Molecular epidemical characteristics of Lamivudine resistance mutations of HBV in southern China

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.

Association between clinical features and YMDD mutations in patients with chronic hepatitis B following lamivudine therapy

The aim of the present study was to investigate the correlation between feature and genotype with regard to the tyrosine-methionine-aspartate-aspartate (YMDD) mutation in chronic hepatitis B patients after lamivudine (LAM) therapy. A total of 30 patients with chronic hepatitis B were recruited, who underwent one year of LAM therapy. The patients' alanine aminotransferase (ALT) level and hepatitis B envelope antigen (HBeAg) seroconversion were evaluated, hepatitis B virus (HBV) DNA was genotyped using a new genotyping method and YMDD mutations were analyzed prior to treatment and at 6 and 12 months after LAM treatment. Furthermore, the secondary protein structure of the HBV DNA polymerase gene (P gene) was analyzed. Following treatment, the results suggested that LAM therapy improved ALT normalization. There was no correlation between clinical effects and ALT level before treatment. After 12 months treatment, the rate of HBeAg loss increased and the rate of HBeAg seroconversion decreased linearly with the rise of baseline ALT level. While ALT normalization and HBeAg seroconversion were highest in patients with HBV genotype B, HBeAg loss and HBVDNA loss were highest in those with genotype C. The effect was predominant in genotype D. No YMDD mutations were identified prior to 6 months of LAM therapy. The rate of YMDD mutations after 12 months LAM therapy was 12.12%. Two patients with rtM204V + rtL180M belonged to genotype C and another patient with rtL180M alone belonged to genotype D. The turn of secondary protein structure of P gene changed to β sheet when a rtM204V mutation occurred, and no change of secondary protein structure was associated with the rtL180M mutation. Thus, the present results indicate that one year of LAM therapy is able to improve ALT normalization. Long-term LAM therapy may induce YMDD mutation and drug resistance.

Tenofovir disoproxil fumarate is superior to lamivudine plus adefovir in lamivudine-resistant chronic hepatitis B patients

AIM: To assess the efficacy of tenofovir disoproxil fumarate (TDF) in lamivudine (LAM)-resistant patients with a suboptimal response to LAM plus adefovir (ADV).

METHODS: We retrospectively analyzed the efficacy of switching to tenofovir disoproxil fumarate in suboptimal responders to lamivudine plus adefovir. Charts were reviewed for LAM-resistant chronic hepatitis B (CHB) patients who visited the Zhejiang Province People’s Hospital and The First Affiliated Hospital, College of Medicine, Zhejiang University, from June 2009 to May 2013. Patients whose serum hepatitis B virus (HBV) DNA remained detectable despite at least 6 mo of LAM plus ADV combination therapy were included. Patients with a suboptimal response to LAM plus ADV were randomized to switch to TDF monotherapy (300 mg/d orally; TDF group) or to continuation with LAM (100 mg/d orally) plus ADV (10 mg/d orally; LAM plus ADV group) and were followed for 48 wk. Serum HBV DNA was determined at baseline and weeks 4, 12, 24, 36, and 48. HBV serological markers and biochemistry were assessed at baseline and weeks 12, 24, and 48. Resistance surveillance and side effects were monitored during therapy.

RESULTS: Fifty-nine patient were randomized to switch to TDF (n = 28) or continuation with LAM plus ADV (n = 31). No significant differences were found between the groups at baseline. Prior to TDF therapy, all patients had been exposed to LAM plus ADV for a median of 11 mo (range: 6-24 mo). No difference was seen in baseline serum HBV DNA between the two groups [5.13 ± 1.08 log₁₀ copies/mL (TDF) vs 5.04 ± 31.16 log₁₀ copies/mL (LAM + ADV), P = 0.639]. There was no significant difference in the rates of achieving complete virological response (CVR) at week 4 between the TDF and LAM + ADV groups (17.86% vs 6.45%, P = 0.24). The rate of achieving CVR in the TDF and LAM plus ADV groups was 75% vs 16.13% at week 12, 82.14% vs 22.58% at week 24, 89.29% vs 25.81% at week 36, and 96.43% vs 29.03% at week 48, respectively (P < 0.001). The rate of alanine aminotransferase normalization was significantly higher in the TDF than in the LAM plus ADV group at week 12 (75% vs 17.86%, P < 0.001), but not at week 24 (78.57% vs 54.84%, P = 0.097) or 48 (89.26% vs 67.74%, P = 0.062). Patients were hepatitis B e antigen (HBeAg) positive at baseline. There was no significant difference in HBeAg negativity between the TDF and LAM plus ADV groups at week 48 (4% vs 0%, P = 0.481). There were no drug-related adverse effects at week 48 in either group.

CONCLUSION: Switching to TDF monotherapy was superior to continuous add-on therapy in patients with LAM-resistant CHB with a suboptimal response to LAM plus ADV.

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.

HBV genotype B/C and response to lamivudine therapy: a systematic review

A number of nucleoside analogues such as lamivudine (LAM), actually used for the treatment of chronic hepatitis B, can suppress HBV DNA replication, improve transaminase level and liver histology, and enhance the rate of hepatitis B e antigen (HBeAg) clearance. The responses to LAM therapy involve HBeAg clearance and HBV DNA conversion of negative. However, the associations between HBV genotype B/C and response to LAM therapy remain ambiguous. The aim of this meta-analysis is to determine more precise estimations of the relationship. All the publications on the associations between HBV genotype B/C and response to LAM (HBeAg clearance and HBV DNA conversion of negative) through June 2013 were collected. Relative risk (RR) with 95% confidence intervals (95% CI) was calculated in fixed or random model, I² was calculated to examine heterogeneity, and funnel plots were plotted to examine small study effects with Stata 11 software. Overall, for HBeAg clearance and genotype B/C, the RR (95% CI) was 1.27 (0.94–1.71), while for HBV DNA conversion of negative and genotype B/C, the RR (95% CI) was 1.07 (0.98–1.17). HBV genotype B/C shows no significance associations with response to lamivudine therapy (HBeAg clearance and HBV DNA conversion of negative).