Lamivudine-resistant HBV strain rtM204V/I in acute hepatitis B

State-of-the-Art Fluorescent Probes: Duplex-Specific Nuclease-Based Strategies for Early Disease Diagnostics

Precision healthcare aims to improve patient health by integrating prevention measures with early disease detection for prompt treatments. For the delivery of preventive healthcare, cutting-edge diagnostics that enable early disease detection must be clinically adopted. Duplex-specific nuclease (DSN) is a useful tool for bioanalysis since it can precisely digest DNA contained in duplexes. DSN is commonly used in biomedical and life science applications, including the construction of cDNA libraries, detection of microRNA, and single-nucleotide polymorphism (SNP) recognition. Herein, following the comprehensive introduction to the field, we highlight the clinical applicability, multi-analyte miRNA, and SNP clinical assays for disease diagnosis through large-cohort studies using DSN-based fluorescent methods. In fluorescent platforms, the signal is produced based on the probe (dyes, TaqMan, or molecular beacon) properties in proportion to the target concentration. We outline the reported fluorescent biosensors for SNP detection in the next section. This review aims to capture current knowledge of the overlapping miRNAs and SNPs' detection that have been widely associated with the pathophysiology of cancer, cardiovascular, neural, and viral diseases. We further highlight the proficiency of DSN-based approaches in complex biological matrices or those constructed on novel nano-architectures. The outlooks on the progress in this field are discussed.

Epidemiological and clinical aspects of hepatitis B virus infection in Italy over the last 50 years

A relevant gradual reduction of both the incidence rate of acute hepatitis B (AHB) and prevalence of chronic hepatitis B has occurred in Italy in the last 50 years, due to substantial epidemiological changes: Improvement in socioeconomic and hygienic conditions, reduction of the family unit, accurate screening of blood donations, abolition of re-usable glass syringes, hepatitis B virus (HBV)-universal vaccination started in 1991, use of effective well tolerated nucleo(t)side analogues able to suppress HBV replication available from 1998, and educational mediatic campaigns against human immunodeficiency virus infection focusing on the prevention of sexual and parenteral transmission of infections. As an example, AHB incidence has gradually decreased from 10/100000 inhabitants in 1985 to 0.21 in 2020. Unfortunately, the coronavirus disease 2019 (COVID-19) pandemic has interrupted the trend towards HBV eradication. In fact, several HBV chronic carriers living in the countryside have become unable to access healthcare facilities for screening, diagnosis, clinical management, and nucleo(t)side analogue therapy in the COVID-19 pandemic, mainly for anxiety of becoming infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), movement restrictions, and reduced gains from job loss. In addition, one-third of healthcare facilities and personnel for HBV patients have been devolved to the COVID-19 assistance.

HBV/HDV Co-Infection: Epidemiological and Clinical Changes, Recent Knowledge and Future Challenges

Several investigations have been published on Hepatitis Delta Virus (HDV) infection in recent years, from which we have drawn the salient data to provide readers with useful information to improve their knowledge on the subject. HDV genotypes 5–8 have been recently imported to Western countries from central Africa, whose clinical relevance deserves further investigation. Ongoing HDV replication has been identified as an independent predictor of progression to cirrhosis and HCC for patients with HDV chronic hepatitis (HDV-CH). Long-term treatments of HDV-CH with standard or pegylated interferon alfa (peg-IFN-α) have all been unsatisfactory, leading to a sustained virological response (SVR) only in 20–30% of patients treated, faced with a poor tolerability and frequent serious adverse reactions; the addition of HBV nucleo(s)tide analogues to peg-IFN- α did not improve the rate of SVR. The improved knowledge of the HDV life cycle has allowed the development of direct acting agents towards key-points of the HDV life cycle, namely bulevirtide, lonafarnib and nucleic acid polymers. Preliminary data have shown that these drugs are more effective than interferon-based therapies, but adverse reactions are also common, which however seem toned down in combination therapy with other antivirals.

Prevalence of hepatitis B virus infection among pregnant women in Jos, Nigeria

Objectives:

The study sought to determine the prevalence and risk factors associated with Hepatitis B surface antigenemia (HBsAg) positivity among pregnant women in Jos, Nigeria.

Methodology:

This was a cross-sectional study carried out among the pregnant population in five healthcare facilities in Jos, between November 1, 2017 and April 30, 2018. Informed consent was obtained, and data on sociodemographic and risk factors for hepatitis B virus (HBV) infection were collected. Hepatitis B viral infection was assessed using the in vitro HBsAg diagnostic rapid kit (Acon Laboratories, USA). Descriptive statistics, Chi-square test, and logistic regression were performed to identify predictors of HBV infection in the study population. All statistical analyses were carried out on STATA version 15.

Results:

Of the 3,238 women enrolled, 7.4% (241/3238) (95% confidence interval [CI] = 6.6% to 8.4%) were HBsAg positive. The absence of HBV vaccination (adjusted odds ratio [AOR] = 2.49; 95% CI = 1.49–4.09; P < 0.001), co-infection with HIV (AOR = 1.90; 95% CI = 1.18–3.08; P = 0.009), and higher parity (AOR = 1.37; 95% CI = 1.04–1.79; P = 0.024) were independently associated with HBV infection in pregnancy.

Conclusions:

The prevalence of HBV infection among pregnant women was high, especially among those without prior vaccination for HBV, those with HIV co-infection and higher parity.

Towards the worldwide eradication of hepatitis B virus infection: A combination of prophylactic and therapeutic factors

Hepatitis B virus (HBV) is still a global health problem, mostly because of the intermediate/high rates of HBV chronic carriers living in most Asian, African and eastern European countries. The universal HBV vaccination of new-borns undertaken in most nations over the last 3 decades and effective HBV antiviral treatments (nucleos(t)ide analogue with high genetic barrier to viral resistance) introduced in the last decade have shown their beneficial effects in inducing a clear reduction of HBV endemicity in the countries where they have been extensively applied. Great hopes are now placed on new antiviral and immunotherapeutic drugs that are now at an advanced stage of study. It is in fact already conceivable that the synergistic use of new drugs targeting more than one HBV-lifecycle steps (covalent closed circular DNA destruction/silencing, HBV entry inhibitors, nucleocapsid assembly modulators targeting viral transcripts) and of some new immunotherapeutic agents might eliminate the intrahepatic covalent closed circular DNA and achieve the eradication of HBV infection. In spite of this, a strong effort should be given to extensive educational and screening programs for the at-risk population and to the implementation of HBV vaccination in developing countries.

Patterns of hepatitis B virus S gene escape mutants and reverse transcriptase mutations among genotype D isolates in Jordan

Background

Hepatitis B virus (HBV) is an important infectious cause of morbidity and mortality in Jordan. HBV genotype D is the most prevalent in the country. Virus escape mutants in the HBV S region is an important public health problem halting preventive efforts. The aim of the current study was to investigate patterns of HBV escape and resistance mutations and to assess domestic transmission of the virus.

Methods

Patients infected with HBV were recruited at Jordan University Hospital (n = 56) and were diagnosed during (1984-2012). A total of 37 partial HBV S sequences were generated using Sanger's method. Mutation analysis was done using the HIV grade HBV drug resistance interpretation online tool and Geno2pheno (HBV) online tools. Domestic transmission of HBV was assessed using maximum likelihood phylogenetic inference with similar GenBank sequences.

Results

Genotyping revealed an exclusive presence of sub-genotype D1. Typical HBV escape mutants were identified in seven patients. These mutations included: L109R, Q129R, M133L, S143L and D144E with overall prevalence of 18.9% (95% CI [9.5-34.2]). Reverse transcriptase (RT) sequence analysis showed mutations in three patients with overall prevalence of 8.1% (95% CI [2.8-21.3]). RT mutations included: V173L, S202I, L180M, M204V and T184A. Transmission cluster analysis revealed a relatively high proportion of infections taking place as a result of domestic spread (29.7%).

Conclusions

Based on our findings, RT mutation analysis appears to be of high value before the initiation of therapy in patients with chronic HBV infection in Jordan. Phylogenetic analyses revealed a considerable proportion of local spread in the country which should be considered in the preventive infection control efforts.

Hepatitis B Virus Adaptation to the CD8+ T Cell Response: Consequences for Host and Pathogen

Chronic viral hepatitis infections are a major public health concern, with an estimated 290 million individuals infected with hepatitis B virus (HBV) globally. This virus has been a passenger in human populations for >30,000 years, and remains highly prevalent in some settings. In order for this endemic pathogen to persist, viral adaptation to host immune responses is pre-requisite. Here, we focus on the interplay between HBV infection and the CD8+ T cell response. We present the evidence that CD8+ T cells play an important role in control of chronic HBV infection and that the selective pressure imposed on HBV through evasion of these immune responses can potentially influence viral diversity, chronicity, and the outcome of infection, and highlight where there are gaps in current knowledge. Understanding the nature and mechanisms of HBV evolution and persistence could shed light on differential disease outcomes, including cirrhosis and hepatocellular carcinoma, and help reach the goal of global HBV elimination by guiding the design of new strategies, including vaccines and therapeutics.

Long-Term Follow-Up of Acute Hepatitis B: New Insights in Its Natural History and Implications for Antiviral Treatment

Acute hepatitis B infection (AHB) is still a common viral acute hepatitis worldwide. As vaccination, antiviral treatment, and immigration are bound to affect the epidemiological landscape of HBV infections, and some of its aspects need to be investigated: (1) the circulation of vaccine escape mutants and of primary drug resistant strains; (2) the change in HBV genotype prevalence; and (3) the clinical implications of AHB and the probability of chronification. The serological, virological, and clinical parameters of 75 patients, acutely infected by HBV, were gathered for a retrospective study. Long-term follow up, either to complete seroconversion or for up to five years, was possible for 44 patients. Sequence analysis of the reverse transcriptase/HBsAg and precore regions was performed to investigate the molecular epidemiology and pathogenesis of recent infections by HBV. Genotype distribution in AHB in Italian patients was radically different from that of chronic infections, with a dramatic increase of extra-European genotypes (A1, F), suggesting that a proportion of AHBs are currently related to imported strains. None of the documented infections occurred in vaccinated individuals, while HBsAg variants (potentially vaccine escape variants) were rare and less prevalent than in chronic infections. No drug resistant strains were observed. Spontaneous viral clearance occurred in all but three cases. Time to viral clearance was inversely proportional to liver damage, but HBsAg titer on day 28 and, better still, HBsAg decay from day 0 to day 28 after admission, were the best predictors of chronification. They are, thus, potentially useful to guide antiviral treatment to prevent chronic evolution.

HBV molecular epidemiology and clinical condition of immigrants living in Italy

INTRODUCTION

We investigated 170 HBsAg-positive immigrants living in Italy for 1-7 years to ascertain whether they may have become infected in the host country.

METHODS

Of 2032 adult immigrants interviewed, 1727 (85%) voluntarily adhered to a screening program for bloodborne or sexually transmitted infections. HBsAg was detected in 170 (9.8%) screened immigrants who completed the diagnostic, clinical and therapeutic process at the nearest clinic of infectious diseases. HBV molecular biology was performed applying a homemade technology. Phylogenetic signal of the datasets was obtained by a likelihood-mapping analysis using TreePuzzle.

RESULTS

Of the 170 HBsAg-positive immigrants, 133 were inactive carriers, 29 had chronic hepatitis and 8 compensated cirrhosis. HBV genotype was identified in 109 of the 113 HBV-DNA-positive immigrants and HBV-genotype-E predominated (68.9%). Of these 109, 6 (5.5%) subjects showed an HBV genotype absent or extremely rare in their native country: HBV-genotype-E in three from Eastern Europe and in one from Sri Lanka, possibly acquired from other immigrants from sub-Saharan countries, HBV-genotype-D1 in one from Burkina Faso and one from Senegal, possibly acquired in Italy.

CONCLUSION

The data suggest that immigrants may acquire HBV infection in Italy and, therefore, HBV vaccination programs should be extended to all immigrants living in Italy.

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.

Relationship between pre-existing resistance mutations and HBV genotype in patients with HBV related liver cirrhosis

AIM

To investigate the relationship between hepatitis B virus (HBV)-related drug resistance mutations and HBV genotype in patients with HBV-related liver cirrhosis (LC).

METHODS

Serum samples were collected from 112 patients with HBV-related LC who did not receive prior anti-viral treatment. HBV reverse transcriptase regions were amplified by PCR, and PCR products were directly sequenced.

RESULTS

Among 112 HBV-related LC patients, 13 (11.61%, 13/112) had lamivudine resistance associated mutations, 15 (13.39%, 15/112) had adefovir resistance associated mutations, and 1 had mutations associated with both lamivudine and adefovir resistance. All of these resistance mutations occurred in patients infected with HBV genotype C, and there was no mutation in patients infected with HBV genotype B.

CONCLUSION

Adefovir/lamivudine resistance associated mutations exist in patients with HBV-related LC, and the mutations are related to HBV genotype. Compared with patients infected with HBV genotype B, those infected with HBV genotype C are prone to resistance mutations.

Molecular diversity in irregular or refugee immigrant patients with HBV-genotype-E infection living in the metropolitan area of Naples

In a recent testing in the metropolitan area of Naples, Italy, on 945 irregular immigrants or refugees, 87 HBsAg chronic carriers were identified, 53 of whom were infected by HBV-genotype E. The aim of the present study was to identify the genetic diversity of HBV-genotype E in these 53 immigrants. The 53 immigrant patients with HBV-genotype-E infection were born in Africa, central or eastern Asia, eastern Europe or Latin America. These patients had been seen for a clinical consultation at one of the four first-level units from January 2012 to 2013. The first dataset contained 53 HBV-S gene isolates plus 128 genotype/subgenotype specific reference sequences downloaded from the National Center for Biotechnology Information. The second dataset, comprising the 53 HBV-S gene isolates, previously classified as HBV-genotype E, was used to perform the time-scaled phylogeny reconstruction using a Bayesian approach. Phylogenetic analysis showed that all 53 HBV-S isolates belonged to HBV-genotype E. Bayes factor analysis showed that the relaxed clock exponential growth model fitted the data significantly better than the other models. The time-scaled Bayesian phylogenetic tree of the second dataset showed that the root of the tree dated back to the year 1990 (95% HPD:1984-2000). Four statistically supported clusters were identified. Cluster A dated back to 2012 (95% HPD:1997-2012); cluster B dated back to 2008 (95% HPD:2001-2015); cluster C to 2006 (95% HPD:1999-2013); cluster D to 2004 (95% HPD:1998-2011). This study disclosed the genetic evolution and phylogenesis in a group of HBV-genotype-E-infected immigrants. J. Med. Virol. 89:1015-1024, 2017. © 2016 Wiley Periodicals, Inc.

Multiple Hepatitis B Virus (HBV) Quasispecies and Immune-Escape Mutations Are Present in HBV Surface Antigen and Reverse Transcriptase of Patients With Acute Hepatitis B

BACKGROUND

This study characterizes and defines the clinical value of hepatitis B virus (HBV) quasispecies with reverse transcriptase and HBV surface antigen (HBsAg) heterogeneity in patients with acute HBV infection.

METHODS

Sixty-two patients with acute HBV infection (44 with genotype D infection and 18 with genotype A infection) were enrolled from 2000 to 2010. Plasma samples obtained at the time of the first examination were analyzed by ultradeep pyrosequencing. The extent of HBsAg amino acid variability was measured by Shannon entropy.

RESULTS

Median alanine aminotransferase and serum HBV DNA levels were 2544 U/L (interquartile range, 1938-3078 U/L) and 5.88 log10 IU/mL (interquartile range, 4.47-7.37 log10 IU/mL), respectively. Although most patients serologically resolved acute HBV infection, only 54.1% developed antibody to HBsAg (anti-HBs). A viral population with ≥1 immune-escape mutation was found in 53.2% of patients (intrapatient prevalence range, 0.16%-100%). Notably, by Shannon entropy, higher genetic variability at HBsAg amino acid positions 130, 133, and 157 significantly correlated with no production of anti-HBs in individuals infected with genotype D (P < .05). Stop codons were detected in 19.3% of patients (intrapatient prevalence range, 1.6%-47.5%) and occurred at 11 HBsAg amino acid positions, including 172 and 182, which are known to increase the oncogenic potential of HBV.Finally, ≥1 drug resistance mutation was detected in 8.1% of patients (intrapatient prevalence range, 0.11%-47.5% for primary mutations and 10.5%-99.9% for compensatory mutations).

CONCLUSIONS

Acute HBV infection is characterized by complex array of viral quasispecies with reduced antigenicity/immunogenicity and enhanced oncogenic potential. These viral variants may induce difficult-to-treat HBV forms; favor HBV reactivation upon iatrogenic immunosuppression, even years after infection; and potentially affect the efficacy of the current HBV vaccination strategy.

Combined Analysis of the Prevalence of Drug-Resistant Hepatitis B Virus in Antiviral Therapy-Experienced Patients in Europe (CAPRE)

BACKGROUND

European guidelines recommend treatment of chronic hepatitis B virus infection (CHB) with the nucleos(t)ide analogs (NAs) entecavir or tenofovir. However, many European CHB patients have been exposed to other NAs, which are associated with therapy failure and resistance. The CAPRE study was performed to gain insight in prevalence and characteristics of NA resistance in Europe.

METHODS

A survey was performed on genotypic resistance testing results acquired during routine monitoring of CHB patients with detectable serum hepatitis B virus DNA in European tertiary referral centers.

RESULTS

Data from 1568 patients were included. The majority (73.8%) were exposed to lamivudine monotherapy. Drug-resistant strains were detected in 52.7%. The most frequently encountered primary mutation was M204V/I (48.7%), followed by A181T/V (3.8%) and N236T (2.6%). In patients exposed to entecavir (n = 102), full resistance was present in 35.3%. Independent risk factors for resistance were age, viral load, and lamivudine exposure (P < .001).

CONCLUSIONS

These findings support resistance testing in cases of apparent NA therapy failure. This survey highlights the impact of exposure to lamivudine and adefovir on development of drug resistance and cross-resistance. Continued use of these NAs needs to be reconsidered at a pan-European level.

Prevalence and types of drug-resistant variants in Chinese patients with acute hepatitis B

The presence of therapy-associated hepatitis B virus (HBV) variants is the main drawback of antiviral therapy for HBV infection. Moreover, drug-resistant variants are more insensitive to a second agent and more therapy-associated mutations will be present. To apply better nucleos(t)ide analogues (NA) and reduce the occurrence of resistance, the prevalence and types of drug-resistant mutations in acute hepatitis B patients were investigated in this study. One hundred three HBV DNA-positive patients with symptomatic acute hepatitis B that were observed from 2011 to 2013 were enrolled. Direct polymerase chain reaction sequencing was used firstly to screen HBV reverse-transcriptase domain to detect HBV mutants. Five lamivudine-resistant variants were identified. Clonal sequencing was performed for 5 resistance-positive samples and 10 other random samples. Interestingly, all detected samples harbored drug-resistant mutations, although with different percentage. Thirteen harbored lamivudine-related alone (five) or together with other NA related mutations (five with adefovir, one with entecavir, and one with telbivudine), and two of them harbored adefovir-related mutations. Also, mutations associated with four currently used NA were all detected, and the frequency is in accordance with the popularity of NA used in clinical practice. These data suggest that drug-resistant variants are present in patients with acute hepatitis B and NA should be applied more carefully for chronic hepatitis B patients developed from acute hepatitis B.

Clinical and virological characteristics associated with severe acute hepatitis B

To identify early predictors of a severe or fulminant course in patients with acute viral hepatitis B (AVH-B). One hundred and thirty-eight patients with symptomatic acute hepatitis B observed from 1999 to 2012 were enrolled. For each patient, the demographics, risk factors for the acquisition of hepatitis B virus (HBV) infection, clinical, biochemical and virological data (HBV DNA, HBV DNA sequences) were recorded and analysed. The HBV mutants in the polymerase region were sought in 110 (87%) patients by direct sequencing, and the rtM204V/I mutations also by an allele-specific PCR. AVH-B was severe in 13 (9.4%) of the 138 patients enrolled, fulminant in 6 (4.3%) and with a normal clinical course in 119. The 19 patients with severe or fulminant AVH-B more frequently than the 119 with a normal course stated intravenous drug use (63.2% versus 36.1%, p 0.04) and were HBV-DNA negative (31.6% versus 11.8%, p 0.03) and anti-hepatitis C virus (HCV) positive (57.9% versus 19.3%, p 0.0008); the prevalences of different HBV genotypes and of the rtM204V/I mutant were similar in these three forms of AVH-B. A multivariate logistic regression analysis identified a pre-existing HCV chronic infection as the only factor independently associated with a severe or fulminant clinical course of AVH-B (OR 4.89, 95% CI 1.5-15.94, p 0.01). A pre-existing HCV chronic infection was identified as the only factor independently associated with a severe clinical presentation of acute hepatitis B, an association most probably due to the combination of the liver lesions caused by acute hepatitis B and the pre-existing histological abnormalities related to HCV chronic infection.

Recommendations for the management of acute hepatitis B: position paper of the Italian Society for the Study of Infectious and Tropical Diseases (SIMIT)

PURPOSE

To develop recommendations for the management of acute hepatitis B by the Italian Society for the Study of Infectious and Tropical Diseases.

METHODS

Development of the recommendations divided into three levels of evidence according to the GRADE system: A (high), B (medium) and C (low experts opinion), together with three recommendation levels: 1 (strong), 2 (medium), 3 (weak).

RESULTS

The treatment with antivirals is in selected cases the mainstay of management of severe acute hepatitis, and should be started as a matter of urgency in order to prevent death.

CONCLUSIONS

These recommendations are meant to provide the rationale and practical indications for the management of acute hepatitis B (AHB).

Molecular epidemiology of hepatitis B virus genotypes circulating in acute hepatitis B patients in the Campania region

Fifty-three HBV-DNA-positive patients with symptomatic acute hepatitis B were enrolled from 1999 to 2010 to evaluate molecular and phylogenetic changes in HBV in southern Italy. HBV polymerase region was evaluated by direct sequencing in plasma samples obtained at first observation. Different data sets were aligned and a phylogenetic tree was inferred using PhyML program. Statistical robustness was confirmed with a bootstrap analysis. A Bayesian Markov chain Monte Carlo method and a Bayesian skyline plot were used to estimate the evolution of our samples. The dN/dS rate (ω) was estimated by the maximum likelihood approach to investigate the presence of codons under positive selection. The MacClade program was used to test viral gene out/in flow only among HBV-D3 subgenotype patients with different risk factors. Of the 53 patients, 83% were born in Italy and 17% were foreigners. HBV genotype D was prevalent (64.1%), followed by genotype A (26.4%), E (3.8%), and F (5.7%). The prevalent subgenotype was D3 (70.6%). The Bayesian tree of the 24 D3 subgenotypes showed two main clades both dated 1994; 40% of viral gene flow observed was from intravenous drugs users and heterosexual patients. Phylogenetic analysis of HBV isolates showed that HBV-D3 remains the prevalent genotype, but also subgenotype A2 has become frequent in southern Italy. This may be of clinical relevance in years to come, since patients with HBV-genotype-A chronic infection less frequently than those with genotype D develop HBeAg-negative chronic hepatitis and respond more frequently to alfa-interferon treatment.

Vertical transmission of hepatitis B virus: challenges and solutions

More than 240 million people worldwide are chronically infected with hepatitis B virus (HBV). Mother-to-child transmission remains the most important mechanism of infection in countries with a high prevalence of HBV. Universal screening of all pregnant women, at-birth prophylaxis with specific anti-HBV immune globulin, as well as HBV vaccination for newborns of infected mothers are effective in reducing the risk of vertical transmission. However, in cases of a high viral load and hepatitis B e antigen positivity, there is a residual risk of HBV transmission to the newborn despite prophylaxis. This review focuses on the above-indicated strategies and on the efficacy and safety of antiviral drugs administered during the third trimester of pregnancy.

Evaluation of HBV DNA decay kinetics in patients containing both rtM204V/I mutant and wild-type HBV subpopulations during tenofovir DF (TDF) monotherapy or combination therapy with emtricitabine (FTC)/TDF

Tenofovir disoproxil fumarate (TDF) is recommended as treatment for chronic hepatitis B patients harboring lamivudine-associated resistance mutations (LAM-R, rtM204V/I ± rtL180M). This study evaluated the clinical response of rtM204V and rtM204I subpopulations to TDF by comparing their early viral load decay kinetics to wild-type (WT) subpopulations in chronic hepatitis B patients harboring rtM204V/I prior to initiating TDF or emtricitabine (FTC)/TDF therapy. Allele-specific PCR assays capable of detecting rtM204V or rtM204I subpopulations as low as 0.5% were developed and used to assess patient samples from a Phase 3b study evaluating TDF and FTC/TDF treatment in LAM-R patients. Baseline samples (n = 280) were quantified for rtM204V/I subpopulations and rtM204V or rtM204I subpopulations were detected in 269/273 (98.5%) baseline samples with a range of 0.7% to >95%. On-treatment analyses were conducted for seventeen patients (TDF, n = 8; FTC/TDF, n = 9) that harbored baseline WT and either rtM204V or rtM204I (no rtM204V/I mixtures) and HBV DNA ≥1,000 copies/ml at/after week 4. The median change in HBV DNA through week 12 for WT and rtM204V/I subpopulations was similar, -2.64 and -3.30 log10  copies/ml, respectively, with no significant difference between TDF and FTC/TDF treatment. In conclusion, rtM204V/I subpopulations demonstrate similar early HBV DNA decline kinetics to WT subpopulations during treatment with either TDF or FTC/TDF. These results demonstrate that TDF is similarly active against both WT and rtM204V/I subpopulations in vivo.

Prevention of mother-to-child transmission of hepatitis B virus and hepatitis C virus

About 240 million people worldwide are chronically infected with hepatitis B virus (HBV). Vertical transmission is the most important mechanism of infection persistence in endemic areas. About 150 million people worldwide are chronically infected with hepatitis C virus (HCV). Mother-to-child transmission of HCV, which occurs in 3-10% of cases, is the leading route of infection in childhood. This review focuses on strategies to reduce the vertical transmission of HBV and HCV. The at-birth prophylaxis of newborns of HBV-infected mothers with specific immunoglobulin and vaccine plus administration of antivirals (tenofovir or telbivudine) in the third trimester of pregnancy (in case of high maternal viral load) greatly reduces the risk of transmission. In contrast, currently there is no drug able to reduce the vertical transmission of HCV infection. We discuss the possibility of reducing mother-to-child HCV transmission using newly available antivirals or antivirals in the pipeline for the treatment of hepatitis C.

Profile of hepatitis B virus resistance mutations against nucleoside/nucleotide analogue treatment in Chinese patients with chronic hepatitis B

Aim

Antiviral drug-resistant HBV mutants are complex and currently partly understood. This study was performed to analyze the profile of hepatitis B virus (HBV) resistance mutations against nucleos(t)ide analogues (NAs) in patients with chronic hepatitis B (CHB).

Methods

This was a population-based cross-sectional study. Serum samples of 179 patients with virological breakthrough undergoing different NAs treatment were obtained between January 2008 and December 2012. The HBV reverse transcriptase region was sequenced and the following NAs-resistant changes including rtL80, rtI169, rtV173, rtL180, rtA181, rtT184, rtA194, rtS202, rtM204, rtN236 and rtM250 were analyzed.

Results

In this cohort, 21.2% (38/179) were genotypes B and 78.8% (141/179) were genotypes C; and 89.4% (160/179) of them detected NAs-resistant mutations. The prevalence of HBV mutations at rtM204 was 93.0% (106/114) in patients with lamivudine (LAM) or telbivudine (LdT)-based therapies, and that of rtN236 mutations was 76.1% (35/46) in patients with adefovir dipivoxil (ADV)-based therapies. Among LAM/LdT based therapies, HBV rtM204I was significantly associated with HBV rtL80I/V mutations [rtM204I+rtL80I/V (50.0%, 32/64) vs. rtM204V+rtL80I/V (27.3%,9/33), P=0.032]; while the HBV rtM204V mutations was significantly associated with HBV rtL180M mutations [rtM204V+rtL180M (100%, 33/33) vs. rtM204I+rtL180M (60.9%, 39/64), P<0.001]. Additionally, HBV rtA181 mutations were observed in 19.3% (22/114) of patients with LAM/LdT-based therapy and 23.9% (11/46) of patients with ADV-based therapy.

Conclusions

Majority of virological breakthrough is associated with NAs-resistant HBV, and the mutation patterns of NAs-resistant HBV are complicated in real clinical practice.