rtL180M mutation of hepatitis B virus is closely associated with frequent virological resistance to adefovir dipivoxil therapy

High frequency of Lamivudine and Telbivudine resistance mutations in hepatitis B virus isolates from human immunodeficiency virus co-infected patients on highly active antiretroviral therapy in Bucaramanga, Colombia

Hepatitis B virus (HBV) antiviral Resistance-Associated Mutations (RAMs) in human immunodeficiency virus (HIV) coinfected patients undergoing highly active antiretroviral therapy (HAART) are complex and incompletely understood. We aimed to determine the prevalence of HBV coinfection, HBV genotypes, and RAMs in a cohort of people living with HIV (PLWH) in the northeastern region of Colombia. This cross-sectional study was carried out between February 2013 and February 2014. Virological, immunological and HAART data were collected from clinical records. In-house nested PCR and Sanger sequencing of the HBV pol gene were used to identify coinfections, genotypes, RAMs and HBV s antigen (HBsAg) escape mutants. Among 275 PLWH, HBV coinfection was confirmed in 32 patients (11.6%), of whom nine (28.2%) were HBsAg positive (active hepatitis B), and 23 (71.8%) were occult hepatitis B infections (OBI). All HBV sequences (n = 23) belonged to the genotype F3. Among HIV/HBV coinfections, 71.9% had CD4+ T cell counts above 200 cells/mm3 and 37.5% had undetectable HIV viral loads. The RAMs rtL80I, rtL180M, and rtM204V, which confer resistance to Lamivudine/Telbivudine and partially resistant to Entecavir, were found in all HBV isolates. An unknown rt236Y mutation to Tenofovir was also identified. Most patients under HAART received first-generation HBV antiviral therapy with a low genetic barrier to resistance. Antiviral Drug-associated Potential Vaccine-escape Mutations (ADAPVEMs) in the S gene were observed in all isolates ranging from 1-20 amino acid substitutions. However, no vaccine escape mutants were detected. In Conclusion, these findings highlight the importance of HBV molecular screening, antiviral resistance monitoring and new guidelines for PLWH to overcome RAMs and prevent HBV-related liver disease.

Potential resistant mutations within HBV reverse transcriptase sequences in nucleos(t)ide analogues-experienced patients with hepatitis B virus infection

This study was performed to analyze the potential resistant mutations within HBV reverse transcriptase (RT) sequences against nucleos(t)ide analogues (NA). HBV DNA RT region spanning from amino acid 169 to 250 was amplified and sequenced from 435 HBV patients who experienced NA treatment. Among study’s cohort, genotypes B and C infected patients were 55.9% and 44.1%, respectively. Mutations were recorded in 54.7% (238/435) patients at 22 positions. Genotype C displayed significant higher frequency of potential NA resistant mutations than genotype B (63.0% vs. 48.1%, P = 0.003). Moreover, eight mutation sites, including 180, 181, 191, 200, 202, 221, 229 and 224, in genotype C showed significant higher frequencies than in genotype B. In contrast, mutation at site 236 was more common in genotype B. Notably, 11 mutations at position 169, 202, 250, 173, 180, 200, 207, 214, 237, 242 and 245 coexisted with M204I or V. Substitutions at nine non-classical mutation sites (191, 207, 213, 218, 221, 224, 229, 238 and 242) were detected in patients with virological breakthrough. Particularly, tenofovir (TDF) resistance was observed in one patient undergoing TDF monotherapy and experienced several NA treatment before. These results might provide clinical useful information under antiviral therapy.

Clinical Implications of Hepatitis B Virus RNA and Covalently Closed Circular DNA in Monitoring Patients with Chronic Hepatitis B Today with a Gaze into the Future: The Field Is Unprepared for a Sterilizing Cure

. Chronic hepatitis B virus (HBV) infection has long remained a critical global health issue. Covalently closed circular DNA (cccDNA) is a persistent form of the HBV genome that maintains HBV chronicity. Decades of extensive research resulted in the two therapeutic options currently available: nucleot(s)ide analogs and interferon (IFN) therapy. A plethora of reliable markers to monitor HBV patients has been established, including the recently discovered encapsidated pregenomic RNA in serum, which can be used to determine treatment end-points and to predict the susceptibility of patients to IFN. Additionally, HBV RNA splice variants and cccDNA and its epigenetic modifications are associated with the clinical course and risks of hepatocellular carcinoma (HCC) and liver fibrosis. However, new antivirals, including CRISPR/Cas9, APOBEC-mediated degradation of cccDNA, and T-cell therapies aim at completely eliminating HBV, and it is clear that the diagnostic arsenal for defining the long-awaited sterilizing cure is missing. In this review, we discuss the currently available tools for detecting and measuring HBV RNAs and cccDNA, as well as the state-of-the-art in clinical implications of these markers, and debate needs and goals within the context of the sterilizing cure that is soon to come.

Molecular characterization of occult hepatitis B virus infection in patients with end-stage liver disease in Colombia

Background

Hepatitis B virus (HBV) occult infection (OBI) is a risk factor to be taken into account in transfusion, hemodialysis and organ transplantation. The aim of this study was to identify and characterize at the molecular level OBI cases in patients with end-stage liver disease.

Methods

Sixty-six liver samples were obtained from patients with diagnosis of end-stage liver disease submitted to liver transplantation in Medellin (North West, Colombia). Samples obtained from patients who were negative for the surface antigen of HBV (n = 50) were tested for viral DNA detection by nested PCR for ORFs S, C, and X and confirmed by Southern-Blot. OBI cases were analyzed by sequencing the viral genome to determine the genotype and mutations; additionally, viral genome integration events were examined by the Alu-PCR technique.

Results

In five cases out of 50 patients (10%) the criteria for OBI was confirmed. HBV genotype F (subgenotypes F1 and F3), genotype A and genotype D were characterized in liver samples. Three integration events in chromosomes 5q14.1, 16p13 and 20q12 affecting Receptor-type tyrosine-protein phosphatase T, Ras Protein Specific Guanine Nucleotide Releasing Factor 2, and the zinc finger 263 genes were identified in two OBI cases. Sequence analysis of the viral genome of the 5 OBI cases showed several punctual missense and nonsense mutations affecting ORFs S, P, Core and X.

Conclusions

This is the first characterization of OBI in patients with end-stage liver disease in Colombia. The OBI cases were identified in patients with HCV infection or cryptogenic cirrhosis. The integration events (5q14.1, 16p13 and 20q12) described in this study have not been previously reported. Further studies are required to validate the role of mutations and integration events in OBI pathogenesis.

Mutational analysis of reverse transcriptase and surface proteins of patients with partial virological response during mono and combination antiviral therapies in genotype D chronic hepatitis B

Introduction

The mutational pattern of chronic Hepatitis B virus (HBV) is unclear in patients who show incomplete response to antiviral therapy. The aims of this study were 1) to determine the benefit of combination therapy with adefovir dipivoxil (ADV) and Lamivudine (LAM) versus ADV or LAM alone in maintaining virological, biochemical and histological responses and 2) to investigate the patterns of mutations in the reverse transcriptase and surface proteins of HBV with LAM and/or ADF-resistant in partially-responded chronic hepatitis B (CHB) patients.

Methods

The study group consisted of 186 chronic HBV carriers who were admitted to the Tehran Hepatitis Network from 2010 to 2013. We retrospectively selected 86 patients who partially responded to different nucleoside analogue regimens. After 48 weeks of therapy, five groups of patients were defined including eight Lamivudine (LAM) Group (I), 30 Adefovir (ADV) Group (II), 16 ADV add on LAM Group (III), 32 ADV+LAM Group (IV), and 100 controls (no therapy). Reverse transcriptase (RT) and surface genes were amplified and sequenced for mutational analysis.

Results

All groups showed differences between mean values for age, gender, alanine transaminase (ALT), aspartate transaminase (AST), and HBV DNA levels groups showed significant differences than other groups (p < 0.05). The mutation frequencies for groups were I (1.7%), II (1.39%), III (2.28%), IV (2.0%), and V (0.38%). T54N, L80I/V, I91L/V, L180M, M204I/V, Q215P/S, and F221Y/S showed the highest number of mutations in all groups with different frequencies. Four new, unreported mutations were found.

Conclusion

Those patients who failed to respond in the first 48 weeks, whether they were receiving mono or combination therapy, should be tested genotypically, for the early modification of treatment.

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.

Nucleoside/nucleotide analog inhibitors of hepatitis B virus polymerase: mechanism of action and resistance

Hepatitis B virus (HBV) polymerase and human immunodeficiency virus (HIV) reverse transcriptase are structurally related. However, the HBV enzyme has a protein priming activity absent in the HIV enzyme. Approved nucleoside/nucleotide inhibitors of the HBV polymerase include lamivudine, adefovir, telbivudine, entecavir and tenofovir. Although most of them target DNA elongation, guanosine and adenosine analogs (e.g. entecavir and tenofovir, respectively) also impair protein priming. Major mutational patterns conferring nucleoside/nucleotide analog resistance include the combinations rtL180M/rtM204(I/V) (for lamivudine, entecavir, telbivudine and clevudine) and rtA181V/rtN236T (for adefovir and tenofovir). However, development of drug resistance is very slow for entecavir and tenofovir. Novel nucleoside/nucleotide analogs in advanced clinical trials include phosphonates similar to adefovir or tenofovir, and new tenofovir derivatives with improved pharmacological properties.

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.

Hepatitis B e antigen predicts delayed reduction of HBV DNA without viral breakthrough with adefovir dipivoxil and lamivudine: a 5-year study of patients with hepatitis B with lamivudine resistance

To clarify the factors associated with delayed reduction of HBV DNA during combination treatment with adefovir dipivoxil (ADV) and lamivudine (LAM) for patients with LAM-resistant hepatitis B virus (HBV), factors including patient characteristics, viral mutations, and drug metabolism were investigated during a 5-year observation period. Delayed reduction of HBV DNA was defined as delayed viral response of detectable HBV DNA after 3 years of combination therapy. Of 67 consecutive patients, 47 attained undetectable HBV DNA after 3 years of combination therapy, and the mean therapeutic duration was 5 years (range: 3.0-8.4 years). The patients with delayed viral response had high levels of HBV DNA and HBe antigen, while those with negative or low levels of HBe antigen were also negative for HBV DNA, even if they had high levels of HBV DNA. In the multivariate analysis with the proportional hazards model, a high baseline level of HBe antigen was negatively associated with viral decline to an undetectable level (P = 0.013). A higher baseline of HBe antigen corresponded to a lower annual decline in HBV DNA (R = -0.38, P = 0.004). No patients showed ADV-resistant mutations in the HBV reverse transcriptase region. Trough concentrations of LAM and ADV showed no clear associations with viral response. HBe antigen levels at the initiation of therapy, and reductions in these levels during therapy are predictive of the therapeutic response to combination therapy with ADV and LAM for patients with LAM-resistant HBV.

Analysis of mutations in the reverse transcriptase domain of HBV polymerase in adefovir-resistant HBV patients

AIM: To study the characteristics of the B domain of the HBV polymerase gene in adefovir-resistant HBV patients.

METHODS: One hundred and seven patients with chronic hepatitis B treated with adefovir (ADV) (including 73 ADV-naïve patients and 34 LAM-resistant patients) at our hospital were selected. The B-C regions of the RT and S genes were amplified by PCR using specific primers flanking these regions. The PCR products were directly analyzed by sequencing. The differences in nucleotide and amino acid sequences and mutation patterns of the RT region were classified using Chromas2.0 software. HBV genotypes were analyzed using Clustalx1.81.msw.

RESULTS: Of the 107 patients, 36 had rtA181V mutation, 43 had rtA181T, 47 had rtN236T, 20 had rtM204I/V ± rtL180M, and 12 had other ADV - related mutations. In ADV-naïve patients, 27 (36.99%) had rtA181V/T, 14 (19.18%) had rtN236T, 28 (38.36%) had rtA181V/T + rtN236T, and 4 (5.48%) had other mutations. In LAM-resistant patients, 21 (61.76%) had rtA181V/T, 2 (5.88%) had rtN236T, 3 (8.82%) had rtA181V/T + rtN236T, and 8 (23.53%) had other mutations. rtA181T/V and rtN236T mutations were not detected in 12 patients, but they had rtA181S/C (2 cases), rtV214I/A (3 cases), rtQ215H (1 case), or rtH/N238S/T/R/A/K (6 cases), which are ADV resistance-related mutations.

CONCLUSION: The major ADV resistance-related mutations are rtA181T/V and rtN236T in ADV-naïve patients, and rtA181V/T in LAM-resistant patients.