Characterization of hepatitis B virus reverse transcriptase sequences in Chinese treatment naive patients

The central nervous system is a potential reservoir and possible origin of drug resistance in hepatitis B infection

Background

The significance of hepatitis B virus (HBV) in cerebrospinal fluid (CSF) is unclear.

Methods

Synchronous serum and CSF samples were collected from 13 patients. HBV DNA, full-length genome, quasispecies, phylogenetic tree, compartmentalization and mutation of the reverse transcriptase (RT) region were performed based on PCR and sequencing methods.

Results

HBV DNA was detected in the CSF of 3 antiviral-naïve individuals and 1 individual after successful antiviral therapy. Complete full-length HBV genomes were isolated from the CSF of 5 individuals, including 2 with undetectable serum HBV DNA. Ten individuals exhibited distinct CSF-serum quasispecies, 8 harbored independent CSF-serum genetic compartmentalization and phylogenetic trees, and 5 lamivudine/entecavir-associated resistance mutations only in the CSF. The frequencies of rtL180M and rtM204I/V mutations in both serum and CSF were higher in HIV-HBV-coinfected individuals than in the HBV-monoinfected ones (serum: rtL180M: 3.9% vs. 0, P = 0.004; rtM204I/V: 21.3% vs. 0, P < 0.001; CSF: rtL180M: 7.6% vs. 0, P = 0.026; rtM204I/V 7.6% vs. 1.6%, P = 0.097).

Conclusion

CSF is a potential HBV reservoir, and HBV in CSF harbors distinct evolution and mutation characteristics from those in serum. HIV infection increases the possibility of HBV rtL180M and rtM204I/V mutations in both serum and CSF.

A Recent Prevalence of Hepatitis B Virus (HBV) Genotypes and Subtypes in Asia: A Systematic Review and Meta-Analysis

Background and Aim: Despite introducing the hepatitis B virus (HBV) vaccine, the incidence of the Hepatitis B virus globally is still a major health concern. This systematic review and meta-analysis were conducted to provide detailed information on the prevalence of HBV genotypes and subtypes in circulation in Asia. Methods: A systematic search for articles describing the prevalence of HBV genotypes and subtypes in Asia was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Results: Our search returned 207 eligible articles involving 49,279 genotypes and 7457 subtypes representing 28 Asian countries. A meta-analysis was performed on our eligible studies using the Random effect Model. The pooled prevalence of HBV genotypes showed that genotype C (30.9%) (95% CI, 27.5–34.5%; I2 = 97.57%; p < 0.001) was the most common HBV genotype in Asia, followed by genotype B (17.8%) (95% CI, 15.5–20.4%; I2 = 97.26%; p < 0.001) and genotype D (15.4%) (95% CI, 11.8–19.8%). Vietnam had the highest prevalence of genotype B, Lebanon had the highest prevalence of genotypes C, and Jordan had the highest prevalence of genotype D. There was variation in genotypic prevalence with respect to the target genes for HBV genotyping. Reverse dot blot hybridization had the highest estimate of genotypes B and C. HBV subtype C2 (40.0%) (95% CI, 33.3–47.0) is the most prevalent HBV subtype. Conclusion: Evidence from this study reveals that HBV genotypes C and B are the most dominant HBV genotypes in Asia, and HBV subtype C2 is more endemic in Asia.

Prevalence of Potential Resistance Related Variants Among Chinese Chronic Hepatitis B Patients Not Receiving Nucleos(T)ide Analogues

Background and Aims

Potential drug resistance (DR) related variants in the hepatitis B virus (HBV) reverse transcriptase (RT) region may be associated with the effectiveness of antiviral drugs and disease progression. The aim of this study was to investigate the prevalence and clinical characteristics of potential DR-related variants in Chinese CHB patients not receiving nucleos(t)ide analogues (NAs).

Patients and Methods

Two hundred and six untreated CHB patients from Huzhou Central Hospital in eastern China were recruited for this study. The serum DNA was extracted and the HBV RT region was amplified using nest polymerase chain reaction (nest-PCR). The 42 potential DR-related variants were analyzed by direct sequencing.

Results

Among these CHB patients, HBV genotype B and genotype C were identified in 121 (58.7%) and 85 (41.3%) patients, respectively. Potential DR-related variants were detected in 42.7% (88/206) of patients. Primary and secondary DR variants were found in 7.3% (15/206) of patients, including rtL80I/V, rtI169T, rtV173L rtL180M, rtA181T/V, rtM204I/V, and rtN236T. The variants at rt53, rt82, rt221, rt233, rt237, and rt256 were specific for genotype B, and those at rt38, rt84, rt126, rt139, rt153, rt191, rt214, rt238, and rt242 were specific for genotype C. Moreover, the variation frequency in the A-B interdomain (3.96%) was significantly higher than that in the functional domains (1.17%) and non-A-B interdomains (1.11%). Multivariate logistic regression analysis showed that lower HBV-DNA load (<10⁶ IU/mL) was an independent factor associated with potential DR-related variants in untreated CHB patients (P <0.05).

Conclusion

Potential DR-related variants were frequent and complex in untreated Chinese CHB patients. Furthermore, the variants may contribute to decreased serum HBV-DNA loads. However, the effects of potential DR-related variants on the antiviral therapy and liver disease progression require further study.

Hepatitis B virus reverse transcriptase polymorphisms between treated and treatment-naïve chronically infected patients

The aim of this study was investigation of variation(s) in the Hepatitis B virus (HBV) reverse transcriptase domain. 120 patients with chronic HBV infection recruited. 104 patients were received nucleos(t)ide analogs treatments. DNA extractions were done from plasma samples. Direct sequencing and alignment of Polymerase Chain Reaction products were applied for further analysis. HBV genotypes determined by NCBI's Genotyping Tool. Polymorphism(s) were detected by using DnaSP software. Of 120 samples, 98 were sequenced. All of products were HBV genotype D. 13/98 (13.27%) of patients had M539I/V substitutions corresponding to YMDD motif. FLLAQ to FLMAQ was observed among 22/98 (22.98) patients. Two substitutions N459Y and L515M were significantly correlated (R2 = 0.486 and R2 = 0.941 respectively) with FLLAQ motif variation. Mutation ratio among treatment-received patients to treatment-naïve patients was 0.2-0.6. Drug resistance conferring substitutions (DRCSs) were rtL180M (22/98), rtA194V (11/98), rtM204V (1/98), and rtM204I (11/98). Furthermore, six variants were observed among all patients. Appearance of DRCSs in HBV polymerase is a major obstacle to the virus treatments. In the present study, it was shown that DRCSs are more prevalent among treated patients. Therefore, replacement of current anti-viral regimen with novel anti-HBV drugs is warranted in the future.

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.

Characteristics of HBV infection in 705 HIV-infected patients under lamivudine-based antiretroviral treatment from three regions in China

Purpose

This study aimed to investigate the HIV and hepatitis B virus (HBV) co-infection in three HIV high endemic areas with different modes of HIV transmission and explore the HBV nucleos(t)ide analogue resistance (NUCr) substitutions in this cohort receiving antiretroviral therapy (ART).

Patients and methods

The enrolled 705 HIV-infected patients were from three different regions in China and received lamivudine-based ART for at least 1 year. After screening for hepatitis B surface antigen (HBsAg), the hepatitis B e antigen (HBeAg), and antibody against hepatitis B core antigen (anti-HBc and anti-HBc IgM), HBV DNA in plasma of patients positive for HBsAg was tested. The reverse transcriptase (RT) sequences of HBV were analyzed by direct sequencing.

Results

The overall HBsAg-positive rate was 7.1% (50/705) (Guangxi [25/170, 14.7%], Xinjiang [13/257, 5.1%], and Henan [12/278, 4.3%]). The age, transmission route, and ethnic status were found to be associated with HIV/HBV co-infection. We obtained 23 HBV RT sequences belonging to genotypes B (9/23, 39.1%), C (13/23, 56.5%), and D (1/23, 4.4%). About 65.2% (15/23) of RT sequences harbored NUCr substitutions, all of which had combination substitution patterns. Patients with HBV NUCr had significantly higher HBV DNA level and ratio of HBeAg-positive than those without NUCr. None of the patients was found to have both lamivudine-resistant HBV and HIV.

Conclusion

Our results suggested that HBsAg-positive rate in the studied patients was similar to that of the general population in each of the studied regions, where the age, transmission route, and ethnic status might also play roles in HIV/HBV co-infection. The HBV combination NUCr substitutions were common in co-infected patients under ART. Monitoring of HBV infection and NUCr substitutions in HIV-infected patients would help in providing better clinical decisions and management, thus lowering patients’ risks to develop end-stage liver diseases.

Naturally occurring hepatitis B virus reverse transcriptase mutations related to potential antiviral drug resistance and liver disease progression

The annual number of deaths caused by hepatitis B virus (HBV)-related disease, including cirrhosis and hepatocellular carcinoma (HCC), is estimated as 887000. The reported prevalence of HBV reverse transcriptase (RT) mutation prior to treatment is varied and the impact of preexisting mutations on the treatment of naïve patients remains controversial, and primarily depends on geographic factors, HBV genotypes, HBeAg serostatus, HBV viral loads, disease progression, intergenotypic recombination and co-infection with HIV. Different sensitivity of detection methodology used could also affect their prevalence results. Several genotype-dependent HBV RT positions that can affect the emergence of drug resistance have also been reported. Eight mutations in RT (rtL80I, rtD134N, rtN139K/T/H, rtY141F, rtM204I/V, rtF221Y, rtI224V, and rtM309K) are significantly associated with HCC progression. HBeAg-negative status, low viral load, and genotype C infection are significantly related to a higher frequency and prevalence of preexisting RT mutations. Preexisting mutations are most frequently found in the A-B interdomain of RT which overlaps with the HBsAg “a” determinant region, mutations of which can lead to simultaneous viral immune escape. In conclusion, the presence of baseline RT mutations can affect drug treatment outcomes and disease progression in HBV-infected populations via modulation of viral fitness and host-immune responses.

An Overview of Hepatitis B Virus Surface Antigen Secretion Inhibitors

Current anti-hepatitis B virus (HBV) regimen do not meet ideal result due to emerging resistance strains, cytotoxicity, and unfavorable adverse effects. In chronic HBV infection, high rates of sub-viral particles (SVPs) bearing HBV surface antigen (HBsAg) is a major obstacle regarding to raise effective immune responses and subsequently virus clearance. Development of potent HBsAg secretion inhibitors would provide a better insight into HBV immunopathogenesis and therapy. Investigating new non-toxic HBsAg secretion inhibitors targeting either viral or cellular factors could restore the immune response to remove virally infected hepatocytes after inhibiting SVPs. In this study, we overview several classes of HBV inhibitors with focus on their limitations and advantages over anti-HBsAg secretion potential.

HBV Drug Resistance Substitutions Existed before the Clinical Approval of Nucleos(t)ide Analogues: A Bioinformatic Analysis by GenBank Data Mining

Naturally occurring nucleos(t)ide analogue resistance (NUCr) substitution frequencies in the reverse transcriptase (RT) of the hepatitis B virus (HBV) were studied extensively after the clinical approval of nucleos(t)ide analogues (NUCs; year of approval 1998). We aimed to study NUCr substitutions in HBV RT sequences obtained before 1998 and better understand the evolution of RT sequences without NUC pressures. Our strategy was to retrieve HBV sequences from GenBank deposited before 1998. The initial search used the keywords "hepatitis B virus" or "HBV" and 1139 sequences were found. Data analyses included information extraction: sequence quality control and amino acid substitution analysis on 8 primary NUCr and 3 secondary substitution codons. Three hundred and ninety-four RT-containing sequences of 8 genotypes from 25 countries in 4 continents were selected. Twenty-seven (6.9%) sequences were found to harbor substitutions at NUCr-related codons. Secondary substitutions (rtL80V and rtV173G/A/L) occurred more frequently than primary NUCr substitutions (rtI169L; rtA181G; T184A/S; rtS202T/R; rtM204L and rtM250K). Typical amino acid substitutions associated with NUCr were of rtL80V, rtV173L and rtT184A/S. We confirm the presence of naturally occurring typical HBV NUCr substitutions with very low frequencies, and secondary substitutions are more likely to occur than primary NUCr substitutions without the selective pressure of NUCs.

Compartmental HBV evolution and replication in liver and extrahepatic sites after nucleos/tide analogue therapy in chronic hepatitis B carriers

BACKGROUND

Hepatitis B virus (HBV) variants are associated with nucleos/tide analogue (NA) response and liver disease but it is unknown whether NA influences extrahepatic HBV persistence.

OBJECTIVES

To investigate HBV replication and genetic evolution in hepatic and extrahepatic sites of chronic hepatitis B (CHB) before and after NA therapy.

STUDY DESIGN

A total of 13 paired plasma, peripheral blood mononuclear cells (PBMC), were collected from chronic HBV carriers at baseline and after a median 53 weeks NA therapy as well as liver biopsy (N=7 baseline, N=5 follow-up). HBV covalently closed circular DNA (cccDNA) and messenger (m) RNA in liver and PBMC were analyzed. HBV polymerase (P)/surface (S), basal core promoter (BCP)/pre-core (PC)/C gene clonal sequencing was done in plasma, peripheral blood mononuclear cells (PBMC), and liver.

RESULTS

Compare to baseline, at ∼53 weeks follow-up, there was no significant change in HBV cccDNA levels in liver (0.2-0.08 copies/hepatocyte, p>0.05) or in PBMC 0.003-0.02 copies/PBMC, p>0.05), and HBV mRNA remained detectable in both sites. At baseline, BCP variants were higher in PBMC vs. liver and plasma. After therapy, drug resistant (DR) and immune escape (IE) variants increased in liver but IE and PC variants were more frequent in PBMC. HBV P/S diversity was significantly higher in PBMC compared to plasma.

CONCLUSION

Continuous HBV replication occurs in liver and PBMC and shows compartmentalized evolution under selective pressure of potent NA therapy.

Molecular epidemiology of hepatitis B virus isolated from Bangladesh

BACKGROUND

Hepatitis B virus (HBV) is highly contagious and causes liver diseases. Globally more than 350 million people are chronically infected and among them above 80 % are from developing countries like Bangladesh. Resistance to existing drugs and vaccines are common phenomenon due to mutations in HBsAg 'a' determinant. Due to lack of data about mutations and subtypes of HBV in Bangladesh, this study strongly demands to be documented. Here, we determined the genotypes and subtypes of HBV prevalent in Bangladesh, and their genomic mutations associated with vaccine and drug resistance.

RESULTS

Among 385 samples, a total of 54 (14 %) were found HBV positive, of which 19 samples were subjected to be sequenced. After bioinformatic analysis, we found Genotype D as predominant genotype (73.7 %) with subtypes ayw3 (64.3 %) and ayw2 (35.7 %), followed by genotype A with subtype adw2 (15.8 %), and then genotype C with subtype adr (10.5 %). A significant number of mutations (Thr118Val, Thr125Met, Thr126Ile, Pro127Thr, Ala128Val, Thr131Asn/Ser, Thr/Ser143Leu/Met) were found in 'a' determinant region which may admit resistance to the available vaccines and failure of HBsAg detection.

CONCLUSIONS

This comprehensive study have clinical importance like disease diagnosis and treatment. It emphasizes HBV infected patients to do molecular diagnosis for choice of anti-viral drugs and effectiveness of vaccines for proper treatment.

Microarray-based genotyping and detection of drug-resistant HBV mutations from 620 Chinese patients with chronic HBV infection

Background

Research has shown that hepatitis B virus (HBV) genotypes are closely linked to the clinical manifestations, treatment, and prognosis of the disease.

Objective

To study the association between genotype and drug-resistant HBV mutations in 620 Chinese patients with chronic HBV infection.

Methods

HBV DNA levels were determined using real-time quantitative PCR in plasma samples. Microarrays were performed for the simultaneous detection of HBV genotypes (HBV/B, C, and D) and drug-resistance-related hotspot mutations. A portion of the samples analyzed using microarrays was selected randomly and the data were confirmed using direct DNA sequencing.

Results

Most samples were genotype C (471/620; 76.0%), followed by genotype B (149/620; 24.0%). Among the 620 patient samples, 17 (2.7%) had nucleotide analogs (NA) resistance-related mutations. Of these, nine and eight patients carried lamivudine (LAM)-/telbivudine (LdT)-resistance mutations (rtL180M, rtM204I/V) and adefovir (ADV)-resistance mutations (rtA181T/V, rtN236T), respectively. No patients had both lamivudine (LAM)- and either adefovir (ADV) or entecavir (ETV) resistance mutations. Additionally, out of the 620 patient samples, 64.0% (397/620) were also detected with the precore stop-codon mutation (G1896A) by microarray assay.

Conclusion

The results of the current study revealed that the prevalence of nucleotide analogs (NA)-resistance in Chinese hospitalized HBV-positive patients was so low that intensive nucleotide analogs (NA)-resistance testing before nucleotide analog (NA) treatment might not be required. In addition, the present study suggests that chronic HBV patients with genotype C were infected with fitter viruses and had an increased prevalence of nucleotide analogs (NA)-resistance mutations compared to genotype B virus.

Nucleotide analogue-resistant mutations in hepatitis B viral genomes found in hepatitis B patients

Chronic hepatitis B (CHB) is treated with nucleos(t)ide analogues (NAs). The reverse transcriptase (RT) region in the hepatitis B virus (HBV) genome mutates to resist NA treatment, yet the RT mutations have not been well characterized. Furthermore, the HBV genotype might influence RT sequence evolution, NA resistance (NAr) mutation patterns and drug resistance development. We examined 42 NAr mutation sites in 169 untreated and 131 NA-treated CHB patient samples. Patients were identified with HBV-B and HBV-C genotype infections, with a higher prevalence and mutation frequency of HBV-C than HBV-B. Seventeen reported NAr mutation sites and 13 novel mutations were detected. NAr-related mutation prevalence was significantly higher in NA-treated versus untreated patients. Primary antiviral-resistant mutants only existed in NA-treated patients. Sequencing data revealed seven HBV-C-specific mutations and three HBV-B-specific mutations. In conclusion, NA treatment and HBV genotype might constitute the selection basis and promote NA-resistant HBV strain evolution under antiviral therapy.

Mutations in HBV DNA polymerase associated with nucleos(t)ide resistance are rare in treatment-naive patients

BACKGROUND & AIMS

Prior studies have detected hepatitis B virus (HBV) DNA polymerase mutations in treatment-naive patients. However, most of these studies used either direct polymerase chain reaction sequencing, which detects these mutations with low levels of sensitivity, or patient cohorts that were not well-characterized. We investigated the prevalence of HBV mutations in DNA polymerase by using a line probe assay.

METHODS

In a prospective, cross-sectional study, we enrolled 198 treatment-naive patients with chronic hepatitis B (52.5% male; mean age, 41 years) from February 2009 to May 2011 from 3 gastroenterology and liver clinics in Northern California. Exclusion criteria included infection with hepatitis C or D viruses or human immunodeficiency virus. All patients completed a questionnaire (to determine demographics, history of liver disease, prior treatments, family medical history, drug and alcohol use, and environmental risk factors for hepatitis) that was administered by a research coordinator; mutations in HBV DNA polymerase were detected by using the INNO-LiPA HBV DR v.3 assay.

RESULTS

Most patients were Vietnamese (48.5%) or Chinese (36.4%) and were infected with HBV genotypes B (67.5%) or C (24.2%). Mutations in HBV DNA polymerase were found in 2 patients (1%), rtI233V (n = 1) and rtM250M/L (n = 1).

CONCLUSIONS

In a multicenter prospective study of treatment-naive patients with chronic hepatitis B, we detected mutations in HBV DNA polymerase in only 1%. Because of the low prevalence of these mutations and the uncertain clinical significance of such quasispecies, routine HBV DNA polymerase mutation analysis cannot be recommended before initiation of antiviral therapy for treatment-naive patients with chronic hepatitis B. The analysis requires further molecular and clinical studies.

Investigation into drug-resistant mutations of HBV from 845 nucleoside/nucleotide analogue-naive Chinese patients with chronic HBV infection

BACKGROUND

This study aimed to clarify the clinical significance of drug-resistant HBV in nucleoside/nucleotide analogue (NA)-naive Chinese patients with chronic HBV infection in real clinical practice.

METHODS

A total of 845 NA-naive patients who were admitted to Beijing 302 Hospital between July 2007 and March 2012 were included in the study. HBV drug-resistant mutations were examined by direct sequencing of the viral reverse transcriptase gene and verified by clonal sequencing. Phenotypic analysis of viral replication capacity and drug susceptibility were performed by measuring viral replicative intermediate level in 1.1-mer mutant or wild-type HBV amplicon-transfected HepG2 cells in absence or presence of serially diluted drugs.

RESULTS

Drug-resistant mutations were detected in 2.01% (17/845) of the patients by direct sequencing, including 15 with lamivudine-resistant mutations (rtM204V, rtM204I), one with adefovir-resistant mutation (rtA181V), and one with both lamivudine- and adefovir-resistant mutations (rtA181V, rtM204I). Clonal sequencing identified 13 drug-resistant HBV strains: rtL80I+M204I, rtL80I+M204V, rtL180M+M204I, rtL180M+M204V, rtM204I, rtM204V, rtL80I+L180M+M204I, rtL80I+L180M+M204V, rtA181V, rtA181V+M204I, rtA181T+N236T, rtA181V+N236T and rtN236T. Phenotypic analysis showed that two pre-existing lamivudine-resistant strains (rtL80I+M204I, rtL180M+M204V) had >1,000-fold resistance to lamivudine, and one pre-existing adefovir-resistant strain (rtA181V+N236T) had 15.4-fold resistance to adefovir compared with the wild-type strain. A follow-up study showed that the presence of pre-existing rtM204I strain in one patient increased from 20% at baseline to 85% after 13 months of entecavir treatment with corresponding recession of wild-type strain in the viral pool.

CONCLUSIONS

The incidence of drug-resistant HBV mutations was low in NA-naive Chinese HBV-infected patients. Pre-existing mutants had similar resistance characteristics to those from NA refractory patients.

Amino acid polymorphism in the reverse transcriptase region of hepatitis B virus and the relationship with nucleos(t)ide analogues treatment for preventing mother-to-infant transmission

A high maternal serum hepatitis B virus (HBV) DNA level is associated with vaccine failure. The administration of nucleos(t)ide analogues (NAs) in pregnancy for decreasing serum HBV is regarded as an effective and safe method to reduce HBV perinatal transmission. However, the effect of NAs treatment is closely related to amino acid polymorphisms in the HBV reverse transcriptase (RT) region. The full-length RT coding region of 334 HBV isolates from untreated Chinese women of childbearing age with persistent HBV infection were sequenced and amino acid polymorphic analysis was performed to evaluate its impact on NAs treatment for decreasing HBV perinatal transmission. Of the 334 isolates, 36 (10.8%) harbored NAs resistance (NAr) mutations which were mainly putative drug mutations related to lamivudine. The primary drug mutation rtA181T/V was detected in three HBeAg-negative women with an HBV DNA level of <4 log IU/ml. These NAr mutations were rarely detected in women with an HBV DNA level of ≥7 log IU/ml (P = 0.014) or in women younger than 35 years (P = 0.001). The NAr mutation rate among young women (<35 years) who had a high HBV DNA level (≥7 log IU/ml) was significantly lower than in women who had lower HBV DNA levels (<7 log IU/ml) or who were older (≥35 years; P = 0.017). These results suggest that younger women with a high HBV DNA level harbor fewer NAr mutations and that this population may respond to NAs treatment for the prevention of mother-to-infant transmission.

An initial assessment of correlations between host- and virus-related factors affecting analogues antiviral therapy in HBV chronically infected patients

BACKGROUND

Success in treating hepatitis B virus (HBV) infection with nucleoside analogues drugs is limited by the emergence of drug-resistant viral strains upon prolonged therapy. In addition to mutation patterns in the viral polymerase gene, host factors are assumed to contribute to failure of treatment in chronic HBV infections. The aim of this study was to analyze the correlation between efficacy of antiviral therapy and the prevalence of HBV pretreatment drug-resistant variants. We also analyzed the role of heterogeneity in the promoter region of the IL-10 on the HBV pol/s gene polymorphisms and efficacy of analogues-driven therapy.

MATERIAL AND METHODS

HBV DNA was extracted from 54 serum samples from chronic hepatitis B (CHB) patients. Drug-resistance mutations were analyzed using MALDI-TOF mass spectrometry technology (MALDI-TOF MS) and Multi-temperature single-strand conformation polymorphism (MSSCP). IL-10 gene promoter region polymorphisms at positions -1082, -819, and -592 were determined in allele-specific PCR reactions (AS-PCR).

RESULTS

Drug-resistance mutations were detected in 74% of naïve and 93% of experienced patients, but the effect of pre-existence of drug-resistant HBV variants on antiviral therapy was not statistically significant (p=0.86). The role of polymorphisms at positions -1082 (p=0.88), -819 (p=0.26), and -592 (p=0.26) of IL-10 promoter region polymorphisms was excluded from the response-predicting factors. The main host factors predicting successful response to antiviral therapy were female sex (p=0.007) and young age (p=0.013).

CONCLUSIONS

The presence of drug-resistant HBV variants in baseline is not a viral predictor of good response to nucleoside/nucleotide analogues therapy. Only low HBV viral load predicted positive response to antiviral therapy. The ideal candidate for antiviral therapy is an immunocompetent, young female with low HBV viral load and elevated ALT activity.

Application of deep sequence technology in hepatology

Deep sequencing technologies are currently cutting edge, and are opening fascinating opportunities in biomedicine, producing over 100-times more data compared to the conventional capillary sequencers based on the Sanger method. Next-generation sequencing (NGS) is now generally defined as the sequencing technology that, by employing parallel sequencing processes, producing thousands or millions of sequence reads simultaneously. Since the GS20 was released as the first NGS sequencer on the market by 454 Life Sciences, the competition in the development of the new sequencers has become intense. In this review, we describe the current deep sequencing systems and discuss the application of advanced technologies in the field of hepatology.

Efficacy of lamivudine combined with adefovir dipivoxil versus entecavir monotherapy in patients with hepatitis B-associated decompensated cirrhosis: A meta-analysis

Whether the combination of lamivudine (LAM) plus adefovir (ADV) de novo is more effective than entecavir (ETV) monotherapy in patients with HBV-associated decompensated cirrhosis is still controversial. We searched seven randomized controlled trials that included 411 patients in this meta-analysis. There are 205 and 206 patients in these two groups separately. The pooled risk ratio (RR) and mean difference (MD) were used to assess the treatment effects. ETV monotherapy significantly improved Child-Turcotte-Pugh (CTP) scores (MD = 0.33, 95%CI [0.21-0.44], P < .00001), and was associated with lower rates of serum creatinine increase compared LAM + ADV combination therapy (RR = 4.76, 95%CI [1.11-20.33], P = .04) at 48 weeks. The reduction of alanine aminotransferase (ALT) levels, HBV DNA levels, the rate of ALT normalization, undetectable HBV DNA, HBV e antigen (HBeAg) loss, HBeAg seroconversion and mortality were similar between the two groups. ETV is more effective than LAM + ADV in improving CTP scores at 48 weeks. Both of the LAM + ADV and ETV had similar efficacy in improving virological and biochemical parameters at 48 weeks of follow-up. Furthermore, use of these agents in decompensated HBV patients was generally safe and well tolerated at 48 weeks. However, the nephrotoxicity of ADV, and the potential adverse effects of ETV should be considered and monitored during prolonged therapy.

Molecular epidemiology and clinical characteristics of hepatitis B identified through the French mandatory notification system

BACKGROUND & AIMS

Strains responsible for acute hepatitis B infections (AHB) in France have not been characterized. This study was first designed to analyze the molecular epidemiology of AHB and second to describe the differences between AHB and chronic hepatitis B (CHB) exacerbations.

METHODS

This prospective study was based on the French mandatory notification system for AHB. 147 samples corresponding to declared cases were shipped to a central laboratory for classification as AHB or CHB according to the level of anti-HBc IgM and anti-HBc avidity.

RESULTS

Based on biological marker values and file examination, 75 cases (59%) were classified as AHB. Independently of the acute or chronic status, genotype A (57%), D (22%) and E (14%) were the most prevalent and no phylogenetic clustering was observed among HBV sequences (n=68). Precore or basal core-promoter variants were not particularly associated with disease severity but were more prevalent in CHB. No antiviral resistant strains or immune-escape HBsAg was observed. HBV viral loads in AHB or CHB were comparable but with opposite distributions. ALT levels reached 10 times the upper normal value in 94% of AHB but only in 24% of CHB.

CONCLUSIONS

After rigorous classification, no major difference at the genetic level was found between HBV strains isolated from AHB and CHB. Absence of potentially deleterious variant detection is reassuring. When based upon HBsAg and anti-HBc IgM determination, AHB notification may falsely include more than 40% CHB, leading to an important risk of bias in national surveillance programs of AHB.

Absence of Hepatitis B Resistance Mutants before Introduction of Oral Antiviral Therapy

Introduction. The aim of this study was to assess whether hepatitis B virus drug resistant mutations antedated the widespread use of nucleos(t)ide analogues in treatment naïve patients. A number of reports have suggested that drug resistant mutants can be detected in apparently treatment naïve patients. Study. Fifty deidentified serum samples collected from 1986 to 1992 from patients with replicative chronic HBV infection at the University of Miami were genotyped and tested for resistance mutations using a line probe assay InnoLiPA HBV DR v2/v3. Serum HBV DNA was measured. All patients had documented chronic HBV infection with a detectable viral load, HBeAg seropositivity, and absence of HIV infection. Results. Of the 50 individuals included, 86% were male, mean age was 40 ± 12 years, and mostly genotype A. The mean HBV DNA was 126 pg/mL (range 6.4 to 557.0). No mutations were identified. Conclusions. The absence of drug induced mutations in these sera collected several years prior to the introduction of oral antiviral therapy suggests that these mutations do not occur in treatment naïve populations. Detection of drug resistance in an apparently treatment naïve subject suggests either unrecognized prior antiviral therapy or infection by an inoculum from a treatment experienced patient.

Combination lamivudine and adefovir versus entecavir for the treatment of naïve chronic hepatitis B patients: a pilot study

BACKGROUND

The aim of this study was to compare the effect of combination lamivudine (LAM) and adefovir dipivoxil (ADV) versus entecavir (ETV) monotherapy for naïve HBeAg-positive chronic hepatitis B (CHB) patients.

MATERIAL/METHODS

Fifty enrolled patients with CHB were evenly divided into 2 groups: a group treated with of lamivudine (LAM) (100 mg/day) plus adefovir (ADV) (10 mg/day) combination, and a group treated with entecavir (ETV) (0.5 mg/day). Serum levels of ALT, AST, creatinine, bilirubin, HBsAg, HBeAg and HBV viral load, and genotypic resistance were analyzed at 0, 12, 24, 52, and 104 weeks. HBV DNA levels were determined by real-time PCR and HBsAg and HBeAg by chemiluminescence. Serum levels of ALT, AST, creatinine, and bilirubin were measured by an automatic biochemical analyzer. Data analysis was performed with SPSS 12.0 software.

RESULTS

There were no significant differences in the virological response (VR) rates between LAM+ADV and ETV cohorts at 24, 52, and 104 weeks (P>0.05). The HBeAg seroconversion rates were 28% and 20%, and the biochemical response (BR) rates were 88% and 84% at week 104 in the LAM+ADV and ETV groups, respectively. The rates of undetectable HBV DNA, HBeAg seroconversion, and ALT normalization rates were similar in both cohorts. No virological breakthrough or serious adverse effects were noted for any patient during the study period.

CONCLUSIONS

Both LAM+ADV combination therapy and ETV monotherapy were effective and safe in the treatment of -naïve HBeAg-positive CHB patients. However, further studies are needed to obtain long-term results.

Drug-related mutational patterns in hepatitis B virus (HBV) reverse transcriptase proteins from Iranian treatment-naïve chronic HBV patients

BACKGROUND

Immunomodulators and Nucleotide analogues have been used globally for the dealing of chronic hepatitis B virus (HBV) infection. However, the development of drug resistance is a major limitation to their long-term effectiveness.

OBJECTIVES

The aim of this study was to characterize the hepatitis B virus reverse transcriptase (RT) protein variations among Iranian chronic HBV carriers who did not receive any antiviral treatments.

MATERIALS AND METHODS

Hepatitis B virus partial RT genes from 325 chronic in active carrier patients were amplified and directly sequenced. Nucleotide/amino acid substitutions were identified compared to the sequences obtained from the database.

RESULTS

All strains belonging to genotype D.365 amino-acid substitutions were found. Mutations related to lamivudine, adefovir, telbivudine, and entecavir occurred in (YMDD) 4% (n = 13), (SVQ) 17.23% (n = 56), (M204I/V + L180M) 2.45% (n = 8) and (M204I) 2.76% (n = 9) of patients, respectively.

CONCLUSIONS

RT mutants do occur naturally and could be found in HBV carriers who have never received antiviral therapy. However, mutations related to drug resistance in Iranian treatment-naïve chronic HBV patients were found to be higher than other studies published formerly. Chronic HBV patients should be monitored closely prior the commencement of therapy to achieve the best regimen option.

Prevalence and significance of Hepatitis B reverse transcriptase mutants in different disease stages of untreated patients

AIMS

Hepatitis B virus (HBV) reverse transcriptase (RT) mutants, which have not been well characterized according to different disease stages. This study aimed to characterize the profiles of naturally occurring mutations in the HBV RT region and their associated clinical outcomes.

METHODS

HBV RT region mutations and genotypes were determined by PCR-direct sequencing and compared with p-distance model.

RESULTS

Among 467 consecutive eligible patients (262 chronic hepatitis B patients, 105 cirrhotic patients and 100 hepatocellular carcinoma patients), the nucleos(t)ide analogues-related mutations (rtI169T, rtV173L, rtL180M, rtA181T, rtS202C, rtM204I/V, rtN236T) were found. The p-distance value reached a peak in the age of 20-30 years in the CHB patients and in the age of 40-45 years in the cirrhotic patients and hepatocellular carcinoma patients. The naturally occurring mutation, rtS106C mutation was higher in chronic hepatitis B patients (14/100, 14.0%) and cirrhotic patients (14/100, 14.0%) than that in hepatocellular carcinoma patients (4/100, 4.0%, P = 0.013). And the rtD134E/G/N/S mutations were also higher in chronic hepatitis B patients (22/100, 22.0%) and cirrhotic patients (21/100, 21.0%) than that in hepatocellular carcinoma patients (10/100, 10.0%, P = 0.021 and P = 0.032 respectively). The mutation frequencies in A-B interdomain were higher in cirrhotic patients (101/1900, 5.3%) than that in hepatocellular carcinoma patients (68/1900, 3.6%) (P = 0.009).

CONCLUSIONS

The nucleos(t)ide analogues-related mutations do exist in treatment naive patients with different disease stages. rtS106C, rtD134E/G/N/S and A-B interdomain mutations may be associated with necro-inflammation, immune response and cirrhosis development at ages older than 40.

Genotype-specific mutations in the polymerase gene of hepatitis B virus potentially associated with resistance to oral antiviral therapy

The evolution of hepatitis B virus (HBV) and the role of different variants during antiviral therapy may be influenced by HBV genotype. We have therefore analysed substitutions potentially related to nucleos(t)ide analogues (NAs) resistance at 42 positions within RT-region in a cohort of patients with chronic hepatitis B in relation to HBV-genotype. RT mutations analysis was performed by direct sequencing in 200 NAs-naïve patients and in 64 LAM or LAM+ADV experienced patients with NAs resistance, infected mainly by HBV-genotypes D and A. 27 polymorphic-sites were identified among the 42 positions analysed and 64 novel mutations were detected in 23 positions. Genotype-D displayed the highest mutation frequency (6.4%) among all HBV-genotypes analysed. Single or multiple mutations were detected in 80% of naïve patients. Overall, the most frequent single mutations were at residues rt54, rt53 and rt91 which may associate with significantly lower HBV-DNA levels (p=0.001). Comparison with sequencing data of patients failing LMV or LAM+ADV therapy revealed an higher frequency of novel genotype-specific mutations if compared with naïve patients: 3 mutations under LAM monotherapy in HBV-D (rtS85F; rtL91I; rtC256G) and 3 mutations under ADV therapy in HBV-A (rtI53V; rtW153R; rtF221Y). In HBV-D treated patients the dominant resistance mutation was rtL80V (31.4%) and rtM204I (60%) in LAM+ADV group while LAM-treated patients showed a preference of rtM204V (51.9%). Interestingly, none of HBV-A patients had mutation rtM204I under ADV add-on treatment but all of them had the "V" AA substitution. These results suggested that in patients with CHB, HBV-genotype might be relevant in the evolution and development of drug resistance showing also different mutation patterns in the YMDD motif between HBV genotype D and A.

Dynamics of hepatitis B virus quasispecies in association with nucleos(t)ide analogue treatment determined by ultra-deep sequencing

BACKGROUND AND AIMS

Although the advent of ultra-deep sequencing technology allows for the analysis of heretofore-undetectable minor viral mutants, a limited amount of information is currently available regarding the clinical implications of hepatitis B virus (HBV) genomic heterogeneity.

METHODS

To characterize the HBV genetic heterogeneity in association with anti-viral therapy, we performed ultra-deep sequencing of full-genome HBV in the liver and serum of 19 patients with chronic viral infection, including 14 therapy-naïve and 5 nucleos(t)ide analogue(NA)-treated cases.

RESULTS

Most genomic changes observed in viral variants were single base substitutions and were widely distributed throughout the HBV genome. Four of eight (50%) chronic therapy-naïve HBeAg-negative patients showed a relatively low prevalence of the G1896A pre-core (pre-C) mutant in the liver tissues, suggesting that other mutations were involved in their HBeAg seroconversion. Interestingly, liver tissues in 4 of 5 (80%) of the chronic NA-treated anti-HBe-positive cases had extremely low levels of the G1896A pre-C mutant (0.0%, 0.0%, 0.1%, and 1.1%), suggesting the high sensitivity of the G1896A pre-C mutant to NA. Moreover, various abundances of clones resistant to NA were common in both the liver and serum of treatment-naïve patients, and the proportion of M204VI mutants resistant to lamivudine and entecavir expanded in response to entecavir treatment in the serum of 35.7% (5/14) of patients, suggesting the putative risk of developing drug resistance to NA.

CONCLUSION

Our findings illustrate the strong advantage of deep sequencing on viral genome as a tool for dissecting the pathophysiology of HBV infection.

Response to tenofovir monotherapy in chronic hepatitis B patients with prior suboptimal response to entecavir

Both entecavir (ETV) and tenofovir (TDF) are potent antiviral agents for hepatitis B virus (HBV). Suboptimal response (SOR) following antiviral therapy is associated with an increased risk of subsequent treatment failure and viral resistance. It remains unclear whether switching to TDF is a reasonable approach in patients with SOR to ETV treatment. This study was aimed to determine how HBV patients with SOR to ETV respond to TDF monotherapy. Data of patients with SOR to ETV (failure to achieve >1 log(10) HBV-DNA reduction during the last 24 weeks of ETV treatment) who were switched to TDF monotherapy during 2005 and 2010 were reviewed. Treatment adherence was assessed by pill-count. Fourteen patients (2.9%) were identified from a total cohort of 482 ETV-treated patients. All 14 patients were Chinese and were infected with HBV genotype C (71%) or B (29%). Nine patients were men, and the median age was 41.5 years (19-64). Twelve were treatment naïve (one lamivudine- and one peginterferon-experienced patient); 85.7% were HBeAg positive. The median baseline HBV-DNA was 7.55 (5.30-9.40) log(10) copies/mL, and 57% had abnormal serum alanine aminotransferase (ALT) levels. Precore and/or basal core promoter mutations were detected in four patients, whereas no genotypic resistance was detected at baseline and before switching to TDF. The median duration of ETV treatment was 64.5 (26-126) weeks. The median HBV-DNA at the time of switching to TDF was 3.69 (3.00-4.90) log(10) copies/mL. The median HBV-DNA reduction from baseline and during the last 6-month observation period prior to switching to TDF was 4.04 (0.51-6.06) log(10) and 0.43 (-0.09-1.13) log(10) copies/mL, respectively. After the switching to TDF, all 14 patients (100%) achieved undetectable HBV-DNA and ALT normalization within a median duration of 30 weeks. In 12 patients who were HBeAg positive, HBeAg seroconversion was observed in two patients after TDF treatment of 75- and 84-weeks duration. There was no virological breakthrough observed after switching to TDF with a median follow-up period of 50 (24-160) weeks. TDF treatment was safe and well tolerated. In conclusion, suboptimal response to ETV is rare (approximately 3%). TDF monotherapy is safe and very effective in the management of HBV patients with SOR to ETV.

Characterization of drug-resistance mutations in HBV D-genotype chronically infected patients, naïve to antiviral drugs

Presence of drug-resistance mutations in drug-naïve hepatitis B virus (HBV) infected patients can seriously compromise response to antiviral treatment. Therefore, our study was aimed at defining the prevalence of HBV drug-resistance in a population of 140 patients, all infected with HBV-D-genotype (the most common HBV-genotype in Eastern Europe, Mediterranean countries and Middle East) and naïve to antiviral therapy. HBV reverse-transcriptase (RT) region was sequenced and analyzed for 20 mutations, confirmed by in vitro studies as associated with resistance to nucleos(t)ide HBV-RT inhibitors (rtL80I/V-rtI169T-rtV173L-rtL180M-rtA181T/V/S-rtT184A/S/G/C-rtA194T-rtS202C/G/I-rtM204V/I-rtN236T-rtM250V). Amino acid changes at other six RT positions, potentially associated with resistance, were also analyzed (rtV84M-rtV191I-rtV207L-rtV214A-rtQ215S-rtI233V). Overall, only 2/140 (1.4%) patients carried primary drug-resistance mutations [rtA181V (0.7%), and rtA194T (0.7%)], while 3/140 (2.1%) patients harbored the secondary mutations rtV173L (1.4%) and rtL180M (0.7%). Additionally, five polymorphic mutations, with a suggested role in drug resistance, were detected [rtQ215S (12.8%), rtI233V (4.3%), rtV214A (3.6%), rtV191I (0.7%), rtV207L (0.7%)]. Notably, no YMDD mutations, namely rtM204V/I, were found. Taken together, the rate of important drug resistance mutations in naïve HBV D-genotype infected patients is today very low, and suggests the potential full efficacy of new-generation antiviral drugs used in first line therapy. Whether such low rate can be extrapolated to non HBV-D subtypes, requires a detailed investigation to be performed in a different cohort of patients.

Large-scale survey of naturally occurring HBV polymerase mutations associated with anti-HBV drug resistance in untreated patients with chronic hepatitis B

Drug resistance is a major limitation for the long-term efficacy of antiviral therapy with nucleos(t)ide analogues (NAs) in chronic hepatitis B (CHB). Antiviral resistance mutations may pre-exist in the overall viral population of untreated patients. We aimed to assess the prevalence of such hepatitis B virus (HBV) variants in a large cohort of NAs-naïve patients with CHB and to explore possible association with viral and host variables. Serum samples from 286 NAs-naïve consecutive patients with CHB were tested for serum HBV-DNA, and 255 of them having HBV-DNA > 1000 IU/mL were further analysed for drug resistance mutations by INNO-LiPA HBV DRv2/v3. NAs-naïve patients analysed were mainly men (73%), Caucasians (85%), hepatitis B e Antigen (HBeAg) negative (79%) and genotype D (69%), with a mean age of 43.2 ± 13.4 years. HBV mutations associated with antiviral drug resistance were detected in 13 (5%) patients: three patients infected with HBV genotype C had the rtM204V + rtL180M mutations associated with lamivudine (LMV) resistance. Four patients had the rtI233V mutation that may reduce sensitivity to adefovir, and three patients had the rtM250L/V mutation typical of entecavir resistance. LMV compensatory mutations rtL80V and rtV173L were seen in two and one patients, respectively. No relationship was seen between presence of resistant or compensatory mutations and HBV-DNA levels, HBeAg/anti-HBe status or previous IFN therapy. These results confirm that HBV mutations, which confer resistance against currently available anti-HBV NAs, may already exist in patients who have never received the drug.

Antiviral resistance mutations and genotype-associated amino acid substitutions in treatment-naïve hepatitis B virus-infected individuals from the Indian subcontinent

BACKGROUND/AIMS

Antiviral resistance is a major challenge to the treatment currently available for hepatitis B virus (HBV). In this study, mutations that may affect the antiviral efficacy in treatment-naïve HBV-infected individuals were analyzed.

METHODS

Ninety-seven treatment-naïve HBV-infected individuals were included in this study. HBV reverse transcriptase (rt) domains were sequenced and nucleotide differences were compared to GenBank wild-type sequences. Furthermore, HBV genotypes, subgenotypes and subtypes were determined by analyzing surface gene sequences.

RESULTS

An adefovir-related rtI233V mutation was identified in 4 subjects. The rtS213T lamivudine and entecavir refractory mutant was presented in 3 individuals. Altogether, drug-related, atypical and novel HBVrt amino acid substitutions were seen in 73 positions. The HBV genotypes A, C, D and G were depicted in 15, 21, 60 and 1 individuals, respectively. There were 17 HBVrt amino acid substitutions that are associated with certain genotypes of HBV. Mutations in HBVrt corresponded to established surface gene mutations in 9 patients.

CONCLUSION

This data shows that antiviral-resistant HBV strains do exist in treatment-naïve individuals in this region. Further studies are essential to characterize the role of HBVrt amino acid substitutions in response to anti-HBV therapy.

Lamivudine-resistance mutations can be selected even at very low levels of hepatitis B viraemia

OBJECTIVE

To investigate lamivudine (LAM)-resistance profiles of hepatitis B virus (HBV) at the early stages of virological breakthrough (serum HBV-DNA 12-345IU/ml) or when HBV-DNA is undetectable.

METHODS

Sixty-four HBV-mono-infected patients were enrolled: 25 had virological breakthrough with serum HBV-DNA ranging from 12 to 345IU/ml during first-line LAM-monotherapy; 24 were on LAM-monotherapy, and 15 were on LAM+adefovir dipivoxil (ADV) with undetectable serum HBV-DNA (<12IU/ml).

RESULTS

HBV-reverse transcriptase was successfully sequenced in 22 (88.0%) LAM-treated patients with HBV-DNA between 12 and 345IU/ml, and in 12 (30.8%) patients receiving LAM (±ADV) with HBV-DNA<12IU/ml. Drug-resistance mutations were observed in 17 (77.2%) LAM-treated patients with virological breakthrough: 8 M204V, 7 M204I, 1 M204I/V, and 1 A181T. One or ≥2 compensatory mutations were found in 10 (58.8%) and in 4 (23.5%) patients. Drug-resistance mutations were present also in patients with undetectable serum HBV-DNA: M204I was detected in 2 patients receiving LAM-monotherapy, and V84M in 1 patient receiving LAM+ADV.

CONCLUSION

Overall findings support the existence of drug-resistance mutations even at very low levels of viral replication. The persistence of low-level HBV replication and consequent drug-resistance emergence should be considered when choosing therapeutic strategies.