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

Absence of chronicity in infants born to immunized mothers with occult HBV infection in Taiwan

BACKGROUND & AIMS

In the Taiwanese population born in the universal vaccination era, HBsAg carrier rates have fallen below 2%, while approximately 5% develop occult hepatitis B infection (OBI). However, the potential for transmission from mothers with OBI to their infants has not been well studied. We aimed to investigate whether mothers with OBI could transmit HBV to their babies.

METHODS

A total of 253 pregnant women who were born after July 1986 and had been fully vaccinated against HBV during infancy were recruited from a tertiary hospital in Northern Taiwan. HBV serology and DNA levels were determined. Babies born to mothers with OBI were followed-up until 1 year of age. The surface genes were sequenced.

RESULTS

HBV infection was documented in 18 vaccinated mothers, 2 of whom were HBsAg-reactive (0.79 %). Seventeen were positive for HBV DNA, among whom 16 (6.32%) presented with OBI with a median DNA level of 145 IU/ml (interquartile range: 37.8-657.3 IU/ml). Eleven babies born to 10 mothers with OBI were recruited. Three babies were HBsAg-reactive, and 2 were positive for HBV DNA (17.0 and 212.0 IU/ml). Seven mothers with OBI carried multiple surface gene variants. Two transiently infected babies harbored variants originating from their mother's HBV quasi-species. All infants received complete hepatitis B vaccines. At 12 months of age, none of the babies were positive for HBsAg or HBV DNA.

CONCLUSIONS

It was possible for mothers with OBI to transmit HBV to their babies, who consequently harbored surface gene variants originating from their mothers' minor variants. Viremia was cleared 1 year after completing the hepatitis B vaccination series.

LAY SUMMARY

Since initiating the hepatitis B vaccination program in Taiwan, the rate of young individuals (i.e. born after 1986) carrying the HBV surface antigen has fallen below 2%, although around 5% of vaccinated individuals develop occult HBV infections. Herein, we show that pregnant mothers with occult HBV infections can transmit HBV to their offspring. However, no infant had sustained infection at 1 year of age having completed a full HBV vaccination series.

Global prevalence and phylogeny of hepatitis B virus (HBV) drug and vaccine resistance mutations

Vaccination and anti-viral therapy with nucleos(t)ide analogues (NAs) are key approaches to reducing the morbidity, mortality and transmission of hepatitis B virus (HBV) infection. However, the efficacy of these interventions may be reduced by the emergence of drug resistance-associated mutations (RAMs) and/or vaccine escape mutations (VEMs). We have assimilated data on the global prevalence and distribution of HBV RAMs/VEMs from publicly available data and explored the evolution of these mutations. We analysed sequences downloaded from the HBV Database and calculated prevalence of 41 RAMs and 38 VEMs catalogued from published studies. We generated maximum likelihood phylogenetic trees and used treeBreaker to investigate the distribution and estimated the age of selected mutations across tree branches. RAM M204I/V had the highest prevalence, occurring in 3.8% (109/2838) of all HBV sequences in our data set, and a significantly higher rate in genotype C at 5.4% (60/1102, p = 0.0007). VEMs had an overall prevalence of 1.3% (37/2837) and had the highest prevalence in genotype C and in Asia at 2.2% (24/1102; p = 0.002) and 1.6% (34/2109; p = 0.009), respectively. Phylogenetic analysis suggested that RAM/VEMs can arise independently of treatment/vaccine exposure. In conclusion, HBV RAMs/VEMs have been found globally and across genotypes, with the highest prevalence observed in genotype C. Screening for genotype and for resistance-associated mutations may help to improve stratified patient treatment. As NAs and HBV vaccines are increasingly being deployed for HBV prevention and treatment, monitoring for resistance and advocating for better treatment regimens for HBV remains essential.

Evaluation of Four Rapid Tests for Detection of Hepatitis B Surface Antigen in Ivory Coast

Background

Hepatitis B virus (HBV) infection is a leading cause of liver disease worldwide. Hepatitis B surface antigen (HBsAg) rapid diagnostic tests (RDTs) could be an ideal tool for a large-scale HBV screening in settings with high endemicity but limited infrastructure. The aim of this study was to evaluate the diagnosis performance of such RDTs for screening HBV infection in Ivory Coast.

Methods

From September 2018 to January 2019, a cross-sectional phase I evaluation study of RDTs was conducted in three laboratories of Abidjan (CeDReS, CNTS and IPCI), on a panel of 405 whole blood samples and 699 plasmas. Four HBsAg RDTs (Determine™ HBsAg, SD Bioline HBsAg WB®, Standard Q HBsAg® and Vikia HBsAg®) were evaluated. The diagnostic performance (sensitivity and specificity) was calculated in comparison to the reference sequential algorithms of two EIA tests (Dia.Pro HBsAg® one version ULTRA and Monolisa™ HBsAg ULTRA).

Results

The Determine™ HBsAg and Vikia HBsAg® tests performed well, with 100% of sensitivity, specificity both on plasma and on whole blood. For SD Bioline HBsAg WB® and Standard Q HBsAg®, the specificities were 99.8% and the sensitivities 99.3% and 97.1% respectively. Finally, there were a total of 19 false negative results: 3 with SD Bioline HBsAg WB® and 16 with Standard Q HBsAg®.

Conclusion

Determine HBsAg® from Alere and Vikia HBsAg® from Biomérieux are the most suitable RDTs for screening for HBV in Ivory Coast. A phase II evaluation must be initiated.

Establishment of a Seronegative Occult Infection With an Active Hepatitis B Virus Reservoir Enriched of Vaccine Escape Mutations in a Vaccinated Infant After Liver Transplantation

We describe the establishment of a seronegative occult hepatitis B virus (HBV) infection (OBI) in a successfully vaccinated infant who underwent liver transplantation from an donor positive for antibody to hepatitis B core antigen (anti-HBc). The use of highly sensitive droplet digital polymerase chain reaction assays revealed a not negligible and transcriptionally active intrahepatic HBV reservoir (circular covalently closed DNA, relaxed circular DNA, and pregenomic RNA: 5.6, 2.4, and 1.1 copies/1000 cells, respectively), capable to sustain ongoing viral production and initial liver damage. Next-generation sequencing revealed a peculiar enrichment of hepatitis B surface antigen vaccine-escape mutations that could have played a crucial role in OBI transmission. This clinical case highlights the pathobiological complexity and the diagnostic challenges underlying OBI.

A chronic hepatitis B patient infected with HBsAg diagnostic-escape strain in the presence of anti-HBs positivity

Hepatitis B virus (HBV) is an important pathogen responsible for serious diseases like chronic hepatitis, cirrhosis and liver cancer. Turkey is located in the intermediate endemic region based on the average HBV surface antigen positivity. The high replication capacity of HBV and the lack of proofreading activity of the reverse transcriptase (RT) enzyme makes the virus prone to mutations. In this study, S gene mutation which is detected in a chronic HBV case without any follow-up and treatment is presented. Although patient was HBsAg negative and anti-HBs positive in the examinations, the mutation analysis was performed upon the high level of HBV DNA load and sG145R (vaccine escape) mutation in S gene region and rtI169F, rtV173L, rtA181G and rtT184R mutations in pol gene region were detected. S gene region mutations may cause false negatives in diagnostic assays that detect HBsAg. At the same time, it is a public health problem because these HBV variants can also be transmitted by vertical and horizontal routes. Therefore, when atypical serological profiles are encountered, it is of utmost importance to remember S gene mutations and perform necessary analyses.

Hepatitis B Vaccine and Immunoglobulin: Key Concepts

Hepatitis B virus (HBV) immunization is safe and has been accepted worldwide as a routine practice. The target of such vaccination is to induce the immune response in the host, resulting in the prevention of replication of HBV. There are several immunological and clinical factors which determine the clinical efficacy and safety of the HBV vaccine. In this article we have highlighted the response of the host immune system to HBV vaccination (immunogenicity), efficacy, and safety of the vaccine, issues with booster dosing, paths of development (preclinical and clinical) of the HBV vaccine, novel and upcoming strategies for improvement of HBV vaccination, and the concept of therapeutic HBV vaccination. The different aspects and regulatory recommendations pertaining to HBV vaccine development are also discussed. The new strategies for improvement of HBV vaccination include pre-S1 and pre-S2 portions of the HBV surface antigen, increasing the antigen dose, accelerated vaccination schedules, alternative vaccination route, use of adjuvants like immunostimulatory DNA sequences, etc. Therapeutic vaccination is being explored for initiation of a multifunctional and multispecific T cell response against the major HBV antigens and also effective activation of humoral immunity for viral control.

Molecular epidemiology of hepatitis B virus mutants associated with vaccine escape, drug resistance and diagnosis failure

The massive implementation of the vaccine and antiviral agents against hepatitis B virus (HBV), targeting the envelope and viral polymerase genes, induces a selection pressure that might lead to the emergence of variants that impair the effectiveness of the vaccine, diagnostic methods and antiviral therapy. The aim of this study was to evaluate the prevalence of HBV vaccine escape mutants (VEMs), diagnostic failure mutants (DFMs) and treatment resistance mutants (ARMs) among individuals from Buenos Aires, Argentina. HBV surface antigen and polymerase sequences obtained from serum samples of 530 HBV-infected individuals were analysed. Samples belonged to genotypes A (28.1%), D (13.6%) and F (58.3%). VEMs, DMFs and ARMs were present in 40 (7.5%), 57 (10.7%) and 27 (5.1%) samples within the studied population. Additionally, eight nonpreviously reported VEMs and nine DFMs were identified. VEMs and DFMs were biased by genotype, being higher in genotype D (33.3% and 33.3%) compared to genotype A (6% and 17.4%) and genotype F (2.3% and 2.3%) (P > 0.001). On the contrary, there was no association between the presence of ARMs and HBV genotype (P = 0.324). VEMs, DFMs and ARMs create public health concerns. The current study provided valuable information about mutants in surface antigen and polymerase in HBV-infected patients from Argentina where HBV-F is the most prevalent genotype. Consequently, it constitutes an important reference for Latin American clinicians in order to optimize the management of HBV-infected patients.

Reactivation of a Vaccine Escape Hepatitis B Virus Mutant in a Cambodian Patient During Anti-Hepatitis C Virus Therapy

A 76-year-old Cambodian man co-infected with hepatitis B virus (HBV) and hepatitis C virus (HCV) 6c-1 presented for care. HBV DNA was intermittently detectable despite anti-HBs levels being above the protective threshold. During treatment for HCV, HBV DNA levels increased. Sequencing revealed multiple mutations including vaccine escape mutation and mutations predicted to enhance fitness. This case represents exacerbation of an HBV vaccine escape mutant during a direct-acting antiviral therapy.

Could resistant and escape variants of hepatitis B virus be a problem in the future?

Aim: Nucleos(t)ide analogs have a risk for the development of Polymerase gene mutations and they can cause compensatory mutations in the HBV surface gene. Alteration in the ‘a determinant’ of the s gene predispose for escape mutants. We aimed to evaluate primary, compensatory and escape mutations in chronic hepatitis B. Materials & methods: Two hundred nineteen specimens were obtained and HBV pol gene region was sequenced and amplified and HBV pol/s gene mutations were determined. Results: We detected primary mutation in 29.8% patients. Compensatory mutations were detected in 50.3%patients. Hepatitis B Immunoglobulin escape mutations, vaccine escape mutations, Hepatitis B diagnosis-escape and immunoselected amino acid substitutions were observed in 9.6%, 6.9%, 5.2% and 11.9% of patients, respectively. Antiviral drug-associated potential vaccine-escape mutants were detected in 17.9% patients. Conclusion: Therefore, epidemiological and demographical changes may be possible. Therefore, the typical HBsAg mutants and antiviral drug-associated potential vaccine-escape mutants should be monitored carefully.

What is changed in HBV molecular epidemiology in Italy?

Hepatitis B virus (HBV) infection represents the most common cause of chronic liver diseases worldwide. Consequently, to the introduction of the universal HBV vaccination program, the prevalence of hepatitis B surface antigen was markedly reduced and less than 1% of the population of Western Europe and North America is chronically infected. To date, despite great advances in therapeutics, HBV chronic infection is considered an incurable disease. Ten hepatitis B virus genotypes (A-J) and several subgenotypes have been identified so far, based on intergroup divergences of 8% and 4%, respectively, in the complete viral genome. HBV-D genotype has been found throughout the world, with highest prevalence in the Mediterranean area. In the present review, several articles concerning HBV epidemiology, and phylogeny in Italy have been analyzed, mainly focusing on the changes occurred in the last decade.

Detection of HBsAg mutants in the blood donor population of Pakistan

BACKGROUND

Infection with the Hepatitis B virus (HBV) continues to be one of the leading healthcare issues in Pakistan, affecting over 6 million people. The existence of HBsAg mutants is well documented in many countries. In Pakistan, HBV screening in the majority of the blood banks is performed by Rapid Detection Devices or ELISA tests. These tests are designed to detect HBsAg, but may not detect the mutant HBsAg. Failure to detect the HBsAg mutant may result in the transmission of HBV infection from donor to recipient. Hence, there is a need to identify a HBsAg assay which can detect mutants in a country where simple and conventional HBsAg assays with varying sensitivity and specificity are used to detect HBV infections.

MATERIAL AND METHODS

Three routinely used diagnostic tests (Rapid Detection Devices, ELISA and CLIA) for HBsAg were compared with the LIAISON® XL Murex HBsAg Quant Assay to determine the prevalence of HBV mutants in the Pakistani blood donor population. The samples of blood donors from different cities of Pakistan were collected. The testing was performed using SD Bioline rapid assay (n = 1500), ELISA (n = 1500), and Abbott ARCHITECT®CLIA system (n = 1500) at the centers where the donations were collected. All samples (n = 4500) were re-tested for comparative analysis on the LIAISON® XL Murex HBsAg Quant assay (DiaSorin S.p.A.). PCR testing was performed as a gold standard on all discordant samples.

RESULTS

119/4500 (2.64%) of the samples were positive for antibodies against HBsAg. The sensitivity of SD Bioline Rapid, GB HBsAg ELISA, Abbott ARCHITECT® and LIAISON® XL Murex HBsAg Quant assay was 17.24%, 43.75%, 90.91%and 100% respectively. The specificity of SD Bioline Rapid, GB HBsAg ELISA, Abbott ARCHITECT® and LIAISON® XL Murex HBsAg Quant Assay was 98.82%, 99.59%, 100% and 100%, respectively.

CONCLUSION

LIAISON® XL Murex HBsAg Quant assay is a highly sensitive, specific and accurate screening assay for detecting wild type as well as mutant HBsAg.

Ultra-deep sequencing reveals high prevalence and broad structural diversity of hepatitis B surface antigen mutations in a global population

The diversity of the hepatitis B surface antigen (HBsAg) has a significant impact on the performance of diagnostic screening tests and the clinical outcome of hepatitis B infection. Neutralizing or diagnostic antibodies against the HBsAg are directed towards its highly conserved major hydrophilic region (MHR), in particular towards its “a” determinant subdomain. Here, we explored, on a global scale, the genetic diversity of the HBsAg MHR in a large, multi-ethnic cohort of randomly selected subjects with HBV infection from four continents. A total of 1553 HBsAg positive blood samples of subjects originating from 20 different countries across Africa, America, Asia and central Europe were characterized for amino acid variation in the MHR. Using highly sensitive ultra-deep sequencing, we found 72.8% of the successfully sequenced subjects (n = 1391) demonstrated amino acid sequence variation in the HBsAg MHR. This indicates that the global variation frequency in the HBsAg MHR is threefold higher than previously reported. The majority of the amino acid mutations were found in the HBV genotypes B (28.9%) and C (25.4%). Collectively, we identified 345 distinct amino acid mutations in the MHR. Among these, we report 62 previously unknown mutations, which extends the worldwide pool of currently known HBsAg MHR mutations by 22%. Importantly, topological analysis identified the “a” determinant upstream flanking region as the structurally most diverse subdomain of the HBsAg MHR. The highest prevalence of “a” determinant region mutations was observed in subjects from Asia, followed by the African, American and European cohorts, respectively. Finally, we found that more than half (59.3%) of all HBV subjects investigated carried multiple MHR mutations. Together, this worldwide ultra-deep sequencing based genotyping study reveals that the global prevalence and structural complexity of variation in the hepatitis B surface antigen have, to date, been significantly underappreciated.

Influences of obesity on the immunogenicity of Hepatitis B vaccine

OBJECTIVE

Hepatitis B vaccine is regarded as the most effective method for the prevention of hepatitis B virus (HBV) infection. However, several factors such as age, body mass index and immunocompetent state have been reported to be associated with reduced immunization responses. The present commentary was aimed to discuss the influences of obesity on the immunogenicity of hepatitis B vaccines.

DATA SOURCES

Available peer-reviewed literatures, practice guidelines, and statistics published on hepatitis B vaccine in obesity between 1973 and 2015.

CONCLUSIONS

Obesity was significantly associated with non-response to hepatitis B vaccine immunization. The risk of nonresponsiveness of hepatitis B vaccine among obese people increased with BMI. Moreover, the obesity might lead to an increased risk of HBV vaccine-escape mutations. The mechanism responsible for decreased immunization responses in obesity included leptin-induced systemic and B cell intrinsic inflammation, impaired T cell responses and lymphocyte division and proliferation. Therefore, more studies should be performed to analyze the influences of obesity on the immunogenicity of hepatitis B vaccines to improve the immunoprotecive effect of hepatitis B vaccines in future.

HIV therapy with unknown HBV status is responsible for higher rate of HBV genome variability in Ethiopia

BACKGROUND

In Ethiopia, HBV and HIV are co-circulating. Since patients are not routinely tested for HBV, the use of antiretroviral drugs could contribute to unintended HBV drug resistance and surface gene variability during HIV coinfection.

METHODS

A total of 161 hepatitis B surface antigen (HBsAg)-positive sera from 58 HIV-coinfected and 103 drug-naive HBV-monoinfected individuals were characterized for HBV drug resistance and immune escape HBsAg variants. HBV polymerase/surface gene fragment of 716 bp was analysed by direct sequencing.

RESULTS

In 34 out of 161 study subjects (21.1%) HBV drug resistance mutations (DRMs) were detected with a frequency of 3.1% rtL80F/I, 0.6% rtA181V, 1.2% rtT184S, 6.2% rtV173L, 10.6% rtL180M, 10.6% rtM204V/I and 8.1% rtI233V. The prevalence of the major DRMs in HBV-HIV-coinfected individuals was significantly higher than monoinfected individuals (41.4% versus 10.7%). Lamivudine selected DRMs, that is, rtL180M (29.3%) and rtM204V/I (29.3%) and rtV173L (15.5%) were more prevalent in HBV-HIV-coinfected individuals but absent in HBV-monoinfected individuals. Despite the finding that rtL180M and rtM204V/I were higher among ART-experienced individuals, the overall prevalence of DRMs (48.0% versus 36.4%) showed no significance difference among antiretroviral therapy (ART) status. The study also revealed higher frequency and heterogeneity of putative and known immune escape HBsAg mutations both in the major hydrophilic region (MHR; 68.3%) and outside the MHR (82.5%) of the surface gene. In particular, the 'a' determinant surface gene mutations (sT125S, sA128V, sQ129H/R, sT131I, sC137S, sT143M, sD144D/E, sG145R, sT148P) and the majority of clustered/multiple as well as drug selected immune escape HBsAg mutations were more prevalent in HBV-HIV-coinfected individuals.

CONCLUSIONS

HIV therapy without HBV co-management in Ethiopia fosters emergence and circulation of HBV variants of public health importance. It is highly recommended to include HBV testing and co-management as part of routine HIV care programmes for a better ART selection.

Clinical significance of hepatitis B surface antigen mutants

Hepatitis B virus (HBV) infection is a major public health problem in many countries, with nearly 300 million people worldwide carrying HBV chronic infection and over 1 million deaths per year due to cirrhosis and liver cancer. Several hepatitis B surface antigen (HBsAg) mutations have been described, most frequently due to a single amino acid substitution and seldom to a nucleotide deletion. The majority of mutations are located in the S region, but they have also been found in the pre-S1 and pre-S2 regions. Single amino acid substitutions in the major hydrophilic region of HBsAg, called the “a” determinant, have been associated with immune escape and the consequent failure of HBV vaccination and HBsAg detection, whereas deletions in the pre-S1 or pre-S2 regions have been associated with the development of hepatocellular carcinoma. This review article will focus on the HBsAg mutants and their biological and clinical implications.

Evolution and mutations of hepatitis B virus quasispecies in genotype B and C during vertical transmission

Evolution patterns of HBV QS between genotype B and C during vertical transmission are not well understood. In this study, we enrolled 10 HBV infected mother-infant pairs (four pairs with genotype B, four pairs with genotype C, and two with co-infection) without anti-viral therapy. Serum HBV DNA of mothers and infants were sequenced, HBV QS complexity and diversity were analyzed, polymorphisms and mutation sites were recorded, and phylogenetic trees were performed. Our result showed that the QS complexities in P (amino acid), C/PreC (amino acid), and PreS1 (nucleotide) gene were significantly higher in mothers than in infants in pairs with genotype C (P < 0.05), however, full-length and other genes showed non-significant differences (P > 0.05). Unlike genotype C, QS complexity of P gene (nucleotide) was significantly higher in infants than in mothers (P < 0.05) in pairs with genotype B, similarly, QS complexities of full-length and other genes (except Pre S2) were also higher in infants than in mothers but without significant differences (P > 0.05). QS diversities of full-length and most genes in genotype B were comparable between mothers and their infants (P > 0.05), in pairs with genotype C, dS of P, X, RT genes, genetic distance of Pre S1 gene (amino acid) and dN of Pre S1 gene were significant higher in mothers than in infants (P < 0.05). Several HBV mutations correlated with immune escape, e antigen loss and drug resistance were observed in infants. The results indicated that differences of HBV QS evolution patterns between genotype B and C during vertical transmission might contribute to distinct prognosis.

The prevalence of mutations in the major hydrophilic region of the surface antigen of hepatitis B virus varies with subgenotype

Mutations in the major hydrophilic region (MHR) of the surface antigen of hepatitis B virus (HBV) may result in vaccine escape, failure of immunotherapy and antiviral resistance. These mutants may be transmitted and constitute a public health threat. We aimed to determine the prevalence of MHR mutations of HBV in areas of high endemicity in Guangxi, China. HBV surface gene was analysed from 278 HBsAg-positive asymptomatic individuals recruited from Guangxi using cluster sampling. Three genotypes, B, C and I, were identified. The overall prevalence of MHR mutations is 17·6%. The prevalence of MHR mutations in genotype B (15·1%) is not significantly different from that in genotype C (16·4%). However, the prevalence in subgenotype C5 (31·1%) is significantly higher than in subgenotype C2 (13·0%) (χ2= 6·997,P< 0·05). The prevalence of escape mutations and overlapping polymerase substitutions in subgenotype C5 is significantly higher than in subgenotypes B2 and C2. In total, 7·9% of MHR mutants are escape mutations and 72·1% of MHR mutations produced amino-acid changes in the overlapping polymerase, including resistance mutations to entecavir. Our results suggest that the prevalence of MHR mutations varies with subgenotype. The prevalence of escape mutations and polymerase mutations may be associated with subgenotype.

Molecular epidemiology of hepatitis B virus in Córdoba, Argentina

BACKGROUND

The analysis of the genomes of hepatitis B virus (HBV) identifies phylogenetic variants called genotypes, which may lead to distinct biological and clinical behaviors.

OBJECTIVES

The aim of this study was to describe the current molecular epidemiology and genetic diversity of HBV in Córdoba, Argentina.

STUDY DESIGN

A total of 52 HBV samples, 40 from HBV mono-infected and 12 from human immunodeficiency virus (HIV)-HBV co-infected patients, were sequenced in the S gene and in the basal core promoter-precore (BCP-pC) region.

RESULTS

Presence of subgenotypes F1b (35%) and F4 (17.5%), subgenotype A2 (37.5%), C (5.0%) (subgenotype could not be defined) and D (5.0%) (subgenotype D2, and the other could not be defined) were observed among mono-infected patients. The co-infected individuals displayed a different genotype distribution: sub-genotype A2 was the most common (75.0%), followed by subgenotype F1b (25.0%).

CONCLUSIONS

These results showed two epidemiologic scenarios: the mono-infected population may represent the ethnic composition of the current human population of Córdoba, where the Amerindian (genotype F) and European origins (subgenotype A2) account for the 90% of the samples; for the co-infected patients, the high prevalence of subgenotype A2 resemble previous analyses from Buenos Aires. In addition, mutations in hepatitis B surface antigen (HBsAg), polymerase and BCP-pC regions were identified, mainly in chronic or co-infected patients.

Does hepatitis B virus (HBV) genotype influence the clinical outcome of HBV infection?

Between 5 and 10% of adults infected with the hepatitis B virus (HBV) develop a chronic infection lasting longer than 6 months, which may lead to advanced liver disease. HBV can be classified into six genotypic families: A, B, C, D, E and F, but only genotypes A and D are significantly represented in western Europe, where they account for some 90% of cases of infection with HBV. In the present study, we investigated a possible association between HBV genotype A or D and clinical outcome of the infection. We compared the prevalence of these genotypes in a group of patients with chronic active hepatitis to that of a group with acute resolving hepatitis. In patients with chronic active hepatitis, genotype A was found in 28 of 35 patients and genotype D in only four. The remaining three patients were infected with genotype non-A, non-D. In contrast, genotype D was found in 24 of 30 patients with acute hepatitis, whilst genotype A was found in only three patients of this group. Three were infected with genotype non-A, non-D. Our results show a clear association between genotype A and chronic outcome (Ficher's exact test: two-sided P-value, P < 0.0001). They suggest that HBV genotypes may play a role in the virus-host relationship. Possible mechanisms for such a role are discussed.