Global control of hepatitis B virus: does treatment-induced antigenic change affect immunization?

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.

Association between IL28B Polymorphisms and Outcomes of Hepatitis B Virus Infection: A meta-analysis

BACKGROUND

Interleukin (IL) 28B polymorphisms encoding pro-inflammatory and anti-inflammatory cytokines trigger diverse clinical outcome of hepatitis virus infection. However, there is controversy concerning the association of IL28B polymorphisms with the outcome of hepatitis B virus (HBV) infection, with several studies obtaining inconsistent results. We performed a meta-analysis to evaluate the role of 3 single nucleotide polymorphisms (SNPs) rs12979860, rs12980275 and rs8099917 in the progression of HBV infection, overall and by ethnicity.

METHODS

Searched PubMed, Embase and Wiley Online Library electronic databases using 'interleukin 28B', 'IL 28B', 'IL 28B polymorphism', 'hepatitis B virus', 'HBV', and performed meta- analysis for rs12979860, rs12980275 and rs8099917 in Asian and Caucasian populations under the dominant recessive and allele model.

RESULTS

Eighteen studies were found in total and used for this meta-analysis, including 5587 cases and 4295 controls. The IL28B polymorphism rs12979860 had no association with HBV persistence (CC vs CT + TT: OR = 0.86, 95% CI = 0.76-1.00; TT vs CT + CC: OR = 1.14, 95% CI = 0.76-1.70; T vs C: OR = 1.03, 95% CI = 0.94-1.13). Similarly, neither rs12980275 nor rs8099917 had associations with HBV persistence (rs12980275 in AA vs AG + AA: OR = 1.15, 95% CI = 0.96-1.38; rs8099917 in TT vs GT + GG: OR = 1.15, 95% CI = 0.96-1.39). There was also no significant association of IL28B polymorphisms with persistent HBV infection in Asians or Chinese. There was no evidence of an association of rs12979860 with the HBV-related hepatocellular carcinoma susceptibility (T vs C: OR = 1.53, 95% CI = 0.96-2.43).

CONCLUSION

IL28B polymorphisms had no association with the outcome of HBV infection overall, nor in the Asians and the Chinese. These 3 SNPs might not be relevant to the development of HBV infection.

Approximate solutions for HBV infection with stability analysis using LHAM during antiviral therapy

Hepatitis B virus (HBV) is a life-threatening virus that causes very serious liver-related diseases from the family of Hepadnaviridae having very rare qualities resembling retroviruses. In this paper, we analyze the effect of antiviral therapy through mathematical modeling by using Liao's homotopy analysis method (LHAM) that defines the connection between the target liver cells and the HBV. We also examine the basic nonlinear differential equation by LHAM to get a semi-analytical solution. This can be a very straight and direct method which provides the appropriate solution. Moreover, the local and global stability analysis of disease-free and endemic equilibrium is done using Lyapunov function. Mathematica 12 software is used to find out the solutions and graphical representations. We also discuss the numerical simulations up to sixth-order approximation and error analysis using the same software.

Current progress in the prevention of mother-to-child transmission of hepatitis B and resulting clinical and programmatic implications

There is currently no cure for hepatitis B chronic infections. Because new hepatitis B infections result mainly from perinatal transmission, preventing mother-to-child transmission is essential to reach by 2030 the goal of hepatitis B elimination set by the World Health Organization. The universal administration of hepatitis B vaccine to all infants, regardless of maternal status, starting with the birth dose, is the cornerstone of the strategy for elimination. Additional interventions, such as hepatitis B immune globulin administered to newborns and antiviral prophylaxis administered to hepatitis B infected pregnant women, may contribute to reaching the goal earlier. Hepatitis B immune globulin may remain out for reach of many pregnant women in low- and middle-income countries due to cost and logistic issues, but antivirals are cheap and do not require a cold chain for distribution. However, it has been observed that some viruses harbor mutations associated with escape from vaccine-elicited antibodies following immunization or administration of hepatitis B immune globulin. Also, resistance associated mutations have been described for several drugs used for treatment of hepatitis B infected patients as well as for the prevention of mother-to-child transmission. Whether these mutations have the potential to compromise the prevention of mother-to-child transmission or future treatment of the mother is a question of importance. We propose a review of important recent studies assessing tenofovir disoproxil fumarate for the prevention of mother-to-child transmission, and provides detailed information on the mutations possibly relevant in this setting.

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.

Treatment of hepatitis B virus: an update

Chronic hepatitis B virus infection is a global health concern as it affects over 240 million people worldwide and an estimated 686,000 people die annually as a result of complications of the disease. With the development of newer antiviral drugs, viral suppression of HBV is achievable, however elimination of HBV from infected individuals (functional cure) remains an issue. Due to persistence of HBV DNA (cccDNA) in infected cells, chronically infected patients who discontinue therapy prior to HBsAg loss or seroconversion are likely to relapse. Several novel therapeutic strategies are being researched and studied in clinical trials. Here we review these novel strategies to achieve sustained cure or elimination of HBV. These strategies include the targeting of the host or viral factors required for viral persistence as well as therapeutic vaccines.

Models of public-private engagement for health services delivery and financing in Southern Africa: a systematic review

In low- and middle-income countries (LMICs), the private sector-including international donors, non-governmental organizations, for-profit providers and traditional healers-plays a significant role in health financing and delivery. The use of the private sector in furthering public health goals is increasingly common. By working with the private sector through public -: private engagement (PPE), states can harness private sector resources to further public health goals. PPE initiatives can take a variety of forms and understanding of these models is limited. This paper presents the results of a Campbell systematic literature review conducted to establish the types and the prevalence of PPE projects for health service delivery and financing in Southern Africa. PPE initiatives identified through the review were categorized according to a PPE typology. The review reveals that the full range of PPE models, eight distinct models, are utilized in the Southern African context. The distribution of the available evidence-including significant gaps in the literature-is discussed, and key considerations for researchers, implementers, and current and potential PPE partners are presented. It was found that the literature is disproportionately representative of PPE initiatives located in South Africa, and of those that involve for-profit partners and international donors. A significant gap in the literature identified through the study is the scarcity of information regarding the relationship between international donors and national governments. This information is key to strengthening these partnerships, improving partnership outcomes and capacitating recipient countries. The need for research that disaggregates PPE models and investigates PPE functioning in context is demonstrated.

The Association of Pre-S/S Gene Mutations and Hepatitis B Virus Vertical Transmission

BACKGROUND

HBV Pre-S/S gene mutations can occur before or after implementation of combined vaccination program. HBV Prs-S/S gene mutation is a risk factor of vaccination failure and frequently causes HBV vertical transfection.

OBJECTIVES

To assess the association of hepatitis B virus (HBV) S gene mutations with vertical transmission.

PATIENTS AND METHODS

In this prospective nested case-control study, a total of 60 pregnant women with positive serum HBsAg and HBV DNA ≥ 10(7) IU/mL were divided into a case group (15 cases with vaccination failure) and a control group (45 cases with vaccination success) according to whether their infants tested positive for HBV infection. Mothers and their children in the case group were further sub-divided into groups including mothers, newborns and infant (the same newborns at age of seven months). The pre-S/S gene mutations were detected by PCR and sequenced and its association with vertical transmission of HBV was analyzed.

RESULTS

HBV genotype B was the dominant genotype in the both groups' mothers. Each mother-child pair in case group had the same HBV genotype. There were no significant differences in mutation frequencies of HBV Pre-S/S gene between case and control groups' mothers (Fragment 1 (M): 2 vs. 4, P > 0.05; Fragment 2 (M): 10 vs. 10, P > 0.05), or among the mothers, newborns and infants in the case group (Fragment 1 (M): 2, 2, and 3, respectively, P > 0.05; Fragment 2 (M): 10, 10 and 10 respectively, P > 0.05). Mutation site analysis of the both groups' mothers demonstrated 108 different mutation sites in the HBV pre-S/S gene, with 105 silent mutations and 5 missense mutations including ntA826G, ntC531T, ntT667C, ntC512T and ntC546A. Among 15 mother-newborn-infant pairs with successful PCR and sequence in case group, 7 (41.17%) mother-newborn pairs, 9 (60.00%) mother-infant pairs and 3 (20.00%) infant-newborn pairs had different mutation sites.

CONCLUSIONS

HBV in children due to vaccination failure was resulted from vertical transmission. HBV Pre-S/S gene mutations were prevalent and could occur before or after vaccination. Therefore, simply analyzing mutation frequency of HBV gene was not of value. To advance blocking HBV vertical transmission, future studies should focus on specific mutation sites, potentially associated with vaccination failure.

Global elimination of mother-to-child transmission of hepatitis B: revisiting the current strategy

Mother-to-child transmission (MTCT) of hepatitis B virus (HBV) is a major route of HBV transmission worldwide despite an existing immunoprophylaxis regimen. The implementation of immunoprophylaxis has been challenging, especially in low-income and middle-income countries, where MTCT is common, because of difficulty obtaining and delivering the monovalent HBV vaccine and the HBV immunoglobulin. Global control of the HBV epidemic will need improved prevention of MTCT. We discuss research gaps that hinder development of new options for the elimination of MTCT as well as policy changes that may help the current vaccine-based strategy to live up to its full potential. We propose that decreasing hepatitis B viral concentrations before delivery, along with HBV vaccine use, could provide an alternative strategy that would decrease MTCT of HBV.

Hepatitis B virus PreS/S gene variants: pathobiology and clinical implications

The emergence and takeover of hepatitis B virus (HBV) variants carrying mutation(s) in the preS/S genomic region is a fairly frequent event that may occur spontaneously or may be the consequence of immunoprophylaxis or antiviral treatments. Selection of preS/S mutants may have relevant pathobiological and clinical implications. Both experimental data and studies in humans show that several specific mutations in the preS/S gene may induce an imbalance in the synthesis of the surface proteins and their consequent retention within the endoplasmic reticulum (ER) of the hepatocytes. The accumulation of mutated surface proteins may cause ER stress with the consequent induction of oxidative DNA damage and genomic instability. Viral mutants with antigenically modified surface antigen may be potentially infectious to immune-prophylaxed patients and may account for cases of occult HBV infection. In addition, preS/S variants were reported to be associated with cases of fulminant hepatitis as well as of fibrosing cholestatic hepatitis, and they are associated with cirrhosis and hepatocellular carcinoma development.

Mechanisms of hepatitis B virus resistance development

Hepatitis B virus (HBV) resistance to nucleos(t)ide analogue (NA) therapy is essentially structure specific, with each NA falling within three main structural groups. Resistance to each of these is characterized by specific mutations in the reverse transcriptase domains of the HBV polymerase, and may be associated with compensatory mutations which can increase replication. HBV polymerase is considered to have a traditional 'right-handed' structural conformation, and each of the resistance mutations is predicted to cause a specific structural change of the polymerase, thereby preventing incorporation of NA into replicating DNA. The selection of resistance occurs at different rates for each NA, and is affected by the high mutational rate of HBV and the ability of the drug to suppress viral replication. Some mutations or combinations of mutations may be associated with multidrug resistance, limiting treatment options. In contrast to most other viruses, resistance in HBV is confounded by the overlapping surface gene, the major NA-resistant mutations also altering the surface proteins in most cases, potentially altering virus secretion and neutralization, which may pose a public health threat in the future.

Strategies to eliminate HBV infection

Chronic HBV infection is a major public health concern affecting over 240 million people worldwide. Although suppression of HBV replication is achieved in the majority of patients with currently available newer antivirals, discontinuation of therapy prior to hepatitis B surface antigen loss or seroconversion is associated with relapse of HBV in the majority of cases. Thus, new therapeutic modalities are needed to achieve eradication of the virus from chronically infected patients in the absence of therapy. The basis of HBV persistence includes viral and host factors. Here, we review novel strategies to achieve sustained cure or elimination of HBV. The novel approaches include targeting the viral and or host factors required for viral persistence, and novel immune-based therapies, including therapeutic vaccines.

Seroprevalence of Hepatitis B and C Viruses Among Children in Kilimanjaro Region, Tanzania

BACKGROUND

Data on human immunodeficiency virus (HIV) and hepatitis B virus (HBV) and hepatitis C virus (HCV) coinfection among children in Africa are limited. We evaluated the seroprevalence of both viruses among healthy, HIV-uninfected children and HIV-infected children in the Kilimanjaro region of northern Tanzania.

METHODS

HBV and HCV markers were assessed using serum and plasma samples from HIV-negative children ages 1 month to 18 years, recruited primarily from 2 hospital vaccination clinics; and HIV-infected children 1-16 years of age, enrolled in care and on highly active antiretroviral therapy (HAART). HBV markers included hepatitis B surface antigen (HBsAg), hepatitis B surface antibody, and hepatitis B core antibody (HBcAb). Evidence of any prior HBV infection was defined as a single positive HBsAg or HBcAb result; presumed chronic hepatitis B infection was defined as a single positive HBsAg result. HCV infection was assessed by anti-HCV enzyme-linked immunosorbent assay.

RESULTS

Samples from 547 children were tested. Of 157 children infected with HIV, 9.6% (95% CI: 4.9, 14.2) showed evidence of any HBV infection, compared to 2.1% (95% CI: .6, 3.5) of HIV-negative children. Children with HIV were much more likely to show evidence of HBV infection than children without HIV (odds ratio [OR] = 5.0, P < .0001). Prevalence of presumed chronic HBV infection was 2.9% (95% CI: 1.5, 4.3) overall. Again, prevalence was higher among HIV-infected children (7.0% [95% CI: 3.0, 11.0]) compared to HIV-negative children (1.3% [95% CI: .2, 2.4]; OR = 5.8 [P = .0003]). Of 546 samples tested for anti-HCV antibody, none were positive.

CONCLUSION

HBV seroprevalence is high among children in the Kilimanjaro Region, with a significantly higher prevalence among children who are infected with HIV. Routine screening for HBV is needed among HIV-infected children. Patients with coinfection require closer monitoring of liver transaminases due to potential for hepatic toxicities, and they may need HAART regimens that will target both viruses. Guidelines for the management of coinfected children are urgently needed.

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.

Characterization of treatment-naive HIV/HBV co-infected patients attending ART clinic of a tertiary healthcare centre in eastern India

OBJECTIVE

The study was designed to assess the hepatitis B virus (HBV) and hepatitis C virus (HCV) co-infection scenario among the human immunodeficiency virus (HIV) infected patients attending a tertiary healthcare unit in eastern India. Additionally, clinical and virological characterization of these viruses, prior to antiretroviral therapy (ART) initiation was also done for better understanding of the disease profile.

METHODS

Pool of ART-naive HIV/HBV co-infected and HIV mono-infected patients, participating in two different studies, were included in this study. HBV DNA was detected by nested-PCR amplification followed by HBV genotype determination and HBV reverse transcriptase (RT) region amplification and direct sequencing for detecting drug resistance.

RESULTS

The prevalence of HBsAg (11.3%) was higher compared to anti-HCV (1.9%) among the HIV infected ART-naive patients. Moreover, majority of the HBeAg positive HIV/HBV co-infected patients (87.7%) had HBV DNA ≥20,000 IU/ml with median HBV DNA significantly higher than that of HBeAg negative subjects (5.7 log10 IU/ml vs. 4.2 log10 IU/ml; p<0.0001). Multivariate analysis also showed that HBeAg-positive status was independently associated with higher HBV DNA level (p = <0.001). Notably, 60.9% of the HBeAg negative co-infected subjects had HBV DNA ≥2,000 IU/ml of which 37.0% had HBV DNA ≥20,000 IU/ml. Genotype HBV/D (68.2%) was the predominant genotype followed by HBV/A (24.3%) and HBV/C (7.5%). Anti-HBV drug resistant mutations were detected in two (3.8%) of the ART-naive patients.

CONCLUSION

The prevalence of HIV/HBV co-infection was relatively higher in our study subjects. HBeAg testing might provide clue for early treatment initiation. Furthermore, HBeAg negative patients are also associated with high HBV DNA levels and therefore require appropriate medical attention. Pre-treatment screening for anti-HBV drug resistant mutations is not necessary before ART initiation.

Development of strategies for screening, predicting, and diagnosing intrauterine HBV infection in infants born to HBsAg positive mothers

This study aimed at developing strategies for screening, predicting, and diagnosing intrauterine HBV infection in infants born to HBsAg positive mothers. A total of 1,360 infants born to 1,355 HBsAg positive mothers were followed for 1 year. All newborn infants received active and passive immunization within 24 hr after birth. Maternal and infant blood samples were collected and tested for the status of serum HBsAg, HBeAg, and HBV DNA positivity. The accuracy of infant HBsAg positivity, HBV DNA positivity, HBsAg and HBV DNA double positivity, and HBsAg and/or HBV DNA positivity at birth in the diagnosis of intrauterine HBV infection was evaluated by receiver operating characteristic curve analysis. Of 1,360 infants, 145 tested positive for HBsAg and/or HBV DNA at birth. Twenty-one (1.5%) infants, who were diagnosed with intrauterine HBV infection, showed HBsAg positivity from birth to 7 and 12 months of age. Infant HBsAg positivity at birth had the highest sensitivity in predicting intrauterine HBV infection, while neonatal HBsAg and HBV DNA double positivity had the highest specificity. These findings suggest that infants, who were born to HBsAg positive mothers and were positive for both HBsAg and HBV DNA at birth, may be at a higher risk for intrauterine HBV infection. HBsAg positivity at birth may be a good marker for screening intrauterine HBV infection. Infant HBsAg positivity both at birth and 7 months of age may be used as a diagnostic criterion to simplify diagnostic procedures and improve diagnostic efficiency.

Strategies to increase responsiveness to hepatitis B vaccination in adults with HIV-1

HIV and hepatitis B virus co-infection leads to substantially increased morbidity and mortality compared with either infection alone. Immunisation with hepatitis B virus vaccine is the most effective way to prevent the infection in people with HIV; however, these patients have decreased vaccine responses and a short duration of protection compared with immunocompetent individuals. Control of HIV replication with highly active antiretroviral therapy and increased CD4 cell counts are associated with improved immune responses to hepatitis B vaccination. New vaccination strategies, such as increased vaccine dose, use of the intradermal route, and addition of adjuvants, could improve response rates in adults with HIV.

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.

Hepatitis B escape mutants in Scottish blood donors

Hepatitis B virus (HBV) remains as the viral infection with the highest risk of transmission by transfusion. This risk is associated with window period donations, occult HBV infection (OBI) and the emergence of escape mutants, which render blood donations false negative for hepatitis B surface antigen (HBsAg) serological testing. A retrospective study was conducted to gain insights into the molecular epidemiology of HBV escape mutants in Scottish blood donors. The criterion for selection was HBV positivity either by serology or nucleic acid testing (NAT). HBsAg detection was compared across several commercial immunoassays. The full length S gene from plasma samples was PCR amplified, cloned and expressed in HepG2 cells. Eight samples showed HBsAg discordant results, while 5 OBI samples were found. Four escape mutants, containing missense mutations in the S gene, are described here. These mutations impaired HBsAg detection both from HBV infected plasma samples and from recombinant proteins derived from its infected donors. Phylogenetic analysis showed that most of the mutants were clustered in the genotype D and were closely related to strains from Asia and the Middle East. We report here a proline substitution, outside the major hydrophilic region, that impaired HBsAg detection in vivo and in vitro, warning about the risk for the emergence of vaccine escape mutants with mutations outside the major neutralisation site.

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.

HBV mutations and their clinical significance

PURPOSE

The launch of the vaccine against HBV in 1983 significantly reduced the number of HBV infections in the world. But there still remain a large group of people with chronic hepatitis B who were infected before beginning of vaccination programs or in whom the vaccine was - for various reasons - ineffective. Current therapy of HBV infection based on PEG-IFN α-2a or nucleotide/nucleoside analogues does not guarantee sustained virologic response in the large majority of chronically infected persons. Treatment with some nucleoside analogues is associated with mutations and subsequent selection of resistant strains resulting with therapeutic failure, risk of cross-resistance to other drugs and finally selection of mutants with oncogenic properties.

HBV primary drug resistance in newly diagnosed HIV-HBV-coinfected individuals in Spain

BACKGROUND

The wide use of lamivudine (3TC) as oral therapy for chronic HBV infection has favoured the selection and circulation of 3TC-resistant HBV strains worldwide. Although transmission of 3TC-resistant HBV variants has been reported only sporadically, few studies have been conducted in the HIV population where exposure to 3TC has been greater forming part of antiretroviral therapy (ART) regimens.

METHODS

All individuals positive for serum hepatitis B surface antigen (HBsAg), newly diagnosed with HIV-1 infection, naive to ART and enrolled in the Spanish HIV cohort (CoRIS) since 2004 were identified. The HBV polymerase gene was sequenced and drug resistance mutations were characterized retrospectively in stored frozen plasma specimens.

RESULTS

From 4,419 ART-naive HIV-1-infected individuals, 223 (5.1%) were positive for serum HBsAg. Baseline stored sera were available for 84 patients, of whom 73 could be characterized virologically. This population was mainly represented by men who had sex with men (52.1%), native Spaniards (65.7%) and Latin Americans (16.4%). The mean age was 36 years, mean CD4(+) T-cell count 375 cells/mm(3) and mean plasma HIV RNA 4.5 log(10) copies/ml. The HBV genotype distribution was 64% A, 20% F, 12% D and 4% others. Drug-resistant mutations in the HBV polymerase were found in four (5.5%) patients: two harboured rtL180M, one rtL80V and one rtV173L.

CONCLUSIONS

The rate of primary drug resistance in HBV among newly diagnosed HIV-HBV-coinfected patients in Spain is currently low (5.5%) and restricted to 3TC. Thus, HBV drug resistance testing before prescription of oral antiviral therapy is not warranted, although periodic surveillance might be recommended.

Antiviral drug-associated potential vaccine-escape hepatitis B virus mutants in Turkish patients with chronic hepatitis B

BACKGROUND

The hepatitis B virus (HBV) polymerase (pol) gene completely overlaps with the envelope (S) gene. Mutations in the pol gene of HBV, either from selection of primary or secondary resistance mutations, typically result in changes in the overlapping hepatitis B surface antigen (HBsAg). Recent studies have conferred a new acronym to these HBV pol/S gene overlap mutants: ADAPVEMs, for antiviral drug-associated potential vaccine-escape mutants. The present study aimed to assess the prevalence and pattern of ADAPVEMs in Turkish patients with chronic hepatitis B (CHB).

METHODS

The investigation was conducted between March 2007 and July 2010 and involved a total of 442 patients. These patients were in the following phases of HBV infection: immune tolerant (n=50), immune reactive (n=37), inactive carrier (n=90), HBeAg-negative CHB (n=217), and HBsAg-negative (n=12), or were hemodialysis patients (n=36). One hundred eighty-six patients were receiving nucleos(t)ide analogue (NUC) therapy and 256 patients had treatment-naïve CHB.

RESULTS

Seven types of ADAPVEM were detected in the total CHB patients: rtM204V/sI195M, rtM204I/sW196S, rtM204I/sW196L, rtV173L/sE164D, rtA181T/sW172*, rtA181T/sW172L, and rtA181V/sL173F. The ADAPVEMs were associated with lamivudine, telbivudine, and adefovir. The prevalence of ADAPVEMs in all CHB patients was found to be 10% (46/442). The difference in the prevalence of ADAPVEMs across the different CHB clinical phases was not significant (Pearson Chi-square, p=0.112). The prevalence of ADAPVEMs was 24% (44/186) in those undergoing NUC therapy and 0.7% (2/256) in the treatment-naïve group; this difference was significant (Pearson Chi-square, p=0.00).

CONCLUSIONS

We determined the prevalence and pattern of ADAPVEMs in Turkish patients in the different phases of CHB. Preferred drugs in Turkey, such as lamivudine, have the potential to cause the emergence of ADAPVEMs, with the possibility that these will spread to both individuals immunized with the hepatitis B vaccine and nonimmunized individuals. ADAPVEMs should be monitored in infected and treated patients and their public health risks assessed.

Acute liver failure caused by concurrent autoimmune hepatitis and hepatitis B in a 16-year old girl

A 16 year-old girl was admitted to hospital because of fatigue and somnolence, nausea, epistaxis and jaundice. Physical examination revealed jaundice, an enlarged liver and tenderness of upper right abdomen. Laboratory tests revealed an increased level of acute liver failure, bilirubin, bile acids, GGTP and a decreased prothrombin ratio, with elevated gamma-globulin and IgG levels, and the presence of anti-mitochondrial M2 antibodies and HBV infection markers. The patient was diagnosed with liver failure resulting from chronic hepatitis B with an autoimmune component. The treatment consisted of steroids, azathioprine, vitamin K, low-protein diet and lactulose enemas. After undergoing a molecular test (HBV DNA 3.23 × 10(5) IU/mL and mutations I 204 and I 80), the treatment was modified by adding entecavir. After one month the patient was discharged in good clinical condition, with the recommendation of continued entecavir, prednisone and azathioprine. In subsequent months, no clinical deterioration or abnormal biochemical liver function test results were found, despite the discontinuation of immunosuppressive therapy after 10 mo. The patient continues entecavir therapy.