Frequency and mutation patterns of resistance in patients with chronic hepatitis B infection treated with nucleos(t)ide analogs in add-on and switch strategies

Molecular Epidemiology of Hepatitis B Virus in Turkish Cypriot

There is an increased demand for molecular and epidemiological information regarding Hepatitis B Virus (HBV) infection as the disease severity depends on these specifications. We have aimed to analyze nucleos(t)ide analogues (NA) resistance and typical HBsAg escape mutations with the dispersion of HBV genotype/subgenotype/HBsAg serotypes on overlapping pol/S gene regions in the Turkish population. Samples were collected in Northern Cyprus. Reverse transcriptase (rt) region between 80–250 amino acids were amplified. Typical HBsAg escape mutations were determined as HBIg escape (6.48%), vaccine escape (8.34%), HBsAg misdiagnosis (9.25%), and immune escape mutations (8.34%). NAs resistances were determined as primary (2.78%), partial (2.78%), and compensatory mutations (26.85%) in overlapping pol/S gene region. The study patients were predominantly infected with HBV genotype D/D1 (98%). However, the predominant HBsAg serotype was ayw2 (99%). The most common NA resistance mutation was rtQ215H/P/S (16.67%), however, for S gene the misdiagnosis mutations were observed most frequently (9.25%). We can conclude that HBV D/D1 is the dominant strain and ayw2 is the dominant serotype in the Turkish Cypriot. Cyprus is an island located in the Eastern Mediterranean region, and it is, therefore, a key location for human trafficking and immigration; as a result of this reputation, it is necessary to analyze HBV phylogenetically for local dynamics, and our results indicate that treatment naïve population is prone to these pol/S gene mutations. However, if HBV strains were also analyzed among Greek Cypriots too, this would enable a complete island survey. With this work, we believe that we have enlightened this subject for further research.

Evaluation of drug resistance mutations in patients with chronic hepatitis B

Mutations occurring in viral polymerase gene of hepatitis B virus (HBV) due to the use of nucleos(t)id analogs reduce the activity of the drugs by causing antiviral resistance. In this study, it was aimed to evaluate mutations responsible for drug resistance and drug resistance mutation rates in patients followed up by the diagnosis of chronic hepatitis B (CHB). A total of 318 CHB patients were included in the study. HBV mutations were detected using the INNO-LiPA commercial kit based on the reverse hybridization principle. Drug resistance mutation was detected in 46.86% (149/318) of the patients. The rates of drug resistance were found 36.79% (117/318) for lamivudine resistance, 12.58% (40/318) for entecavir (ETV), and 7.86% (25/318) for adefovir. In 10 patients, the possible tenofovir (TDF) resistance (3.14%) was found. Single-drug and double-drug resistances were detected in 34.59% and in 11.01% of the patients, respectively. Triple drug resistance was detected in only 1.26% of the patients. Unlike various studies in Turkey and in other countries, remarkable resistance to ETV and TDF were found in this study. The high rate of the probable TDF resistance was striking, with 3.14%.

Pre-existing mutations in reverse transcriptase of hepatitis B virus in treatment-naive Chinese patients with chronic hepatitis B

High rate of viral replication and lacking of proofreading activity in hepatitis B virus (HBV) polymerase lead to the generation of mutations in HBV virus. Mutations in the reverse transcriptase (RT) region of HBV polymerase are demonstrated to be strongly associated with drug resistance during antiviral treatment. However, the presence of mutations as well as its clinical significance in treatment-naïve hepatitis patients (defined as pre-existing mutations) need to be further investigated. In the present study, a total of 168 serum samples from treatment-naive chronic hepatitis B (CHB) patients were collected, and the RT region of HBV polymerase was sequenced. The results showed that pre-existing mutations in the RT region of HBV polymerase were detected in 43 of 168 (25.6%) treatment-naive CHB patients within which there were no well-characterized primary nucleotide analogs (NAs) resistance sites. Three dominant sites at rt191, rt207 and rt226 were found mutant in 7(16.28%), 8(18.60%), and 14(32.56%) samples respectively among these 43 patients. No significant correlation was found between pre-existing mutations and gender, age, HBV genotype, ALT, HBeAg or HBV DNA loads. However, patients with pre-existing RT mutations under HBeAg sero-negative status exhibited decreased HBV DNA loads, which contributed to the decreased HBV DNA loads in the total HBeAg sero-negative patients. The above investigation indicated that there was a prevalence of pre-existing mutations in RT region of HBV polymerase which might affect the serum HBV DNA level in treatment-naive CHB patients. Its effects on the occurrence of NAs resistance and the prognosis after treatment need to be further investigated.

Intracellular levels of hepatitis B virus DNA and mutational patterns of the polymerase gene of hepatitis B virus in peripheral blood mononuclear cells of patients with lamivudine or telbivudine resistance

Studies are limited regarding the association between the quantity of hepatitis virus B (HBV) DNA loads in serum and peripheral blood mononuclear cells (PBMCs) in patients with drug resistance and few studies focus on the mutational pattern of the polymerase gene of HBV in PBMCs of patients with drug resistance. The aim of the present study was to investigate the association between the quantity of HBV DNA loads in serum and PBMCs in patients with lamivudine (LAM) or telbivudine (LdT) resistance and to explore the mutational pattern of the polymerase gene of HBV in PBMCs of these patients. A total of 51 patients underwent antiviral therapy with LAM or LdT for at least half a year. The present study applied quantitative polymerase chain reaction for the quantification of total HBV DNA, and direct sequencing was used to detect the mutation. In total, 31 patients (60.78%) were detected to have drug resistance. The mean serum HBV DNA levels were significantly higher than the HBV DNA levels of PBMCs, whether in patients with LAM or LdT resistance. The PBMCs HBV DNA loads were correlated with the serum HBV DNA loads in the two groups. Three and two mutational patterns were found in the serum of patients with LAM and LdT resistant, respectively. In total, 85.71% of patients with LAM resistance and 75.00% of patients with LdT resistance presented the same mutational pattern in paired PBMCs and serum. The HBV DNA levels in the PBMCs of patients with LAM or LdT resistance were significantly lower than those in serum and there were positive correlations between them. The majority of the mutational patterns of the polymerase gene of HBV DNA in PBMCs were the same as those in the paired serum. These findings may help to increase knowledge regarding HBV drug resistance.

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.

Effects of antiviral therapy on the recurrence of hepatocellular carcinoma after curative resection or liver transplantation

CONTEXT

Hepatocellular carcinoma (HCC) is a fatal disease. Chronic hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infection is the major cause of HCC. High viral replication rate and related hepatic/systematic inflammation are the major risk factors in HCC recurrence after hepatectomy or liver transplantation.

EVIDENCE ACQUISITION

Some of the carcinogenesis-related HBV mutations are also associated with poor prognosis for HCC patients. Antiviral therapy is an option for improving HCC prognosis after surgery. In case of HBV-associated HCC, treatment with interferon and nucleos(t)ide analogues (NAs), especially interferon, is effective in improving the prognosis. However, long-term use of NAs increases the possibility of developing drug-resistant viral mutations such as the HBV rtA181T/sW172 mutation, which increases the risk of HCC recurrence.

RESULTS

In cases of HCV-associated HCC, standard interferon with or without ribavirin therapy is effective in improving the prognosis of HCV-associated HCC; however, some HCV mutations, such as the amino acid substitution M91L, are associated with treatment failure and a poor prognosis. Therapeutic efficacy needs to be confirmed using largescale, randomized, placebo-controlled clinical trials.

CONCLUSIONS

Surveillance of viral mutations during antiviral treatment and a better understanding of the associations of HCC recurrence with viral load, inflammation-associated signaling, and environmental factors can aid the development of more effective strategies for the prevention of HCC recurrence after surgery.