Hepatitis E: the current state of play

The hepatitis E virus (HEV) is a major cause of acute hepatitis globally. Genotypes 1 and 2 (G1 and G2) are obligate human pathogens transmitted faeco-orally, leading to epidemics in developing countries. In contrast, genotypes 3 and 4 (G3 and G4) have a wider host range, including humans, but are primarily porcine viruses and are transmitted from animals to humans as a food-borne zoonosis when meat from an infected animal is consumed. HEV is increasingly recognised as a problem in developed countries, including countries in Europe. G3 HEV is now the most common cause of acute viral hepatitis in the UK and cases continue to rise. The majority of these infections are acquired within the UK and thought to be from insufficiently cooked meat, predominantly processed pork meat. Previously thought to only cause self-limiting disease, HEV infection can persist in immunosuppressed patients, which may lead to chronic hepatitis and the rapid development of cirrhosis. Of particular interest to the transfusion community has been the possibility of transfusion-transmitted HEV, which has been reported from countries classically considered HEV-endemic but also non-endemic countries in Europe and Japan. This has prompted some countries to introduce screening for HEV in blood donations.

Acute hepatitis B virus infection with delayed appearance of hepatitis B core antibody in an immunocompromised patient: a case report

Background

Despite the introduction of universal hepatitis B immunization programs worldwide, outbreaks of acute infection still occur in unimmunized individuals. A timely diagnosis of hepatitis B is necessary to ensure adequate clinical care and public health interventions that will reduce transmission. Yet, interpretation of hepatitis B serological markers can be complex. We present a case of hepatitis B with atypical markers, including delayed appearance of hepatitis B core antibody.

Case presentation

A 62-year-old white woman was identified as a sexual contact of a male individual with acute hepatitis B virus infection. She had a history of recurrent low-grade non-Hodgkin lymphoma and had recently received immunosuppressive therapy. At baseline she had a negative serology and received three double doses (40 μg) of Engerix-B vaccine (hepatitis B vaccine) with a 0-month, 1-month, and 6-month schedule. One month following the last dose, hepatitis B surface antigen was positive in the absence of hepatitis B core antibody. The only sign of infection was a slight elevation of alanine aminotransferase enzymes a few months after first sexual contacts with the male individual. Hepatitis B virus infection was later confirmed despite the absence of hepatitis B core antibody. The development of hepatitis B core antibody was finally noted more than 6 months after the first positive hepatitis B surface antigen and more than 12 months after elevation of alanine aminotransferase enzymes. Immunosuppression including rituximab treatment was the most likely explanation for this serological profile. On her last medical assessment, she had not developed HBeAg seroconversion despite lower hepatitis B virus deoxyribonucleic acid levels with tenofovir treatment.

Conclusions

When confronted with positive hepatitis B surface antigen in the absence of hepatitis B core antibody, consideration should be given to the possibility of both acute and persistent infection particularly in the setting of immunosuppression so that appropriate clinical management and public health interventions can take place. Given the increasing use of biologicals such as anti-tumor necrosis factor therapies either alone or with other immunosuppressive agents, this phenomenon may be encountered more frequently.

Acute hepatitis E mimicking a flare of disease in a patient with chronic autoimmune hepatitis

 Acute hepatitis E is becoming increasingly recognised in Europe with up to 40% of the population in Southern France being exposed to the virus, which is harboured in pigs. Patients with known liver disease may present with acute hepatitis E and present a diagnostic challenge. For example patients with autoimmune hepatitis (AIH) who are immunosuppressed and contract hepatitis E may be at increased risk of developing chronicity due to concurrent immunosuppression. Importantly, the diagnosis may be missed with the infection misdiagnosed as an autoimmune flare, and immunosuppression increased by the attending physician, thus enhancing the risk of chronicity of infection leading to progressive liver injury in immunocompromised patients. We report a case of acute hepatitis E in a patient with AIH and discuss the features that helped us differentiating it from an autoimmune flare.

Cytomegalovirus viral load testing of blood using quantitative polymerase chain reaction in acutely unwell HIV-1-positive patients lacks diagnostic utility

We examined the usefulness of measuring cytomegalovirus (CMV) viral load (VL) in blood using quantitative polymerase chain reaction (qPCR) in establishing a diagnosis of CMV end-organ disease in consecutive unwell HIV-infected patients. The indication for testing for CMV, CD4 count, CMV VL and presence of CMV end-organ disease were abstracted from case-notes. During a 42-month period, 216 tests were performed in 181 patients; the majority (61%) had CD4 counts <100 cells/ μL. The prevalence of detectable CMV by qPCR was 43.5% (94/216) with a prevalence of CMV end-organ disease of 7.4% (16/216). Of patients with CMV detectable by qPCR, 72 % (50/69) had CD4 counts <100 cells/ μL. For patients with definite CMV end-organ disease, the positive predictive value of detectable CMV by qPCR was 10% (9/94), and the negative predictive value was 98% (119/122). In acutely unwell HIV-infected patients, detection of CMV by qPCR is a poor predictor of CMV end-organ disease.

Prevalence of Hepatitis E Virus Infection in Pigs at the Time of Slaughter, United Kingdom, 2013

Pigs raised in the United Kingdom are unlikely to be the source of UK human infections.

Since 2010, reports of infection with hepatitis E virus (HEV) have increased in England and Wales. Despite mounting evidence regarding the zoonotic potential of porcine HEV, there are limited data on its prevalence in pigs in the United Kingdom. We investigated antibody prevalence, active infection, and virus variation in serum and cecal content samples from 629 pigs at slaughter. Prevalence of antibodies to HEV was 92.8% (584/629), and HEV RNA was detected in 15% of cecal contents (93/629), 3% of plasma samples (22/629), and 2% of both (14/629). However, although HEV is prevalent in pigs in the United Kingdom and viremic pigs are entering the food chain, most (22/23) viral sequences clustered separately from the dominant type seen in humans. Thus, pigs raised in the United Kingdom are unlikely to be the main source of human HEV infections in the United Kingdom. Further research is needed to identify the source of these infections.

Virology, serology, and demography of hepatitis E viremic blood donors in South East England

BACKGROUND

Hepatitis E virus (HEV) Genotype 3 (G3) in England comprises two principal phylogenetic groups (Group 1 and Group 2) and can be transmitted by transfusion. Unselected screening identified 79 viremic donors; 76 participated in a follow-up study.

STUDY DESIGN AND METHODS

Viral RNA dynamics, phylogenetics, and seroconversion were characterized in the donors. Detailed demographic, travel, clinical, and lifestyle questionnaires were undertaken.

RESULTS

The majority of viremic individuals (57/79) were seronegative at time of donation but all seroconverted. Viremia was short-lived, with a median of 6.5 weeks to confirmed viral clearance. All infections were acquired in the United Kingdom and were G3, with Group 2 viruses predominating (43/54; 80%). Infection was associated with some clinical symptoms both at and after donation (8/77; 10%). Viral loads and symptoms were more pronounced in Group 1 infections. There was no serologic evidence of reinfection. Donors were more commonly male (p = 0.002); both male and female donors were older than comparator donors. Animal contact was unlikely to be the source of infection. Consumption of chicken and pig meat was common to all infected donors; processed pig meat was most commonly purchased from one particular retail chain.

CONCLUSION

Viremic donors represent primary infection in older members of the community and reflect a widespread zoonotic in the United Kingdom. The two phylogenetic groups of HEV G3 display different pathogenicity and the more common Group 2 appears less adapted to humans. There are no objective demographic criteria that can identify donors at enhanced HEV risk.

Detection of Vaccine-Induced Antibodies to Ebola Virus in Oral Fluid

Blood sampling to assess production of antigen-specific antibodies after immunization is commonly performed, but it presents logistical difficulties for trials carried out during an infectious disease outbreak. In this study, we show that antibodies may be reliably detected in oral fluid collected in a minimally invasive manner without use of sharps. Clinical Trials Registration. NCT02240875.

Variability and pathogenicity of hepatitis E virus genotype 3 variants

Infection with hepatitis E virus (HEV) can be clinically inapparent or produce symptoms and signs of hepatitis of varying severity and occasional fatality. This variability in clinical outcomes may reflect differences in host susceptibility or the presence of virally encoded determinants of pathogenicity. Analysis of complete genome sequences supports the division of HEV genotype 3 (HEV-3) variants into three major clades: 3ra comprising HEV isolates from rabbits, and 3efg and 3abchij comprising the corresponding named subtypes derived from humans and pigs. Using this framework, we investigated associations between viral genetic variability of HEV-3 in symptomatic and asymptomatic infections by comparing HEV-3 subgenomic sequences previously obtained from blood donors with those from patients presenting with hepatitis in the UK (54 blood donors, 148 hepatitis patients), the Netherlands (38 blood donors, 119 hepatitis patients), France (24 blood donors, 55 hepatitis patients) and Germany (14 blood donors, 36 hepatitis patients). In none of these countries was evidence found for a significant association between virus variants and patient group (P>0.05 Fisher's exact test). Furthermore, within a group of 123 patients in Scotland with clinically apparent HEV infections, we found no evidence for an association between variants of HEV-3 and disease severity or alanine aminotransferase level. The lack of detectable virally encoded determinants of disease outcomes in HEV-3 infection implies a more important role for host factors in its clinical phenotype.

No evidence of transfusion transmission of Adenovirus and Epstein-Barr virus infections in paediatric recipients post-bone marrow transplant

Adenovirus and Epstein-Barr virus can cause significant morbidity and mortality in paediatric patients post-bone marrow transplant. The source of infection is thought to be either reactivation of latent viruses or primary infection. We have investigated whether transfusion of blood components from viraemic donors could provide a route of primary infection in these patients and sought the prevalence of viraemia in the blood donor population from England. In 32 linked donor/recipient samples and 300 unselected blood donors, we found no evidence to suggest that these infections in paediatric bone marrow transplant recipients had been acquired from transfused blood components.

Molecular epidemiology of newly acquired hepatitis C infections in England 2008-2011: genotype, phylogeny and mutation analysis

BACKGROUND

Analysis of laboratory testing data collected through the Sentinel Surveillance programme has provided a method for identifying individuals who have recently acquired their hepatitis C virus (HCV) infection. Access to samples from these individuals provided a rare opportunity to undertake molecular characterization studies.

OBJECTIVES

To describe the epidemiology and genetic diversity of hepatitis C in recent seroconverter infections and to predict how this will impact on HCV treatment and control.

STUDY DESIGN

One hundred and forty seven samples were available from individuals, identified to have recently acquired their HCV infection. Genotype determination with additional phylogenetic analysis was carried out on NS5B sequences. Analysis across the NS3 region investigated the presence of antiviral resistance mutations. Where possible, molecular data was linked to demographic and risk/behavioural factor information.

RESULTS

The majority of new infections occurred in males with a mean age of 37 years. The most commonly observed genotypes were 1a (49%) and 3a (42%) and injecting drug use (58%) was the most common risk factor. Genotype distribution differed between persons who inject drugs and those with other risk factors suggesting two possible epidemics. Phylogenetic analysis indicated possible transmission networks within specific risk groups. Amino acid changes associated with antiviral resistance were noted in the NS3 region in some samples.

CONCLUSIONS

Continued surveillance of linked molecular, virological, demographic and epidemiological information on recently acquired infections will contribute to understanding the on-going HCV epidemic in England.

Molecular epidemiology of newly acquired hepatitis C infections in England 2008-2011: genotype, phylogeny and mutation analysis

BACKGROUND

Analysis of laboratory testing data collected through the Sentinel Surveillance programme has provided a method for identifying individuals who have recently acquired their hepatitis C virus (HCV) infection. Access to samples from these individuals provided a rare opportunity to undertake molecular characterization studies.

OBJECTIVES

To describe the epidemiology and genetic diversity of hepatitis C in recent seroconverter infections and to predict how this will impact on HCV treatment and control.

STUDY DESIGN

One hundred and forty seven samples were available from individuals, identified to have recently acquired their HCV infection. Genotype determination with additional phylogenetic analysis was carried out on NS5B sequences. Analysis across the NS3 region investigated the presence of antiviral resistance mutations. Where possible, molecular data was linked to demographic and risk/behavioural factor information.

RESULTS

The majority of new infections occurred in males with a mean age of 37 years. The most commonly observed genotypes were 1a (49%) and 3a (42%) and injecting drug use (58%) was the most common risk factor. Genotype distribution differed between persons who inject drugs and those with other risk factors suggesting two possible epidemics. Phylogenetic analysis indicated possible transmission networks within specific risk groups. Amino acid changes associated with antiviral resistance were noted in the NS3 region in some samples.

CONCLUSIONS

Continued surveillance of linked molecular, virological, demographic and epidemiological information on recently acquired infections will contribute to understanding the on-going HCV epidemic in England.

Hepatitis E virus in blood components: a prevalence and transmission study in southeast England

BACKGROUND

The prevalence of hepatitis E virus (HEV) genotype 3 infections in the English population (including blood donors) is unknown, but is probably widespread, and the virus has been detected in pooled plasma products. HEV-infected donors have been retrospectively identified through investigation of reported cases of possible transfusion-transmitted hepatitis E. The frequency of HEV transmission by transfusion and its outcome remains unknown. We report the prevalence of HEV RNA in blood donations, the transmission of the virus through a range of blood components, and describe the resulting morbidity in the recipients.

METHODS

From Oct 8, 2012, to Sept 30, 2013, 225,000 blood donations that were collected in southeast England were screened retrospectively for HEV RNA. Donations containing HEV were characterised by use of serology and genomic phylogeny. Recipients, who received any blood components from these donations, were identified and the outcome of exposure was ascertained.

FINDINGS

79 donors were viraemic with genotype 3 HEV, giving an RNA prevalence of one in 2848. Most viraemic donors were seronegative at the time of donation. The 79 donations had been used to prepare 129 blood components, 62 of which had been transfused before identification of the infected donation. Follow-up of 43 recipients showed 18 (42%) had evidence of infection. Absence of detectable antibody and high viral load in the donation rendered infection more likely. Recipient immunosuppression delayed or prevented seroconversion and extended the duration of viraemia. Three recipients cleared longstanding infection after intervention with ribavirin or alteration in immunosuppressive therapy. Ten recipients developed prolonged or persistent infection. Transaminitis was common, but short-term morbidity was rare; only one recipient developed apparent but clinically mild post-transfusion hepatitis.

INTERPRETATION

Our findings suggest that HEV genotype 3 infections are widespread in the English population and in blood donors. Transfusion-transmitted infections rarely caused acute morbidity, but in some immunosuppressed patients became persistent. Although at present blood donations are not screened, an agreed policy is needed for the identification of patients with persistent HEV infection, irrespective of origin, so that they can be offered antiviral therapy.

FUNDING

Public Health England and National Health Service Blood and Transplant.

Indigenous hepatitis E in England and wales from 2003 to 2012: evidence of an emerging novel phylotype of viruses

BACKGROUND

Enhanced surveillance and molecular characterisation studies of hepatitis E virus (HEV) in England and Wales have been undertaken since 2003. The dynamics of hepatitis E have changed recently with an increase in the number of indigenous cases and an observed viral shift.

METHODS

HEV antibody and RNA data were analysed to ascertain the annual number of acute infections, the HEV genotype disposition and viral phylogeny. These data were investigated in the context of collected travel history and demographic data.

RESULTS

In total, 2713 acute hepatitis E cases were diagnosed, of which 1376 were indigenous infections. Travel associated cases remained steady and mainly associated with Genotype 1 infections. In contrast, major fluctuations were noted in indigenously-acquired cases with a dramatic year on year increase during 2010-2012. Molecular characterisation demonstrated indigenous infections to cluster into two distinct phylogenetic groups with the emergence of a novel group of Genotype 3 viruses coinciding with the recent increase in cases.

CONCLUSIONS

HEV infection rates are dynamic in England and Wales, influenced by changing trends in indigenously-acquired cases. The recent increase in indigenous cases and the emergence of indigenous viruses not commonly circulating prior to 2010 suggest that the risk of acquiring HEV has changed.

The epidemiology of hepatitis B virus infection in HIV-infected and HIV-uninfected pregnant women in the Western Cape, South Africa

OBJECTIVES

Persistent hepatitis B virus (HBV) infection is a major cause of morbidity and mortality in sub-Saharan Africa. The HIV epidemic has the potential to affect its biology. Immunisation protocols established in the pre-HIV era are based upon data showing predominantly horizontal infant transmission. This study aimed to determine whether HIV co-infection will change the epidemiology of HBV both by increasing infectivity and by favouring the escape of viruses bearing phenotypically altered HBsAg.

METHODS

This retrospective cross-sectional study used antenatal samples from the 2008 Antenatal Sentinel HIV and Syphilis Prevalence Survey in the Western Cape, South Africa. All HIV-infected women were age and race-matched to HIV-uninfected women. Samples were tested for serological markers of HBV and HDV infection. HBV viral load, consensus sequencing and genotyping were performed. Luminex technology was used to determine HBsAg phenotype. All samples from HIV-infected women were tested for traces of antiretroviral drugs by mass spectrometry.

RESULTS

This study showed a trend toward loss of immune control of HBV in HIV-infected women with 3.4% of samples containing HBsAg, 18.9% contained HBeAg. In contrast, 2.9% of samples from HIV-uninfected women contained HBsAg and 17.1% of these HBeAg. The median HBV load in the HIV-infected group was 9.72×10(7)IU/ml and in the HIV-uninfected group 1.19×10(6)IU/ml. Genotyping showed 63/68 samples belonged to genotype A and the remainder genotype D. Mutations in the precore region were found in 35% and 33% of samples from HIV-infected and HIV-uninfected respectively. Although no major epitope ablation was found, marked variation in HBsAg profiles in HIV-infected group was demonstrated. No HDV infection was detected.

CONCLUSION

HIV-HBV co-infected women exhibit a degree of immune escape. One in six HBV-infected pregnant women, irrespective of HIV status is HBeAg seropositive. HBV immunization of newborns in sub-Saharan Africa should be implemented.

The 'Red Queen' dilemma--running to stay in the same place: reflections on the evolutionary vector of HBV in humans

BACKGROUND

Estimates for the evolutionary rate of HBV until now have been interpreted as showing that HBV is a relatively recent acquisition for mankind. The existence of defined HBV genotypes is thought to represent past founder effects. We have explored virus mutation in a group of 48 persistently infected blood donors sampled at two points in time and suggest otherwise.

METHODS

HBV-infected donors were detected by hepatitis B surface antigen (HBsAg) screening and staged by hepatitis B e markers. Serum DNA from those persistently infected with HBV was characterized by consensus sequencing and the amino acid sequences inferred. These were compared against consensus genotype sequences and divergence measured at two points in time.

RESULTS

Rates of viral mutation were higher across both HBsAg and hepatitis B core antigen in the group of donors seropositive for hepatitis B e antibody (1.36×10⁻³ and 1.54×10⁻³ changes per residue per year, respectively) than in those seropositive for hepatitis B e antigen (4.59×10⁻⁴ and 6.62×10⁻⁴ changes per residue per year, respectively). Codon mutations reverting to the genotype consensus were commonly seen. Codon changes were clustered close to the C-terminal region of HBsAg and were accommodated in overlapping polymerase by synonymous substitutions.

CONCLUSIONS

It is suggested that in vivo HBV behaves as a self-normalizing meme and mutational rates, although high, do not lead to significant change over time in a persistent infection. This would be compatible with co-evolution within its human host and introduction within humans being an ancient occurrence.

Evaluation of an ethidium monoazide-enhanced 16S rDNA real-time polymerase chain reaction assay for bacterial screening of platelet concentrates and comparison with automated culture

BACKGROUND

Culture-based systems are currently the preferred means for bacterial screening of platelet (PLT) concentrates. Alternative bacterial detection techniques based on nucleic acid amplification have also been developed but these have yet to be fully evaluated. In this study we evaluate a novel 16S rDNA polymerase chain reaction (PCR) assay and compare its performance with automated culture.

STUDY DESIGN AND METHODS

A total of 2050 time-expired, 176 fresh, and 400 initial-reactive PLT packs were tested by real-time PCR using broadly reactive 16S primers and a "universal" probe (TaqMan, Invitrogen). PLTs were also tested using a microbial detection system (BacT/ALERT, bioMérieux) under aerobic and anaerobic conditions.

RESULTS

Seven of 2050 (0.34%) time-expired PLTs were found repeat reactive by PCR on the initial nucleic acid extract but none of these was confirmed positive on testing frozen second aliquots. BacT/ALERT testing also failed to confirm any time-expired PLTs positive on repeat testing, although 0.24% were reactive on the first test. Three of the 400 "initial-reactive" PLT packs were found by both PCR and BacT/ALERT to be contaminated (Escherichia coli, Listeria monocytogenes, and Streptococcus vestibularis identified) and 14 additional packs were confirmed positive by BacT/ALERT only. In 13 of these cases the contaminating organisms were identified as anaerobic skin or oral commensals and the remaining pack was contaminated with Streptococcus pneumoniae.

CONCLUSION

These results demonstrate that the 16S PCR assay is less sensitive than BacT/ALERT and inappropriate for early testing of concentrates. However, rapid PCR assays such as this may be suitable for a strategy of late or prerelease testing.

The rise and fall of XMRV

Due to the relatively recent emergence of the human T-lymphotropic and the human immunodeficiency viruses, enthusiasm for the identification of novel viruses, especially retroviruses, with pathogenic potential in humans, remains high. Novel technologies are now available with the ability to search for unknown viruses, such as gene arrays and new generation sequencing of tissue and other samples. In 2006, chip technology identified a novel retrovirus in human prostate cancer (PCa) tissue samples. Due to close homology to a mouse retrovirus, the virus was named xenotropic murine leukaemia virus-related virus (XMRV). Ever since the initial disease association with PCa, XMRV has stirred a lot of attention and concern worldwide for the medical community, public health officials and in particular global transfusion services. Public response, in this new era of electronic communication and advocacy was rapid, wide and unprecedented. In this review, we outline the course of biomedical research efforts that were put forward internationally in the process of determining the risk to the human population, the response of the blood banking community and review the current state of knowledge of xenotropic murine retroviruses. Although XMRV is no longer regarded as an infection of humans, a lesson was learnt in modern virology that holds deeper implications for biomedical research, particularly stem cell generation and transplantation practices.

Therapy-induced clearance of HCV core antigen from plasma predicts an end of treatment viral response

During viral assembly, viral proteins are released into plasma and can be used to infer viral load. The Architect hepatitis C virus (HCV) core antigen (Ag) assay is a potential alternative to HCV RNA quantification for measuring response to therapy and predicting an end of treatment viral response (EOTR). The HCVp22Ag assay was used to infer viral load in 68 window RNA-containing samples and in 284 samples from baseline to week 14 of ribavirin/interferon treatment in 23 patients with EOTR including three who relapsed, 20 not achieving EOTR and 11 controls. HCV Ag and RNA correlated well (r = 0.86) with linear dose responses on dilution. In patients on therapy and control patients, plasma HCV antigen was detected in 51 of 54 with an interpolated LOD cut off between 10(3) and 10(4) RNA IU/mL. Plasma HCV antigenaemia and plasma RNA levels were significantly different in EOTR from non-EOTR patients at 3 days after treatment start and all times thereafter. Positive and negative EOTR predictive values for HCV RNA >2 log drop and HCV Ag loss at 12 weeks were 70% and 74%, 85% and 93% respectively. HCV Ag reactivity has a linear dose response independent of genotype and correlates well with HCV RNA. The failure to clear HCV Ag is as accurate as the failure to clear HCV RNA at twelve weeks into therapy in predicting the likelihood of failure to achieve EOTR. HCV Ag potentially offers a convenient alternative to RNA measurement for defining a futility flag in HCV therapy.

The diversity and management of chronic hepatitis B virus infections in the United Kingdom: a wake-up call

BACKGROUND

Through migration, diversity of chronic hepatitis B virus (HBV) infection has changed, affecting disease burden and control. We describe clinical and viral characteristics of chronic HBV in the United Kingdom.

METHODS

A total of 698 individuals with chronic HBV infection were recruited from referral liver centers. Demographic, clinical, and laboratory data were collected.

RESULTS

Sixty-one percent of patients were male, 80% were not born in the United Kingdom, and the largest ethnicity was East/Southeast Asian (36%). Twenty-two percent were hepatitis B e antigen (HBeAg) seropositive; 20.4% (59/289) had cirrhosis and 10 (1.7%) had hepatocellular carcinoma. Genotype D was most common (31%) followed by A, C, B, and E (20%, 20%, 19%, and 9%, respectively). Genotype was significantly associated with country of birth, length of time in the United Kingdom, HBeAg status, and precore and basal core promoter mutations. One-third were on treatment, with men independently more likely to be treated. Only 18% of those on treatment were on recommended first-line therapies, and 30% were on lamivudine monotherapy. Among treated individuals, 27% had antiviral drug resistance. Testing rates for human immunodeficiency virus, hepatitis C virus, and delta coinfections were low.

CONCLUSIONS

We demonstrated diversity of chronic HBV infections in UK patients, suggesting that optimal management requires awareness of the variable patterns of chronic HBV in countries of origin. We also found less-than-optimal clinical management practices, possible gender-based treatment bias, and the need to improve testing for coinfections.

Investigating the impact of hepatitis B virus surface gene polymorphism on antigenicity using ex vivo phenotyping

The hepatitis B virus (HBV) surface antigen (HBsAg) is a complex protein, and understanding accurately the impact of amino acid changes on the antigenicity of the immunodominant a determinant must take this complexity into consideration. Epitope mapping with four mAbs was used to phenotype HBsAg directly from patients’ sera to investigate the effect of mutations in their native genetic backbone. The expected mAb reactivity was established initially for samples harbouring ‘wild-type’ HBsAg sequences across genotypes A–E. The alteration of HBsAg antigenicity, defined by mAb epitope loss, was demonstrated in a number of samples with sequence-inferred amino acid changes. Individual mutations within the mapped epitopes to which the mAbs were directed usually affected their binding. However, the loss of more than one epitope was observed as the number of mutations within a sequence increased. Conversely, not all mutations occurring in the a determinant altered the HBsAg conformation. The genotype backbone, the specific amino acid substitution and amino acid changes occurring outside the major antigenic region appeared to be important in determining expression of the predicted epitope loss. These data clearly demonstrate that sequence-based methods alone may not accurately define HBsAg phenotype. This phenotyping methodology allows for the rapid and accurate identification of antigenically altered viruses and will greatly enhance current HBV surveillance, research and diagnostic activities. The data generated can be used to inform on public health issues relating to prevalence, transmission and impact of HBsAg mutants in HBV-infected populations.