Mutational patterns of hepatitis B virus genome and clinical outcomes after emergence of drug-resistant variants during lamivudine therapy: Analyses of the polymerase gene and full-length sequences

Adefovir for lamivudine-resistant hepatitis B

Adefovir, a nucleotide analog developed by John Martin, was a major breakthrough in the treatment of chronic Hepatitis B. Prior to adefovir, Hepatitis B treatment was limited to two therapeutic modalities, either interferon, which carried significant side effects and was efficacious in a minority of patients, or lamivudine which showed no durable effects with short-term use and a high rate of resistance with long-term use. Adefovir was found to be effective in suppressing viral replication and in resolving the hepatic inflammation associated with hepatitis B with only rare instances of resistance. In this article, we appreciate John Martin’s contribution to science and medicine as we review the landmark trials of adefovir that brought forth a new era of treatment of Hepatitis B.

Could resistant and escape variants of hepatitis B virus be a problem in the future?

Aim: Nucleos(t)ide analogs have a risk for the development of Polymerase gene mutations and they can cause compensatory mutations in the HBV surface gene. Alteration in the ‘a determinant’ of the s gene predispose for escape mutants. We aimed to evaluate primary, compensatory and escape mutations in chronic hepatitis B. Materials & methods: Two hundred nineteen specimens were obtained and HBV pol gene region was sequenced and amplified and HBV pol/s gene mutations were determined. Results: We detected primary mutation in 29.8% patients. Compensatory mutations were detected in 50.3%patients. Hepatitis B Immunoglobulin escape mutations, vaccine escape mutations, Hepatitis B diagnosis-escape and immunoselected amino acid substitutions were observed in 9.6%, 6.9%, 5.2% and 11.9% of patients, respectively. Antiviral drug-associated potential vaccine-escape mutants were detected in 17.9% patients. Conclusion: Therefore, epidemiological and demographical changes may be possible. Therefore, the typical HBsAg mutants and antiviral drug-associated potential vaccine-escape mutants should be monitored carefully.

Current concepts on immunopathogenesis of hepatitis B virus infection

Hepatitis B virus (HBV) infection is a leading cause of liver damage and hepatic inflammation. Upon infection, effective antiviral responses by CD8+ T cells, CD4+ T cells, Natural killer (NK) cells, and monocytes can lead to partial or complete eradication of the viral infection. To date, many studies have shown that the production of inhibitory cytokines such as Interleukin 10 (IL-10), Transforming growth factor beta (TGF-β), along with dysfunction of the dendritic cells (DCs), and the absence of efficient innate immune responses could lead to T cell exhaustion, development of persistent infection, and inability to eradicate the viral infection from liver. Understanding the immunopathogenesis of the virus could be useful in providing further insights toward novel strategies in the eradication of HBV infection.

Evidence of susceptibility to lamivudine-based HAART and genetic stability of hepatitis B virus (HBV) in HIV co-infected patients: A South African longitudinal HBV whole genome study

BACKGROUND

Reports on the concomitant impact of HIV co-infection and long term highly active anti-retroviral therapy (HAART) on the genetic stability and molecular evolution of HBV are limited in sub-Saharan Africa.

MATERIALS AND METHODS

This retrospective study investigated the molecular evolution of chronic HBV in HIV co-infected patients on lamivudine (3TC)-based HAART over a 5year period. Four HIV co-infected patients, consecutively recruited and followed-up, were screened for hepatitis B serological markers, and their viral loads determined. The HBV genome was amplified from longitudinal samples and characterized by Bayesian inference, mutational analysis, and identification of immune selection pressure.

RESULTS

All patients exhibited persistent chronic HBV infection at baseline, as well as over the course of follow-up despite exposure to 3TC-based HAART. The polymerase gene in all isolates was relatively variable prior to HAART initiation at baseline and during the course of follow-up, although primary drug resistance mutations were not detected. All but one patient were infected with HBV subgenotype A1. The divergence rates between baseline and the last follow-up sequences ranged from 0 to 2.0×10(-3) substitutions per site per year (s/s/y). Positive selection pressure was evident within the surface and core genes.

CONCLUSION

Despite persistent HBV infection in the HIV co-infected patients exposed to long term 3TC-based HAART, the molecular evolution of HBV over a 5year period was unremarkable. In addition, HBV exhibited minimal genetic variability overtime.

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.

Complete genome analysis of hepatitis B virus in human immunodeficiency virus infected and uninfected South Africans

Hepatitis B virus (HBV) and human immunodeficiency virus (HIV) infections are highly endemic in South Africa. Data on the complete genome sequences of HBV in HIV-positive patients in South Africa are scanty. This study characterized the complete HBV genome isolated from both HIV-positive and negative patients at the Dr George Mukhari Academic Hospital (DGMAH), Pretoria. Serum samples from nine (five HIV-positive and four HIV-negative) patients attending the DGMAH from 2007 to 2011 were serologically tested, amplified, and sequenced for complete genome. Phylogenetic tree was constructed using MEGA6.0. Mutations were analyzed by comparing the sequences with genotype-matched GenBank references. Eight patients were HBsAg positive, with only one from the HIV positive group being negative. Phylogenetic analysis of the complete genome sequences classified them into five genotypes; A1 (n = 4), A2 (n = 1), C1 (n = 2), D1 (n = 1), and D3 (n = 1). Deletions up to 35 nucleotides in length were identified in this study. No drug resistance mutations were identified in the P ORF, while the L217R mutation was identified in one subgenotype A2 sequence. The double (A1762T/G1764A) and triple (T1753C/A1762T/G1764A) mutations in the Basal core promoter were identified in four and two sequences, respectively. In the core region, mutation G1888A was identified in four of the subgenotype A1 sequences. In conclusion, this study has added to the limited South African data on HBV genotypes and mutations in HBV/HIV co-infected and HBV mono-infected patients, based on complete HBV genome analysis. Subgenotype A1 was predominant, and no drug-resistant mutants were detected in the study. J. Med. Virol. 88:1560-1566, 2016. © 2016 Wiley Periodicals, Inc.

Universal Primers for Detection and Sequencing of Hepatitis B Virus Genomes across Genotypes A to G

Hepatitis B virus (HBV) has been divided into 10 genotypes, A to J, based on an 8% nucleotide sequence divergence between genotypes. The conventional practice of using a single set of primers to amplify a near-complete HBV genome is hampered by its low analytical sensitivity. The current practice of using overlapping conserved primer sets to amplify a complete HBV genome in a clinical sample is limited by the lack of pan-primers to detect all HBV genotypes. In this study, we designed six highly conserved, overlapping primer sets to cover the complete HBV genome. We based our design on the sequences of 5,154 HBV genomes of genotypes A to I downloaded from the GenBank nucleotide database. These primer sets were tested on 126 plasma samples from Malaysia, containing genotypes A to D and with viral loads ranging from 20 to >79,780,000 IU/ml. The overall success rates for PCR amplification and sequencing were >96% and >94%, respectively. Similarly, there was 100% amplification and sequencing success when the primer sets were tested on an HBV reference panel of genotypes A to G. Thus, we have established primer sets that gave a high analytical sensitivity for PCR-based detection of HBV and a high rate of sequencing success for HBV genomes in most of the viral genotypes, if not all, without prior known sequence data for the particular genotype/genome.

Prospective long-term study of hepatitis B virus reactivation in patients with hematologic malignancy

BACKGROUND AND AIM

To elucidate the clinical characteristics of hepatitis B virus reactivation (HBV-R), we performed a prospective long-term study of patients with hematologic malignancy, including both hepatitis B virus (HBV) carriers and those with resolved HBV infection.

METHODS

Twenty-one patients with hematopoietic stem-cell transplants (HSCT) and 36 patients given rituximab-based chemotherapy were enrolled. Entecavir was administered prophylactically to eight patients with HBV surface antigen (HBsAg). HBV-DNA was measured every month in 49 patients with resolved HBV infection, and preemptive therapy was given to eight patients with HBV-R.

RESULTS

HBV-R developed in five (26%) of 19 patients with HSCT and three (10%) of 30 patients given rituximab-based chemotherapy. HBV-R occurred a median of 3 months (range: 2-10) after the end of rituximab-based chemotherapy and 22 months (range: 9-36) after HSCT. HBV-R did not develop in patients with an antibodies against HBsAg (anti-HBs) titer exceeding 200 mIU/mL at baseline. Mutations in the "a" determinant region with amino acid replacement were detected in four of the eight patients with HBV-R. Preemptive therapy prevented severe hepatitis related to HBV-R. Entecavir treatment was stopped in four patients with HBV-R. Since the withdrawal of entecavir, HBV-DNA has not been detected in two patients persistently positive for anti-HBs. No patient had fatal hepatitis.

CONCLUSIONS

Proper management of patients with HBsAg or resolved HBV infection prevented fatal hepatitis related to HBV-R in patients who received immunosuppressive or cytotoxic therapy. Entecavir could be safely discontinued in patients with HBV-R who had acquired anti-HBs.

Analysis of reverse transcriptase gene mutations in the hepatitis B virus at a university hospital in Korea

BACKGROUND

Most mutations in the reverse transcriptase (RT) gene of the hepatitis B virus (HBV) are related to resistance to antiviral agents. Cross-sectional studies on the mutations of this gene are rare. Thus, we analyzed the mutation patterns of RT genes and their biochemical parameters.

METHODS

From 2009 to 2012, 301 blood specimens from patients with chronic hepatitis B at Daegu Catholic University Medical Center were retrospectively analyzed for the RT gene sequence of HBV, ALT, hepatitis B e antigen (HBeAg), and HBV DNA. The mutation patterns of the RT gene were compared with the biochemical parameters.

RESULTS

Of the 301 patients, 100 (33.2%) had no RT gene mutations. The remaining showed the following mutation patterns: rtM204I/V (50.2%), rtL180M (39.2%), and rtA181T/V (19.6%). Combined mutations were found in 146 cases (48.5%). Of these, the combination of amino acid changes at rt180+rt204 (49.3%) was most frequently detected, followed by rt181+rt236 (11.0%) and rt173+rt180+rt204 (9.6%). In the mutated group, HBV DNA and HBeAg positive rates were significantly higher (P<0.05 for both). Phenotypic analysis showed that lamivudine resistance was most frequently detected (34.6%), followed by adefovir resistance (15.6%). Multidrug resistance was detected in 48 cases (15.9%). The adefovir-resistant group had a higher proportion of cases with HBV loads greater than 2,000 IU/mL.

CONCLUSIONS

We found correlations between the mutation status of the RT domain and biochemical parameters such as HBV DNA and HBeAg positive rate. The presence of RT gene mutations could therefore be utilized to predict clinical status.

Ultrasensitive amplification refractory mutation system real-time PCR (ARMS RT-PCR) assay for detection of minority hepatitis B virus-resistant strains in the era of personalized medicine

Resistance to antiviral treatment for chronic hepatitis B virus (HBV) has been associated with mutations in the HBV polymerase region. This study aimed at developing an ultrasensitive method for quantifying viral populations with all major HBV resistance-associated mutations, combining the amplification refractory mutation system real-time PCR (ARMS RT-PCR) with a molecular beacon using a LightCycler. The discriminatory ability of this method, the ARMS RT-PCR with molecular beacon assay, was 0.01 to 0.25% for the different HBV resistance-associated mutations, as determined by laboratory-synthesized wild-type (WT) and mutant (Mut) target sequences. The assay showed 100% sensitivity for the detection of mutant variants A181V, T184A, and N236T in samples from 41 chronically HBV-infected patients under antiviral therapy who had developed resistance-associated mutations detected by direct PCR Sanger sequencing. The ratio of mutant to wild-type viral populations (the Mut/WT ratio) was >1% in 38 (63.3%) of 60 samples from chronically HBV-infected nucleos(t)ide analogue-naive patients; combinations of mutations were also detected in half of these samples. The ARMS RT-PCR with molecular beacon assay achieved high sensitivity and discriminatory ability compared to the gold standard of direct PCR Sanger sequencing in identifying resistant viral populations in chronically HBV-infected patients receiving antiviral therapy. Apart from the dominant clones, other quasispecies were also quantified. In samples from chronically HBV-infected nucleos(t)ide analogue-naive patients, the assay proved to be a useful tool in detecting minor variant populations before the initiation of the treatment. These observations need further evaluation with prospective studies before they can be implemented in daily practice.

Antiviral therapy against chronic hepatitis B in Brazil: high rates of lamivudine resistance mutations and correlation with HBV genotypes

The effectiveness of antiviral treatments of chronic hepatitis B has been poorly studied in Brazil. Here, hepatitis B virus (HBV) DNA positivity, drug resistance mutations and their association with HBV genotypes were evaluated in chronically HBV-infected patients under different drug regimens in Brazil. The study involved 129 patients under interferon or nucleos(t)ide analogue therapy for a median treatment time of 12 months. One hundred and five (81%) of these patients were treated with lamivudine (LAM), either in monotherapy or in combination with newer drugs, such as entecavir (ETV) or tenofovir (TDF). High (37.5-100%) rates of HBV DNA positivity were observed with all but one drug regimen (LAM + ETV). However, patients that were treated with ETV alone, TDF alone or with LAM combination therapies had a mean viral load that was 3-4 log lower than patients treated with LAM monotherapy. Of the patients treated with LAM, 47% developed resistance mutations. HBV genotypes A (59.1%), D (30.3%) and F (9.1%) were found. There was no association between the presence of LAM resistance mutations and genotypes, HBeAg status or treatment duration. Nevertheless, the rtM204V mutation was observed more frequently (12/13, 92%) in genotype A than in the others (p = 0.023). Six out of nine isolates that contained the rtM204I mutation belonged to genotype D and half of them displayed a single mutation. Genotype D isolates with the rtM204V variant preferentially displayed a triple mutation, while genotype A preferentially displayed a double mutation (p = 0.04).

In vitro activity of cepharanthine hydrochloride against clinical wild-type and lamivudine-resistant hepatitis B virus isolates

Hepatitis B virus (HBV) infection causes major public health problems worldwide. The clinical limitation of current antiviral drugs for HBV, such as lamivudine, is the emergence of drug-resistant viral strains during prolonged antiviral therapy. Cepharanthine hydrochloride (CH), a natural alkaloid-derived compound, has been reported to possess potent activity against various viruses. The present study was performed to evaluate the in vitro activity of CH against clinical wild-type and lamivudine-resistant HBV isolates in transiently transfected cells. HBV DNA was extracted from serum samples collected both before lamivudine therapy and at the time of viral breakthrough and was amplified by polymerase chain reaction (PCR). The amplicons were cloned into a novel expression vector, pHY106, which can initiate the intracellular HBV replication cycle after cell transfection. Following transfection of the cloned amplicon into HepG2 cells, a drug susceptibility assay was performed. The level of viral antigen, HBeAg, was determined by enzyme-linked immunosorbent assay (ELISA). Quantitative real-time PCR (Q-PCR) was used for determining the amount of intracellular HBV DNA. Heat stress cognate 70 (Hsc70), a host protein required for HBV replication, was also analyzed by reverse transcription PCR (RT-PCR) to explore the possible antiviral mechanism of CH. The results showed that CH inhibited replication and HBeAg production by either wild-type or lamivudine-resistant HBV clinical isolates in a dose-dependent manner. The Hsc70 mRNA was also downregulated significantly. In conclusion, CH is active against both wild-type and lamivudine-resistant HBV clinical isolates, and its activity may be associated with its inhibition of host Hsc70.

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

BACKGROUND

Lamivudine (LMV), as the preferred oral drug for use in treatment of HBV, always results in development of resistance mutations after long-term treatment. In this study we investigated chronic hepatitis B (CHB) patients in southern China to determine whether different HBV genotypes affect the incidence of LMV resistance mutations.

MATERIAL/METHODS

The study recruited 185 CHB patients living in southern China. Enzyme-linked immunosorbent assay was used to test for HBV serological markers, and HBV DNA was quantified by real-time PCR. Sequencing was performed to detect HBV genotypes and mutations.

RESULTS

There were 49.19% (91/185) CHB patients with HBV resistant to LMV. Only 2 genotypes were found: B and C; 62.16% (115/185) of patients were infected with genotype B HBV and 37.84% (70/185) of patients were infected with genotype C HBV. The incidence rate of LMV resistance was not significantly different between genotype B and C (49.57% vs. 48.57%, P>0.05). For the mean age and sex ratio, no significant difference was found. The pattern of rtM204I alone was predominantly observed (36.26%, 33/91), followed by rtM204V+rtL180M (23.08%, 21/91). The overall incidence rate of rtM204I mutation in genotype B (45.61%, 26/57) was more frequent than that in genotype C (20.59%, 7/34) (45.61% vs. 20.59%, P<0.05), but the incidence rate of other mutation patterns was not significantly different between genotypes B and C.

CONCLUSIONS

Our results emphasize that a LMV resistance test before treatment is of great importance in rational and optimal CHB therapy.

Analysis of hepatitis B virus X gene (HBx) mutants in tissues of patients suffered from hepatocellular carcinoma in China

Hepatitis B virus (HBV) X (HBx) gene multi-site mutations are a frequent event in the clinical hepatocellular carcinoma (HCC) tissues. It has been reported that the mutation of the HBx plays a crucial role in the development of HBV-related HCC. To identify the novel mutations of HBx in the HCC tissues, we examined and analyzed the sequences of HBx gene in 60 cases of HCC tumor tissues and paratumor tissues from China by polymerase chain reaction (PCR). The mutation patterns of HBx were analyzed by comparing the tumor tissues with non-tumor tissues. The data showed that 44 cases of tissues out of 60 patients were HBV-positive. Our results showed that the mutations at amino acid 30, 88, 144 from tumor samples and at amino acid 31, 43, 87, 94 from non-tumor samples were highly frequent events. Interestingly, we found that a novel type of HBx linked-mutations, such as at aa L30F/S144A, was 29.5% (13/44) positive in the tumor tissues. However, the role of HBx gene mutations at aa L30F/S144A relative to wild type HBx gene is unclear in hepatocarcinogenesis. The novel HBx linked-mutations may be significant in the development of HCC.

Identification of hepatitis B virus rtS117F substitution as a compensatory mutation for rtM204I during lamivudine therapy

OBJECTIVES

The replication defect of hepatitis B virus (HBV) lamivudine-resistant mutants can be restored by the development of compensatory mutations. Such mutations have long been recognized for the rtM204V mutant, while little is known about any compensatory mutation specific to the rtM204I mutant. The aim of this study was to search for previously unrecognized compensatory mutations following development of lamivudine-resistant mutants.

METHODS

Of 83 lamivudine-resistant patients, 49 and 34 patients harboured the rtM204I and rtM204V mutations, respectively. Serial serum samples obtained during the therapeutic course were submitted to sequence analysis. Site-directed mutagenesis experiments were performed to examine the functions of the identified associated mutations.

RESULTS

Of the 49 patients carrying the rtM204I mutation, 5 subsequently developed an rtS117F substitution during the follow-up, whereas 4 harboured an rtN124D substitution prior to the development of the rtM204I mutation. Emergence of the rtS117F mutation was associated with an increase in hepatitis activity, whereas prior existence of the rtN124D mutation was associated with decompensated liver function upon development of the rtM204I mutation. Site-directed mutagenesis experiments showed that the rtS117F mutation by itself did not confer lamivudine resistance but it compensated for replication deficiency of the rtM204I mutant in HepG2 and Mahlavu cells. Additionally, virion and hepatitis B surface antigen secretion of the rtS117F mutant was significantly impaired.

CONCLUSIONS

The rtS117F substitution served as a compensatory mutation for rtM204I. Emergence of the rtS117F mutation in lamivudine-resistant patients carrying rtM204I was associated with increased hepatitis activities. Prior existence of the rtN124D substitution was associated with liver decompensation upon development of the rtM204I mutation.

Evolutionary pattern of full hepatitis B virus genome during sequential nucleos(t)ide analog therapy

The evolutionary and mutational pattern of full hepatitis B virus (HBV) quasispecies during sequential nucleos(t)ide analog (NUC) therapy remains unclear. In this study, full-length HBV clones were generated from serial serum samples of five chronic hepatitis B patients who received sequential NUC therapies (treated patients) and two untreated patients with acute flares. The evolutionary and mutational patterns of full HBV quasispecies were studied. In the three treated patients who received lamivudine as initial antiviral therapy, nucleotide polymorphism and nonsynonymous divergence all decreased at lamivudine breakthrough but increased after rescue therapies. Conversely, two other treated patients showed a distinct change in divergence during adefovir-telbivudine sequential therapies. Untreated subjects exhibited increased polymorphism and divergence in the preC/C region at ALT flare. Four of the treated patients presented amino acid changes in the "a" determinant during NUC therapy. All of the treated subjects showed amino acid changes within the known T-cell or B-cell epitopes in the surface or core antigen, most of which were accompanied by mutations in reverse transcriptase (RT) region. Co-variations in the core promoter, the preC region and in the known epitopes of the preS gene accompanied by RT mutations, were common. In untreated patients, most of these co-variations located in the preC/C gene. In conclusion, the distribution of genetic variability of HBV shows remarkably different patterns between the treated and untreated subjects and the quasispecies divergence of different regions of HBV may vary remarkably even within a single host.

Mutation pattern of lamivudine resistance in relation to hepatitis B genotypes: hepatitis B genotypes differ in their lamivudine resistance associated mutation pattern

Little is known about differences between individual hepatitis B genotypes and mutation patterns associated with lamivudine resistance. This study analyses the lamivudine-associated mutation pattern in relation to the four major HBV genotypes A-D. The PubMed database was screened for keywords "HBV OR Hepatitis B," "YMDD," "genotype," and "lamivudine"; all identified publications published till June 2009 were analyzed for differences in mutation pattern. To confirm the literature-based findings the databases of two reference laboratories in Tübingen (Germany), and Melbourne (Australia) were analyzed. Twenty-nine studies were identified reporting 827 patients with known hepatitis B genotype who underwent lamivudine treatment and developed resistance mutations. The literature data revealed that genotype A favors the rtM204V mutation unlike the other major genotypes (P<0.001), which corresponds to a significant difference in the mutation pattern of genotypes endemic in Asian countries and those found in the rest of the world. These significant findings of the literature-review could be reproduced in the analysis of the databases from Tübingen and Melbourne. Furthermore, the rtL180M mutation is significantly connected to the rtM204V mutation in genotypes A, B, and C, respectively. It is concluded that there is proof that HBV genotypes differ in their mutation pattern of lamivudine resistance. Future studies will need to evaluate whether this will translate into genotype-specific differences in resistance emergence on either entecavir or telbivudine as these antivirals differ in their mutation profile, rtM204V for entecavir and rtM204I for telbivudine.

Monitoring of therapy in patients with chronic hepatitis B virus

OBJECTIVE

The aims of this study were to evaluate therapy with lamivudine (LAM) and adefovir dipivoxil (ADV) monotherapy in chronic hepatitis B virus (HBV)-infected patients with frequent measurements of DNA levels, to characterize HBV genotypes, and to determine the emergence of nucleos(t)ide analogue mutants before and during the therapy by direct-sequencing the reverse transcriptase region and by INNO-LiPA HBV DR v3.

MATERIALS AND METHODS

A total of 15 chronic HBV patients were analysed: 11 were treated with ADV and four were treated with LAM.

RESULTS

Viral genotype was determined, showing the presence of genotype D (73%) in 11 patients and genotype A (27%) in four patients. In the viral response to treatment, three patients developed substitutions at rtM204I associated with LAM resistance and one of these patients presented rtM204V/I plus rtL180M mutation. In contrast, of the 11 patients treated with ADV, three patients developed mutations (rtN236T; rtA181V; rtA181V plus rtN236T). With regard to this case, the same results were observed by INNO-LiPA HBV DR v3 and direct sequencing, but by direct sequencing we detected an extra mutation rtQ215S that was present in two patients: one patient who was on treatment with LAM had an rtQ215S mutation in addition to an rtM204I, and the second patient treated with ADV had rtA181V.

CONCLUSION

Direct sequence analysis is an essential tool to optimize therapeutic management of HBV chronic infection in clinical practice to choose the appropriate nucleos(t)ide analogues and to detect extra mutations that are not included in the commercial kit.

Anti-hepatitis B virus treatment guided by long-term virus kinetics stepwise tracing

BACKGROUND AND AIMS

Biphasic modeling of viral kinetics provided valuable information to rapidly assess potential antiviral regimens during the beginning of therapy, but has not been performed over the long term.

METHODS

In 11 chronic hepatitis B patients with lamivudine treated per day, the model with delay time was applied to examine phase transition and analyze viral kinetics parameters.

RESULTS

Viral decay conformed to a biphasic mode during the first 4 weeks, with the complex profile appeared in the later period. Lamivudine treatment resulted in a mean log hepatitis B virus (HBV)-DNA decline of 1.77 +/- 0.55 after 4 weeks and 3.79 +/- 1.70 log after 24 weeks. The median effectiveness of blocking viral replication was 96% (range, 89-99%). The median rate of free virus clearance and infected cell loss was 1.1/day and 0.03/day, respectively. Through phase transition determination and stepwise modeling process, viral kinetics were evaluated for complex decay profile during long-term therapy. Moreover, with the abnormal kinetics tracked, an occasion of add-on combined therapy was developed to treat patients with emerging virus mutants.

CONCLUSION

The present study using mathematical modeling of viral decay may be a useful approach to evaluate optimal individualized therapy for HBV infection in a continuous long-term manner.

Association of lamivudine-resistant mutational patterns with the antiviral effect of adefovir in patients with chronic hepatitis B

Adefovir has a potent antiviral activity as a rescue treatment against lamivudine-resistant strains. The aim of this study was to assess the patterns of lamivudine-resistant mutations and their influence on the virologic response to adefovir rescue therapy in patients with lamivudine-resistant chronic hepatitis B. Sixty-seven patients with lamivudine-resistant chronic hepatitis B were treated with adefovir monotherapy. Baseline blood samples were analyzed for lamivudine-resistant mutations via restriction fragment mass polymorphism. Virologic responses, ALT normalization and loss of HBeAg were assessed. Serum HBV DNA levels were measured using real-time PCR at baseline and 24 weeks of adefovir therapy. Of the 67 patients with chronic hepatitis B, 65 patients (97%) had lamivudine-resistant mutations in the YMDD motif [27 (41%) rtM204I, 22 (34%) rtM204V, and 16 (25%) rtM204I/V]. In addition to the YMDD mutations, the rtL180M, rtL80I, and rtV173L mutations were also present in 78%, 43%, and 11% of patients, respectively. The rtM204V mutation always accompanied rtL180M, and rtL80I was always observed in conjunction with rtM204I. Decrease in mean serum HBV did not differ between patients carrying the rtM204I versus rtM204V mutant at week 24 (-3.3 vs. -3.3 log(10) copies/ml, respectively; P = 0.303). The presence of the rtL180M, rtL80I, and rtV173L did not significantly affect viral load reduction during adefovir administration. These results demonstrate that the rtL80I mutant is co-selected with rtM204I as a compensatory mutation in the same manner as rtL180M with rtM204V, and that adefovir shows similar antiviral efficacy against all of the evaluated patterns of lamivudine-resistant HBV mutations.

Optimal duration of additional therapy after biochemical and virological responses to lamivudine in patients with HBeAg-negative chronic hepatitis B: a randomized trial

AIM

The endpoint of treatment with nucleoside analogs remains unclear for patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B. We report the results of a randomized trial to determine the optimal duration of additional therapy after response to lamivudine in HBeAg-negative patients.

METHODS

Twenty-two patients with HBeAg-negative chronic hepatitis B who exhibited biochemical and virological responses to lamivudine were enrolled. When patients responded to treatment, they were randomly assigned to receive 12 more months of therapy (Group A, 11 patients) or 24 more months of therapy (Group B, 11 patients).

RESULTS

The baseline characteristics of the patients were similar in the two groups. Biochemical and virological responses were obtained in all patients within 6 months. Drug resistance developed in one patient in Group A during month 7 of additional therapy, and in five patients in Group B from months 13-23 of additional therapy. Ten patients in Group A and six in Group B completed the protocol and were included in analysis. Eight of the 10 patients in Group A experienced relapse between months 2 and 14 after the discontinuation of therapy, while three of the six patients in Group B experienced relapse between months 2 and 24. There was no difference in cumulative relapse rate between the groups (P = 0.275).

CONCLUSION

Additional therapy with lamivudine for longer than 12 months after biochemical and virological responses in patients with HBeAg-negative chronic hepatitis B could increase the risk of drug resistance, but did not reduce the rate of relapse.