Novel mutation in YMDD motif and direct neighbourhood in a child with chronic HBV-infection and clinical lamivudine and adefovir resistance - a scholarly case

Role of GSPT1 and GSPT2 polymorphisms in different outcomes upon Hepatitis B virus infection and prognosis to lamivudine therapy

Purpose. ERF3, having been found expressing differently in liver tissues in our previous work, including eRF3a and eRF3b, which are structural homologs named GSPT1 and GSPT2 Recent studies have indicated that eRF3b involved in the development and proliferation of HepG2 cell, and eRF3a may be associated with tumor susceptibility. Based on this, we tested the effects of GSPT1 and GSPT2 single-nucleotide polymorphisms for all major Hepatitis B virus (HBV) outcomes and lamivudine (LAM) treatment in Han Chinese. Method. A total of 1649 samples were enrolled, and peripheral blood samples were collected in the present study. The single-nucleotide polymorphisms in the GSPT1 and GSPT2 region were genotyped using MALDI-TOF MS. Results. Our study demonstrated there was no obvious relevance of either GSPT1-rs33635 or GSPT2-rs974285 polymorphisms with HBV susceptibility, spontaneous recovery, and development of HBV-related diseases. However, we showed for the first time to our knowledge that GSPT1-rs33635C was a predictor for LAM therapy (viral response: odds ratio (OR) = 2.436, P=0.022; biochemical response: OR = 3.328, P=1.73 × 10^-4). Conclusions. These findings might provide potential implications for therapeutic guidance.

The rtA181S mutation of hepatitis B virus primarily confers resistance to adefovir dipivoxil

The study aimed to clarify clinical significance of hepatitis B virus (HBV) rtA181S mutation in Chinese HBV-infected patients. A total of 18 419 patients with chronic HBV infection from Beijing 302 Hospital were investigated. HBV complete reverse transcriptase region of polymerase was screened by direct sequencing, and the results were verified by clonal sequencing. Replication-competent mutant and wild-type HBV genomic amplicons were constructed and transfected into the HepG2 cells and cultured in the presence or absence of serially diluted nucleos(t)ide analogues. Intracellular HBV replicative intermediates were quantitated for calculating the 50% effective concentration of the drug (EC(50)). The rtA181S was detected in 98 patients with 12 kinds of mutational patterns. Genotype C and genotype B HBV infection occupied 91.8% and 8.2% in rtA181S-positive patients, in contrast to 84.6% and 15.4% in rtA181S-negative patients (P < 0.01). All rtA181S-positive patients had received nucleos(t)ide analogues. rtA181S was detected in multiple patients with virologic breakthrough. Phenotypic analysis of patient-derived viral strains showed that rtA181S, rtA181S+N236T, rtN236T and rtA181V strains had 68.5%, 49.9%, 71.4% and 66.2% of natural replication capacity of wild-type strain, and 3.7-fold, 9.8-fold, 7.9-fold and 5.6-fold increased EC(50) to adefovir dipivoxil (ADV). The rtA181S strain remained susceptible to lamivudine, entecavir and tenofovir, and ADV susceptibility was restored after the mutation was eliminated through site-directed mutagenesis. Rescue therapy with entecavir or combination therapy was effective in rtA181S-related ADV-refractory patients. The rtA181S mutation confers moderate resistance to ADV. It could be induced by either lamivudine or ADV and contribute ADV treatment failure.

Prevelance of common YMDD motif mutations in long term treated chronic HBV infections in a Turkish population

In the current study we aimed to show the common YMDD motif mutations in viral polymerase gene in chronic hepatitis B patients during lamivudine and adefovir therapy. Forty-one serum samples obtained from chronic hepatitis B patients (24 male, 17 female; age range: 34-68 years) were included in the study. HBV-DNA was extracted from the peripheral blood of the patients using an extraction kit (Invisorb, Instant Spin DNA/ RNA Virus Mini Kit, Germany). A line probe assay and direct sequencing analyses (INNO-LIPA HBV DR v2; INNOGENETICS N.V, Ghent, Belgium) were applied to determine target mutations of the viral polymerase gene in positive HBV-DNA samples. A total of 41 mutations located in 21 different codons were detected in the current results. In 17 (41.5%) patients various point mutations were detected leading to lamivudin, adefovir and/ or combined drug resistance. Wild polymerase gene profiles were detected in 24 (58.5%) HBV positive patients of the current cohort. Eight of the 17 samples (19.5%) having rtM204V/I/A missense transition and/or transversion point mutations and resistance to lamivudin. Six of the the mutated samples (14.6%) having rtL180M missense transversion mutation and resistance to combined adefovir and lamivudin. Three of the mutated samples (7.5%) having rtG215H by the double base substituation and resistance to adefovir. Three of the mutated samples (7.5%) having codon rtL181W due to the missense transversion point mutations and showed resistance to combined adefovir and lamivudin. Unreported novel point mutations were detected in the different codons of polymerase gene region in the current HBV positive cohort fromTurkish population. The current results provide evidence that rtL180M and rtM204V/I/A mutations of HBV-DNA may be associated with a poor antiviral response and HBV chronicity during conventional therapy in Turkish patients.

rtM204Q may serve as a novel lamivudine-resistance-associated mutation of hepatitis B virus

Background and Aims

Lamivudine (LAM) is still widely used for anti-HBV therapy in China. The study aimed to clarify whether a newly-found rtM204Q mutation from patients was associated with the drug resistance.

Methods

HBV complete reverse-transcriptase region was screened by direct sequencing and verified by clonal sequencing. Replication-competent plasmids containing patient-derived 1.1mer mutant or wild-type viral genome were constructed and transfected into HepG2 cells. After cultured with or without serially-diluted antiviral drugs, intracellular HBV replicative intermediates were quantitated for calculating the 50% effective concentration of drug (EC₅₀).

Results

A total of 12,000 serum samples of 9,830 patients with chronic HBV infection were screened. rtM204Q mutation was detected in seven LAM-refractory patients. By contrast, rtM204I/rtM204V mutations were detected in 2,502 patients' samples. The rtM204Q emerged either alone or in concomitance with rtM204I/rtM204V, and all were accompanied with virologic breakthrough in clinical course. Clonal sequencing verified that rtM204Q mutant was predominant in viral quasispecies of these samples. Phenotypic analysis showed that rtM204Q mutant had 89.9% of replication capacity and 76-fold increased LAM EC₅₀ of the concomitant wild-type strain. By contrast, rtM204I mutant in the sample had lower replication capacity and higher LAM resistance (46.3% and 1396-fold increased LAM EC₅₀ of the wild-type strain) compared to rtM204Q mutant. rtM204Q mutant was susceptible to adefovir dipivoxil (ADV) in vitro and ADV/ADV+LAM rescue therapy in clinic.

Conclusion

rtM204Q is suggested to be a novel LAM-resistance-associated mutation. It conferred a moderate resistance with higher competent natural replication capacity compared to rtM204I mutation.

Decreased antigenicity profiles of immune-escaped and drug-resistant hepatitis B surface antigen (HBsAg) double mutants

BACKGROUND

Selective pressure from either the immune response or the use of nucleoside analogs in antiviral therapy could be driving the emergence of HBV mutants. Because of the overlap of the open reading frame (ORF) S for the HBsAg and ORF P for viral polymerase, rtM204I and rtM204V mutations in the polymerase would produce sI195M and sW196S in the HBsAg. The combined effects of immune-escaped mutations (sT118M, sG145K, sG145R) and drug-resistant mutations (rtM204I, rtM204V) on the antigenicity profiles of HBsAg has not been widely explored.

METHODS

To determine the combined effects of immune-escaped and drug-resistant mutants on the antigenicity profiles of HBsAg, recombinant plasmids encoding HBsAg double mutants were constructed using site-directed mutagenesis. The supernatant from each plasmid transfection was analyzed for HBsAg in the western-blotting and five of the most commonly used commercial ELISA kits in China.

RESULTS

Western-blotting assay showed the successful expression of each HBsAg mutant. All five ELISA kits manifested similar avidity, which were demonstrated by the slope of the curves, for the sT118M mutant, and sT118M-rtM204I (sT118M-sI195M) and sT118M-rtM204V (sT118M-sW196S) double mutants, suggesting that drug-resistant YMDD mutants caused negligible losses in the antigenicity of immune-escaped sT118M HBsAg. In contrast, the presence of the rtM204I (sI195M) mutation, but not rtM204V (sW196S) in combination with the sG145K mutation significantly reduced the avidity of sG145K HBsAg. The rtM204I (sI195M) mutation also decreased the antigenicity profiles for sG145R HBsAg.

CONCLUSIONS

Drug-resistant mutations rtM204I (sI195M) and rtM204V (sW196S) caused significant reduction in antigenicity for the immune-escaped HBsAg mutants sG145K and sG145R, which may hamper HBV diagnosis and disease control from HBV blood-transfusion transmissions in China. The development of ELISA kits with a greater sensitivity for drug-resistant and immune-escaped HBsAg warrants further consideration.

Comparison of the 48-week efficacy between entecavir and adefovir in HBeAg-positive nucleos(t)ide-naïve Asian patients with chronic hepatitis B: a meta-analysis

Background

Although entacavir and adefovir were widely used in most Asian countries, there were few conclusions drawn from a meta-analysis for comparing the efficacy between entecavir and adefovir in nucleos(t)ide-naïve Asian patients with chronic hepatitis B (CHB). The aim of this study was to evaluate the 48-week efficacy between the two drugs in HBeAg-positive nucleos(t)ide-naïve Asian CHB patients with the method of Meta analysis, which was generally accepted by the international as the best evidence for evaluating the efficacy of drugs.

Methods

We searched all data documented in Pubmed, Embase, Wanfang Database and CNKI (China National Knowledge Infrastructure) before November 30, 2010. Heterogeneity was examined by Chi-square test, the relative risk calculated and forest plot drawn. Rates of undetected serum HBV DNA, serum alanine aminotransferase (ALT) normalization, HBeAg clearance and HBeAg seroconversion were analyzed. A total of 6 articles was included. Meta analysis showed that the rate of undetected serum HBV DNA (relative risk, 1.73; 95% confidence interval, 1.38-2.17; P < 0.00001) and that of serum ALT normalization (relative risk, 1.25; 95% confidence interval, 1.06-1.49; P = 0.009) in the entecavir group were higher than those in the adefovir group. However, no statistic significance existed between the two groups in the rate of HBeAg clearance (relative risk, 0.77; 95% confidence interval, 0.44-1.35; P = 0.36), or the rate of HBeAg seroconversion (relative risk, 0.74; 95% confidence interval, 0.28-1.94; P = 0.53).

Conclusions

Entecavir is superior to adefovir in decreasing serum HBV DNA and normalizing ALT but similar with adefovir in clearing HBeAg and encouraging HBeAg seroconversion for the HBeAg-positive nucleos(t)ide-naive Asian patients with chronic hepatitis B. Adefovir can be still used for first-line therapy in these patients.