBV characterization clarifies new facets of HBV natural history.

HBsAg-negative mono-infection with hepatitis B virus genotype G

Infection with a genotype G strain of hepatitis B virus (HBV-G) often occurs as a co-infection with HBV genotype A. In mono-infection with HBV-G, the production of hepatitis B surface antigen (HBsAg), HBe antigen and anti-HBe seems diminished, hampering the serological diagnosis of HBV-G mono-infection. To corroborate this notion, we studied in detail a series of samples of a blood donor with transient HBV-G infection. In this donor, during the temporary presence of HBV DNA and the seroconversion to HBcore antibodies (anti-HBc), no HBsAg or hepatitis B e antigen was detected. During follow-up, no anti-HBe appeared. Multiple resistance mutations to lamivudine were present, demonstrating primary infection with a resistant HBV strain. Cloning and sequencing indicated that no other HBV genotype but genotype G was present. Like other HBV-G isolates, the DNA sequence of the HBsAg a-determinant showed no mutations that could explain the failure to detect HBsAg. Our findings demonstrate that HBV genotype G mono-infection occurs and that routine serology is unsuitable for its detection.

High levels of serum hepatitis B virus DNA in patients with 'anti-HBc alone': role of HBsAg mutants

It remains unclear how the detection of hepatitis B core antibody (anti-HBc) in the absence of hepatitis B surface antigen (HBsAg) and antibody (anti-HBs) should be interpreted and whether all patients with this pattern need to be tested for hepatitis B virus (HBV)-DNA. This study aimed at reassessing the significance of 'anti-HBc alone' in unselected sera referred to the clinical laboratory and determining whether significant HBV viraemia can be found in this setting. Of the 6431 patients tested for HBsAg, total anti-HBc and anti-HBs in a Paris hospital over a 1-year period, 362 (5.6%) had 'anti-HBc alone' (24.8% of anti-HBc-positive patients). Only 11 of the 362 sera (3.0%) were found to be false positive. One patient was in the resolving phase of acute hepatitis B. HBV-DNA was detected in 10 of 362 (2.8%) patients, using a commercial standardized assay (threshold: 350 IU/mL). Viral loads exceeded 10(4) copies/mL in 6 of 10 patients. Mutations in the HBsAg immunodominant region were identified in seven of the viraemic patients. HBsAg was detected in only two cases when retested by one of the latest, multivalent assays. Neither human immunodeficiency virus nor hepatitis C virus serostatus distinguished between patients with and without HBV-DNA. In conclusion, 'anti-HBc alone' should be considered a risk marker for a so-called 'false occult' HBV infection with significant viraemia. Indeed, results in this hospital population indicate that a small proportion of patients with 'anti-HBc alone' have high viral loads, revealing the occurrence of infection with HBV mutants that escape detection even by multivalent HBsAg assays.

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.

Significance of detecting anti-HBc among Egyptian male blood donors negative for HBsAg

BACKGROUND

Screening for hepatitis B virus surface antigen (HBsAg) reduces the risk of transfusion-transmitted hepatitis B viral (HBV) infection. However, the absence of HBsAg in the blood of apparently healthy individuals may not be sufficient to ensure the lack of circulating HBV. Blood containing anti-hepatitis B core antibody (anti-HBc) without detectable presence of HBsAg might be infectious; therefore, screening for anti-HBc has been implemented in some countries resulting in a decrease in the risk of post-transfusion HBV infection.

AIM

To study the seroprevalence of anti-HBc. The relationship between anti-HBc positivity and the presence of circulating HBV among healthy blood donors negative for HBsAg will be helpful to decide whether supplemental testing may bring additional safety to blood products.

MATERIAL AND METHODS

A total of 1026 serum samples collected from HBsAg-negative Egyptian healthy male donors were tested for the presence of anti-HBc (both IgM and IgG types) using the competitive enzyme-linked immunosorbent assay technique. Anti-HBc-positive samples were subjected to real-time polymerase chain reaction to confirm the presence of HBV DNA.

RESULTS

Of the 1026 samples tested, 80 (7·8%) blood samples were found to be reactive to anti-HBc. Of those, HBV DNA was detected in five of the samples (6·25%). The levels of detected viraemia were variable among the five donors.

CONCLUSION

This study shows the insufficient effectiveness of HBsAg screening in protecting blood recipients from HBV infection. Inclusion of anti-HBc testing should be considered in the screening of blood donors.

Nucleic acid testing to detect HBV infection in blood donors

BACKGROUND

The detection of hepatitis B virus (HBV) in blood donors is achieved by screening for hepatitis B surface antigen (HBsAg) and for antibodies against hepatitis B core antigen (anti-HBc). However, donors who are positive for HBV DNA are currently not identified during the window period before seroconversion. The current use of nucleic acid testing for detection of the human immunodeficiency virus (HIV) and hepatitis C virus (HCV) RNA and HBV DNA in a single triplex assay may provide additional safety.

METHODS

We performed nucleic acid testing on 3.7 million blood donations and further evaluated those that were HBV DNA-positive but negative for HBsAg and anti-HBc. We determined the serologic, biochemical, and molecular features of samples that were found to contain only HBV DNA and performed similar analyses of follow-up samples and samples from sexual partners of infected donors. Seronegative HIV and HCV-positive donors were also studied.

RESULTS

We identified 9 donors who were positive for HBV DNA (1 in 410,540 donations), including 6 samples from donors who had received the HBV vaccine, in whom subclinical infection had developed and resolved. Of the HBV DNA-positive donors, 4 probably acquired HBV infection from a chronically infected sexual partner. Clinically significant liver injury developed in 2 unvaccinated donors. In 5 of the 6 vaccinated donors, a non-A genotype was identified as the dominant strain, whereas subgenotype A2 (represented in the HBV vaccine) was the dominant strain in unvaccinated donors. Of 75 reactive nucleic acid test results identified in seronegative blood donations, 26 (9 HBV, 15 HCV, and 2 HIV) were confirmed as positive.

CONCLUSIONS

Triplex nucleic acid testing detected potentially infectious HBV, along with HIV and HCV, during the window period before seroconversion. HBV vaccination appeared to be protective, with a breakthrough subclinical infection occurring with non-A2 HBV subgenotypes and causing clinically inconsequential outcomes. (Funded by the American Red Cross and others.).

Occult hepatitis B virus infection in Thai blood donors

BACKGROUND

An evaluation by the National Blood Center, the Thai Red Cross Society, of two commercial multiplex nucleic acid tests (NATs; the Chiron PROCLEIX ULTRIO test and the Roche Cobas TaqScreen MPX test) for screening Thai blood donors for hepatitis B virus (HBV), hepatitis C virus, and human immunodeficiency virus Type 1 identified 175 HBV NAT-reactive/hepatitis B surface antigen (HBsAg)-negative donors. The classification of the HBV infection of these donors was confirmed by follow-up testing.

STUDY DESIGN AND METHODS

Index samples were tested for HBV serologic markers and HBV viral loads were determined. Donors were followed for up to 13 months and samples were tested with both NAT assays and for all HBV serological markers.

RESULTS

Of 175 HBV NAT-yield donors, 72 (41%) were followed. Based on the follow-up results, the majority of donors who were followed had an occult HBV infection (66.7%), followed by donors with a primary, acute infection (26.4%). The majority of donors in this latter group (20.8%) were in the window period. Three donors (4.2%), who were anti-HBs positive, had a reinfection or breakthrough infection.

CONCLUSION

The majority of donors detected during routine screening, who were HBsAg negative and NAT reactive, had an occult HBV infection, thus validating the decision to introduce NAT for blood donations in Thailand.

Efficacy of hepatitis B virus (HBV) DNA screening and characterization of acute and occult HBV infections among blood donors from Madrid, Spain

BACKGROUND

Screening of blood units for hepatitis B virus (HBV) DNA identifies donations collected during the window period (WP) of the acute infection and may improve viral safety of the blood supply. It also leads to the detection of occult hepatitis B infection (OBI).

STUDY DESIGN AND METHODS

From January 2005 to December 2006, a total of 383,267 blood units were screened for hepatitis B surface antigen (HBsAg) and HBV DNA in two transfusion centers in Madrid, using either individual-donation nucleic acid testing (ID-NAT) or minipool (MP-NAT) of eight donations (MP8). Samples positive for HBV DNA and negative for HBsAg were confirmed by a second molecular test, the viral DNA was quantified, and a genome fragment including the region encoding the major hydrophilic region (MHR) of HBsAg was sequenced.

RESULTS

The overall yield of HBV DNA-positive, HBsAg-negative units was 1 in 21,282 (18 cases), higher when using ID-NAT than MP8-NAT (1:9862 vs. 1:51,011; p < 0.01). Four donations (1/95,817) were collected during the infectious pre-HBsAg WP, one during an early recovery stage, and the remaining 13 (1/29,482) were OBIs, six of whom had no detectable antibody to HBsAg. Low-level Genotype D HBV DNA was detected in all OBI cases; the frequencies of this genotype and MHR amino acid substitutions were significantly higher than reported from unselected Spanish HBsAg carriers. Donors with OBI had normal aminotransferase levels and were significantly older than donors carrying HBsAg.

CONCLUSIONS

Blood donors in the WP and with OBI are not uncommon in Madrid and are detected at a higher frequency with ID-NAT than MP-NAT.