Do we need to determine viral genotype in treating chronic hepatitis B?

Molecular epidemiology of hepatitis B virus genotypes in blood donors in Islamabad, Pakistan

BACKGROUND:

Hepatitis B virus (HBV) is a major causative agent of early, severe and prolonged liver infection that subsequently leads to cirrhosis of liver and hepatocellular carcinoma. The aim of this study was to evaluate the molecular epidemiology of hepatitis B virus (HBV) genotypes and comparison of serological assay performance versus polymerase chain reaction (PCR) in HBV screening.

METHODS:

Blood samples of 8517 healthy blood donors were collected during the period of January to June 2017 from Blood Bank of Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad. Samples were screened for HBsAg assay using technique of chemiluminescence immunoassay. PCR of positive samples was carried out using already reported genotype-specific primers by Naito et al. (2001). The results were confirmed by visualizing genotype bands.

RESULTS:

The study confirmed the presence of HBV in 2.5% of blood donors, and PCR confirmed the presence of HBV-DNA in 92 samples. The genotyping was done by PCR using type-specific primer sequences. PCR was dogged to check six genotypes, i.e., A, B, C, D, E, and F. The results of this study show high levels of Genotype D is this region, i.e., 52.17% with less dominating Genotype C, which is 16.30% with decreasing ratio of Genotype E (14.13%), Genotype A and B (9.78%), and mixed D + E (2.17%). The presence of coinfection is found at lowest rate. Due to the high percentage of HBV/D, it is concluded that D genotype is common in our population.

CONCLUSION:

The most prevalent HBV genotype in ICT region was genotype D, which is responsible for liver cirrhosis and hepatocellular carcinoma. Efficacy of drugs varies with variation in genotypes of hepatitis B virus and also with geographical distribution.

Original Research: Analysis of hepatic microRNA alterations in response to hepatitis B virus infection and pegylated interferon alpha-2a treatment

Interferons play important roles in defense mechanisms against viral infection, and thus interferon therapy has been a standard treatment in chronic hepatitis B patients. Interferons signaling pathways promote interferon-inducible genes including microRNAs. In this research, we aimed to determine microRNAs expression profiles in vitro and in vivo For in vitro model, Huh7 cells were transfected with or without hepatitis B virus plasmid for 6 h, and then treated with 100 ng of pegylated-interferon alpha-2a for 24 h. In vivo, we defined microRNAs expression profiles in pair-liver tissues of chronic hepatitis B patients in comparison between before and after treatment of pegylated-interferon alpha-2a for 48 weeks. Cellular small RNAs were extracted followed by library preparation. To determine microRNAs expression profiles, the next-generation sequencing was carried out on MiSeq platform (Illumina®). In vitro analysis demonstrated that microRNAs can be classified into up-regulated and down-regulated microRNAs in response to hepatitis B virus, interferon, and combination of hepatitis B virus and interferon. Moreover, in vivo analysis revealed microRNAs profiles in non-responders, responders without hepatitis B surface antigen clearance, and responders with hepatitis B surface antigen clearance. The target genes of the candidate microRNAs were determined in terms of roles in cellular pathways and immune response, which might be related to treatment in chronic hepatitis B patients. Results revealed that two down-regulated microRNAs including miR-185-5p and miR-186-5p were correlated in both in vitro and in vivo studies. These two microRNAs might be represented as specific hepatic microRNAs responding to hepatitis B virus and pegylated-interferon alpha-2a treatment, which may remarkable and attractive for further study involving in the association of their target genes and prediction of pegylated-interferon alpha-2a response. Interestingly, microRNAs expression patterns might be useful for understanding the response mechanism and serve as biomarkers for prediction of pegylated-interferon alpha-2a treatment response in patients with chronic hepatitis B.

Clinical relevance of hepatitis B virus variants

The hepatitis B virus (HBV) is a global public health problem with more than 240 million people chronically infected worldwide, who are at risk for end-stage liver disease and hepatocellular carcinoma. There are an estimated 600000 deaths annually from complications of HBV-related liver disease. Antiviral therapy with nucleos/tide analogs (NA) targeting the HBV polymerase (P) can inhibit disease progression by long-term suppression of HBV replication. However, treatment may fail with first generation NA therapy due to the emergence of drug-resistant mutants, as well as incomplete medication adherence. The HBV replicates via an error-prone reverse transcriptase leading to quasispecies. Due to overlapping open reading frames mutations within the HBV P can cause concomitant changes in the HBV surface gene (S) and vice versa. HBV quasispecies diversity is associated with response to antiviral therapy, disease severity and long-term clinical outcomes. Specific mutants have been associated with antiviral drug resistance, immune escape, liver fibrosis development and tumorgenesis. An understanding of HBV variants and their clinical relevance may be important for monitoring chronic hepatitis B disease progression and treatment response. In this review, we will discuss HBV molecular virology, mechanism of variant development, and their potential clinical impact.

Genetic Diversity of the Hepatitis B Virus Strains in Cuba: Absence of West-African Genotypes despite the Transatlantic Slave Trade

Cuba is an HBsAg low-prevalence country with a high coverage of anti-hepatitis B vaccine. Its population is essentially the result of the population mix of Spanish descendants and former African slaves. Information about genetic characteristics of hepatitis B virus (HBV) strains circulating in the country is scarce. The HBV genotypes/subgenotypes, serotypes, mixed infections, and S gene mutations of 172 Cuban HBsAg and HBV-DNA positive patients were determined by direct sequencing and phylogenetic analysis. Phylogenetic analysis of HBV S gene sequences showed a predominance of genotype A (92.4%), subgenotype A2 (84.9%) and A1 (7.6%). Genotype D (7.0%) and subgenotype C1 (0.6%) were also detected but typical (sub)genotypes of contemporary West-Africa (E, A3) were conspicuously absent. All genotype A, D, and C strains exhibited sequence characteristics of the adw2, ayw2, and adrq serotypes, respectively. Thirty-three (19.1%) patients showed single, double, or multiple point mutations inside the Major Hydrophilic domain associated with vaccine escape; eighteen (10.5%) patients had mutations in the T-cell epitope (amino acids 28-51), and there were another 111 point mutations downstream of the S gene. One patient had an HBV A1/A2 mixed infection. This first genetic study of Cuban HBV viruses revealed only strains that were interspersed with strains from particularly Europe, America, and Asia. The absence of genotype E supports previous hypotheses about an only recent introduction of this genotype into the general population in Africa. The presence of well-known vaccine escape (3.5%) and viral resistance mutants (2.9%) warrants strain surveillance to guide vaccination and treatment strategies.

Retrospective study of the prevalence and clinical significance of hepatitis B virus precore and basal core promoter variants

BACKGROUND

Hepatitis B virus (HBV) precore (PC) and basal core promoter (BCP) variants are well known; however, their prevalence in North America is unclear, especially among hepatitis B e antigen-negative patients.

OBJECTIVE

To investigate the prevalence of PC⁄BCP mutations and their clinical significance.

METHODS

One hundred twenty-eight patients positive for both hepatitis B surface antigen and hepatitis B e antibody were selected, and PC⁄BCP mutations were identified using a line probe assay. The subjects' charts were reviewed for race⁄ethnicity, HBV genotype, HBV viral load, sex, liver enzyme levels, imaging and biopsy results up to 10 years before the study.

RESULTS

The prevalence of PC and BCP variants were 47.6% and 62.5%, respectively. Older age was associated with aspartate aminotransferase-to-platelet index ratio (APRI) ≥0.7 (P=0.011) and abnormal imaging⁄biopsy results (P=0.0008). Although the presence of BCP variant(s) was associated with APRI ≥0.7 (P=0.029), it was not associated with abnormal imaging⁄biopsy results. The combination of age ≥50 years and the presence of BCP variant(s) was associated with abnormal imaging⁄biopsy results, suggestive of either cirrhosis or hepatocellular carcinoma (not observed with PC mutation). Neither sex or genotype, or median HBV viral load showed significant influence on any of these outcomes.

CONCLUSIONS

The present study suggests that the prevalence of PC and BCP mutations are higher than what has been previously reported. One potential explanation would be increased immigration in the past decade. Considering the potential public health and clinical implications of these variants, long-term multicentre and prospective studies could further unravel the uncertainty around these variants.

HBV genotype changes in entecavir-naïve chronic hepatitis B patients

AIM: To investigate the hepatitis B virus (HBV) genotype changes in entecavir (ETV)-naïve chronic hepatitis B (CHB) patients.

METHODS: Thirty-eight ETV-naïve CHB patients treated and followed at our hospital were retrospectively analyzed. Blood serum samples were collected at months 0, 1, 3, 6, 9, 12, and 24. HBV DNA was retrieved from those samples and subjected to amplification, sequencing, and genotyping.

RESULTS: A total of 100 serum samples were collected from 38 CHB patients included in this study. Among all detected serum samples, genotype B was detected in 80 cases, genotype C was detected in 20 cases, and genotypes A, D, E, F, G, H, I and J were not detected in those samples. HBV genotype was detected to switch among 11 ETV-naïve patients. Six patients changed from genotype C to genotype B, and 5 cases switched from genotype B to genotype C. Of 14 patients who had reserved baseline serum, HBV genotype changed in 5 patients, including 2 patients switching from genotype B to genotype C and 3 patients from genotype C to genotype B. Phylogenetic analysis showed that the genetic distance of genetic sequences changed between baseline and the time point when HBV genotype changed.

CONCLUSION: HBV genotype may change in ETV-naive CHB patients, and the mechanisms require further investigation.

Hepatitis B virus drug resistance tools: one sequence, two predictions

Drug resistance testing, genotype analysis, and the determination of immune and vaccine escape variants support personalized antiviral treatment for hepatitis B patients. As phenotypic drug resistance testing for hepatitis B virus (HBV) is especially labor-intensive, due to the lack of simple cell culture systems, genotypic methods play a very pronounced role. The genetic structure of HBV allows the simultaneous analysis of two different genes by examination of a single region in the genome of HBV. Nevertheless, the overlapping open reading frames of the hepatitis B surface antigen (HBsAg) and the reverse transcriptase (RT) have to be interpreted separately. In diagnostic procedures, standard Sanger type sequencing (mostly performed as a dye-dideoxynucleotide terminator system) is still the most commonly used method. This allows using established techniques for interpreting those types of genetic information. Besides reviewing the foundation of drug resistance interpretation for HBV, different interpretation systems, either commercially available (TRUGENE, Abbott, ViroScore) or free to use (geno2pheno[HBV], HIV-GRADE HBV tool), are compared in this article.

Molecular epidemiology and genotyping of hepatitis B virus of HBsAg-positive patients in Oman

Background

Hepatitis B virus (HBV) infection is a major global health burden with distinct geographic public health significance. Oman is a country with intermediate HBV carrier prevalence; however, little is known about the incidence of HBV variants in circulation. We investigated the HBV genotype distribution, the occurrence of antiviral resistance, and HBV surface antigen (HBsAg) escape mutations in HBsAg-positive patients in Oman.

Methods

Serum samples were collected from 179 chronically HBV-infected patients enrolled in various gastroenterology clinics in Oman. HBV genotypes were determined by sequencing and phylogenetic analysis. Mutations in the HBV polymerase and the HBsAg gene were characterized by mutational analysis.

Results

HBV genotypes D (130/170; 76.47%) and A (32/170; 18.28%) are predominant in Oman. The HBV genotypes C and E were less frequent (each 1.18%), while the HBV genotypes B, G, F, and H were not detected. Four patients revealed HBV genotype mixtures (HBV-A/D and D/C). The analyses of vaccine escape mutations yield that 148/170 (87.06%) HBV sequences were wild type. 22/170 (12.94%) HBV sequences showed mutations in the “a” determinant of the HBsAg domain. Two patients showed the described HBV vaccine escape mutation sP120T. 8/146 (5.48%) HBV isolates harbored mutations in the HBV polymerase known to confer resistance against antiviral therapy. Especially the lamivudine resistance mutations rtL180M/rtM204V and rtM204I were detected.

Conclusion

This study shows the distribution of HBV genotypes, therapy resistance, and vaccine escape mutations in HBV-infected patients in Oman. Our findings will have a major impact on therapy management and diagnostics of chronic HBV infections in Oman to control HBV infection in this intermediate HBV-endemic country.

Hepatitis B virus genetic mutations and evolution in liver diseases

Hepatitis B virus (HBV) belongs to the genus Orthohepadnavirus of the Hepadnaviridae family and is approximately 3.2 kb in length. Owing to a lack of proofreading capacity during reverse transcription and a high replication rate, HBV exhibits as quasispecies. To detect the genetic mutations of HBV, many methods with different sensitivities and throughputs were developed. According to documentary records, HBV mutation and evolution were important vial parameters in predicting disease progression and therapeutic outcome. In this review, we separately discussed the correlation between HBV genomic mutations in four open reading frames and liver disease progression. Since some of the results were controversial from different laboratories, it remains to be seen whether functional analyses will confirm their role in modifying the course of infection.

Hepatitis B virus genotypes: Global distribution and clinical importance

At least 600000 individuals worldwide annually die of hepatitis B virus (HBV)-related diseases, such as chronic hepatitis B (CHB), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). Many viral factors, such as viral load, genotype, and specific viral mutations, are known to affect disease progression. HBV reverse transcriptase does not have a proofreading function, therefore, many HBV genotypes, sub-genotypes, mutants, and recombinants emerge. Differences between genotypes in response to antiviral treatment have been determined. To date, 10 HBV genotypes, scattered across different geographical regions, have been identified. For example, genotype A has a tendency for chronicity, whereas viral mutations are frequently encountered in genotype C. Both chronicity and mutation frequency are common in genotype D. LC and progression to HCC are more commonly encountered with genotypes C and D than the other genotypes. Pathogenic differences between HBV genotypes explain disease intensity, progression to LC, and HCC. In conclusion, genotype determination in CHB infection is important in estimating disease progression and planning optimal antiviral treatment.

Binding sensitivity of adefovir to the polymerase from different genotypes of HBV: molecular modeling, docking and dynamics simulation studies

AIM

To investigate the molecular mechanisms underlying the influence of DNA polymerase from different genotypes of hepatitis B virus (HBV) on the binding affinity of adefovir (ADV).

METHODS

Computational approaches, including homology modeling, docking, MD simulation and MM/PBSA free energy analyses were used.

RESULTS

Sequence analyses revealed that residue 238 near the binding pocket was not only a polymorphic site but also a genotype-specific site (His238 in genotype B; Asn238 in genotype C). The calculated binding free-energy supported the hypothesis that the polymerase from HBV genotype C was more sensitive to ADV than that from genotype B. By using MD simulation trajectory analysis, binding free energy decomposition and alanine scanning, some energy variation in the residues around the binding pocket was observed. Both the alanine mutations at residues 236 and 238 led to an increase of the energy difference between genotypes C and B (ΔΔG(C-B)), suggesting that these residues contributed to the genotype-associated antiviral variability with regard to the interaction with ADV.

CONCLUSION

The results support the hypothesis that the HBV genotype C polymerase is more sensitive to ADV than that from genotype B. Moreover, residue N236 and the polymorphic site 238 play important roles in contributing to the higher sensitivity of genotype C over B in the interaction with ADV.

Management of hepatitis B in developing countries

Hepatitis B is one of the leading causes of chronic hepatitis in developing countries, with 5% to 15% of the population carrying virus. The high prevalence is due to failure to adopt appropriate measure to confine the spread of infection. Most hepatitis B patients present with advanced diseases. Although perinatal transmission is believed to be an important mode, most infections in the developing world occur in childhood and early adulthood. Factors in developing countries associated with the progression of chronic hepatitis B (CHB) include co-infections with human immunodeficiency virus, delta hepatitis virus, hepatitis C virus, alcohol intake and aflatoxin. Treatment protocols extrapolated from developed countries may need modifications according to the resources available. There is some controversy as to when to start treatment, with what medication and for how long? There is now enough evidence to support that hepatitis B patients should be considered for treatment if they show persistently elevated abnormal aminotransferase levels in the last 6 mo, checked on at least three separate occasions, and a serum hepatitis B virus DNA level of > 2000 IU/mL. Therapeutic agents that were approved by Pure Food and Drug Administration are now available in many developing countries. These include standard interferon (INF)-α, pegylated INF-α, lamivudine, adefovir, entecavir and telbivudine. Drug resistance has emerged as a major challenge in the management of patients with CHB. The role of the universal vaccination program for effective control of hepatitis B cannot be emphasized enough.

Molecular epidemiology of hepatitis B virus

Although safe and effective vaccines for hepatitis B virus (HBV) have been available for nearly three decades, this virus kills at least 600,000 people annually worldwide and remains the leading global cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Because the HBV reverse transcriptase lacks a proofreading function, many HBV genotypes, subgenotypes, mutants, and recombinants exist. At least 10 HBV genotypes (HBV-A through J) with distinct geographic distributions have been identified; by definition, their complete genomic sequences diverge by more than 8%. HBV genotype is increasingly becoming recognized as an important factor in the progression and clinical outcome of HBV-induced disease. Infections by HBV-C or -D are significantly more likely to lead to cirrhosis and hepatocellular carcinoma than are infections by HBV-A or -B. Additionally, the hepatitis B e antigen seroconversion response to standard or pegylated interferon is more favorable in patients with HBV-A or -B than in those with HBV-C or -D. However, therapeutic responses to nucleos(t)ide analogues are generally comparable among HBV genotypes. In conclusion, genotyping of HBV is useful in identifying chronic hepatitis B patients who are at increased risk of disease progression, thereby enabling physicians to optimize antiviral therapy for these patients.