Clinical significance of hepatitis B virus genotypes, variants, and mutants

In Silico Prediction of Human Leukocytes Antigen (HLA) Class II Binding Hepatitis B Virus (HBV) Peptides in Botswana

Hepatitis B virus (HBV) is the primary cause of liver-related malignancies worldwide, and there is no effective cure for chronic HBV infection (CHB) currently. Strong immunological responses induced by T cells are associated with HBV clearance during acute infection; however, the repertoire of epitopes (epi) presented by major histocompatibility complexes (MHCs) to elicit these responses in various African populations is not well understood. In silico approaches were used to map and investigate 15-mers HBV peptides restricted to 9 HLA class II alleles with high population coverage in Botswana. Sequences from 44 HBV genotype A and 48 genotype D surface genes (PreS/S) from Botswana were used. Of the 1819 epi bindings predicted, 20.2% were strong binders (SB), and none of the putative epi bind to all the 9 alleles suggesting that multi-epitope, genotype-based, population-based vaccines will be more effective against HBV infections as opposed to previously proposed broad potency epitope-vaccines which were assumed to work for all alleles. In total, there were 297 unique epi predicted from the 3 proteins and amongst, S regions had the highest number of epi (n = 186). Epitope-densities (Depi) between genotypes A and D were similar. A number of mutations that hindered HLA-peptide binding were observed. We also identified antigenic and genotype-specific peptides with characteristics that are well suited for the development of sensitive diagnostic kits. This study identified candidate peptides that can be used for developing multi-epitope vaccines and highly sensitive diagnostic kits against HBV infection in an African population. Our results suggest that viral variability may hinder HBV peptide-MHC binding, required to initiate a cascade of immunological responses against infection.

Diagnostic accuracy of LAMP assay for HBV infection

Background

Detection of hepatitis B virus (HBV) is vital for the diagnosis of hepatitis B infection. A novel test loop‐mediated isothermal amplification (LAMP) has been successfully applied to detect various pathogens. However, the accuracy of LAMP in diagnosing HBV remains unclear. Therefore, in the present study, the accuracy of LAMP for HBV detection was evaluated systematically.

Methods

Embase, Cochrane Library, and PubMed databases were searched for studies using LAMP to detect HBV. Then, two researchers extracted data and assessed the quality of literature using the QUADAS‐2 tool independently. I² statistic and chi‐square test were analyzed to investigate the heterogeneity, and Deek's funnel plot assessed the publication bias. The pooled sensitivity (SEN), specificity (SPE), positive LR (PLR), negative LR (NLR), diagnostic odds ratio (DOR), and 95% confidence intervals were displayed in forest plots. We calculated the area under the curve (AUC) to assess the overall efficiency of LAMP for HBV detection.

Results

A total of nine studies with 1298 samples were finally included in this evaluation. The pooled sensitivity and specificity of HBV detection were 0.91 (95% CI: 0.89 ~ 0.92) and 0.97 (95% CI: 0.94 ~ 0.99), respectively. The PLR, NLR, and DOR were 16.93 (95% CI: 6.15 ~ 46.55), 0.08 (95% CI: 0.05 ~ 0.14), and 397.57 (95% CI: 145.41 ~ 1087.07). Besides, the AUC was 0.9872, and Deek's plot suggested that there existed publication bias in the studies.

Conclusion

Compared with PCR, LAMP is a simple, rapid, and effective assay to diagnose HBV. However, additional evidence is essential to confirm that LAMP can replace other methods in diagnosing HBV infection.

Genotype Matters in Patients with Acute-on-chronic Liver Failure Due to Reactivation of Chronic Hepatitis B

Background

Acute-on-chronic liver failure (ACLF) can be caused by reactivation of chronic hepatitis B virus (HBV) infection (HBV-ACLF). It’s unclear whether HBV genotypes affect the clinical and therapeutical outcomes of patients with HBV-ACLF. This study was to investigate the short-term antiviral response and overall survival in HBV-ACLF patients treated by tenofovir or entecavir.

Methods

Seventy-three consecutive patients with HBV-ACLF were stratified into genotype B group (n = 33) and C group (n = 40). They were prospectively followed-up.

Results

At 2 weeks, the genotype B group had significantly lower HBV-DNA load (P = 0.005), greater HBV-DNA decline (P = 0.026), higher proportion of patients with HBV-DNA < 500 IU/ml (P = 0.007), improved Child-Turcotte-Pugh (CTP; P = 0.032) and model for end-stage liver disease (MELD; P = 0.039) scores compared to the genotype C group. At three months, survivors in both groups had undetectable HBV-DNA loads, comparable CTP (P = 0.850) and MELD (P = 0.861) scores; the genotype C group had markedly lower overall survival rate than the B group (P = 0.013). The genotype (hazard ratio [HR]: 2.138; 95% confidence interval [CI]: 1.034–4.143; P = 0.041), MELD score (HR:1.664, 95%CI: 1.077–2.571; P = 0.022) and HBV-DNA decline (HR: 0.225, 95% CI: 0.067–0.758; P = 0.016) at 2 weeks were significantly associated with mortality at 3 months. No severe adverse event was noted.

Conclusions

Genotype B was associated with better short-term antiviral response and clinical outcome compared to genotype C in patients with HBV-ACLF.

A new hepatitis B virus e antigen-negative strain gene used as a reference sequence in an animal model

Infection with hepatitis B virus (HBV) e-antigen (HBeAg)-negative strains is increasingly prevalent. Currently, detailed information of the obtained natural HBV strain is not available except for the B genotype and HBeAg-negative. The aim of the present study was to characterize the natural genetic variation of the HBeAg-negative strain and investigate its function. The genic sequence was determined using Sanger sequencing, and compared to related sequences using alignment and phylogenetic analysis. In vivo, virus-specific serum markers were investigated in CBA/CaJ mice. The sequence had a full genome length of 3215 nucleotides. Sites 122, 125, 127, and 160 in S regions were identified as lysine, threonine, proline, and lysine respectively. The main four point variants including A1762T, G1764A, G1896A, and G1899A were detected in the full-length genome. The genotype of the sequence was B, with sub-genotype B2 and serological subtype adw2. The characterize of the natural genetic variation strain showed no reported drug-resistant variant in P region and no reported immune escape site in S region. The strain will increase viral replication and infection for mutations A1762T and G1764A in the basal core promoter region, and mutations G1896A and G1899A in the pre-core region. The G1896A variant resulted in a premature stop codon and abolished HBeAg expression. HBsAg persisted for 26 weeks and HBeAg was still negative in CBA/CaJ mice. The present sequence is representative of the HBeAg-negative genome and may serve as a valuable reference for studying HBeAg-negative strains. The present findings were successfully verified in CBA/CaJ mice, demonstrating good applicability of the sequence.

Tackling the Hepatitis B Disease Burden in India

Globally, approximately 240 people have been infected worldwide with hepatitis B Virus (HBV). India has approximately HBV carrier rate of 3.0% with a high prevalence rate in the tribal population. With a population of more than 1.25 billion, India has more than 37 million HBV carriers and contributes a large proportion of this HBV burden. While horizontal transmission in childhood appears to be a major route of transmission, the role of vertical transmission is probably underestimated. Blood transfusion and unsafe therapeutic injections continue to be important modes of transmission of HBV. There is a need for large field studies to better understand HBV epidemiology and identify high prevalence areas, and public health measures to prevent disease transmission and decrease the burden of the disease.

Rapid detection of hepatitis B virus in blood plasma by a specific and sensitive loop-mediated isothermal amplification assay

BACKGROUND

Hepatitis B virus (HBV) is an important blood-borne pathogen that causes hepatic inflammation and can lead to liver cirrhosis and hepatocellular carcinoma. Conventional methods of HBV detection are time consuming and require highly trained personnel and elaborate equipment. This report describes the development of a rapid, simple, specific, and sensitive loop-mediated isothermal amplification assay (LAMP) for detection of HBV genotypes A, B, C, D, E, and F in blood samples.

METHODS

HBV standard plasma panels and clinical donor plasma specimens were used for the development and validation of the LAMP assay. Amplification was performed at 60°C for 60 minutes using extracted DNA or heat-treated plasma specimens without DNA extraction. The assay was evaluated for its ability to detect various HBV genotypes and for its sensitivity, specificity, and time-point of detection.

RESULTS

The LAMP assay detected HBV genotypes A-F and demonstrated a sensitivity of 10-100 IU per reaction of HBV DNA. The assay also detected 69 of 75 (92%) HBV-positive donor plasma specimens tested and demonstrated a specificity of 100%.

CONCLUSIONS

These results demonstrate that our HBV-LAMP assay is rapid, sensitive and specific, and capable of detecting the major HBV genotypes. This assay could be used in clinical point-of-care settings, mainly in endemic and resource-limited environments for HBV diagnostics, donor screening, epidemiological studies, and therapeutic monitoring of patients undergoing antiviral treatment.

Hepatitis B virus genetic variation and TP53 R249S mutation in patients with hepatocellular carcinoma in Thailand

Chronic hepatitis B virus (HBV) infection and dietary exposure to aflatoxin B1 (AFB1) are major risk factors for hepatocellular carcinoma (HCC). The aim of this study was to evaluate the role of HBV genetic variation and the R249S mutation of the p53 gene, a marker of AFB1-induced HCC, in Thai patients chronically infected with HBV. Sixty-five patients with and 89 patients without HCC were included. Viral mutations and R249S mutation were characterized by direct sequencing and restriction fragment length polymorphism (RFLP) in serum samples, respectively. The prevalences of T1753C/A/G and A1762T/G1764A mutations in the basal core promotor (BCP) region were significantly higher in the HCC group compared to the non-HCC group. R249S mutation was detected in 6.2% and 3.4% of the HCC and non-HCC groups, respectively, which was not significantly different. By multiple logistic regression analysis, the presence of A1762T/G1764A mutations was independently associated with the risk of HCC in Thai patients.

Genome-wide microarray-based analysis of miRNAs expression in patients with acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a severe clinical syndrome that may cause a high mortality. However, the mechanism is still not clear. Characterization of the microRNA (miRNA) profiles in ACLF patients may provide new clues to the pathogenesis and management of this syndrome.

METHODS

Genome-wide microarray was performed to compare the different miRNA expression profiles in peripheral blood mononuclear cells of a pair of monozygotic twins, an ACLF patient and an HBV asymptomatic carrier (AsC). The case-control miRNA profiles were compared and confirmed by quantitative reverse transcription-polymerase chain reaction in 104 ACLF patients and 96 AsCs. A combined computational prediction algorithm was used to predict the potential target genes.

RESULTS

Forty-five miRNAs were increased and eight miRNAs were decreased in the ACLF group. The expressions of hsa-let-7a and hsa-miR-16 were increased by 8.58- and 8.63-fold in ACLF patients compared with that in AsCs, respectively (P<0.001). CARD8, BCL2, IL1RAPL1, LTB, FZD10 and EDA were identified as the target genes of hsa-miR-16; MAP4K3, OPRM1, IGF2BP1 and CERCAM were verified as the target genes of hsa-let-7a.

CONCLUSIONS

Our results showed that there is a close relationship between specific miRNAs of peripheral blood mononuclear cells and ACLF. hsa-miR-16 and hsa-let-7a may contribute to the development of ACLF.

Molecular analysis of hepatitis B virus associated with vaccine failure in infants and mothers: a case-control study in Thailand

Perinatal transmission of hepatitis B virus (HBV) has been controlled incompletely despite adequate immunoprophylaxis in infants. The aim of this study was to characterize virological factors of HBV associated with vaccine failure in Thailand. Sera of 14 infected infants (13 HBeAg-positive and one HBeAg-negative) with vaccine failure and their respective mothers (group M1) were tested quantitatively for HBV DNA by real-time PCR, HBV genotypes and mutations were characterized by direct sequencing. Sera collected from 15 HBeAg-positive (group M2) and 15 HBeAg-negative (group M3) mothers whose infants had been vaccinated successfully served as controls. The results showed that group M1 and group M2 mothers had equal titers of HBV DNA but higher titers than group M3. All infected infants and their respective mothers had the same HBeAg status and HBV genotypes. DNA analysis in a pair of HBeAg-negative infant and mother revealed that both were infected with an HBV precore mutant (G1896A). Escape mutants in the "a" determinant region (residues 144 and 145) were detected in two (14%) infected infants. The prevalence of BCP mutations/deletions in groups M2 and M3 was higher significantly than in group M1 (P = 0.022 and P < 0.001, respectively). In conclusion, instead of the HBeAg status, a high titer of HBV DNA in mothers was the major contributor to perinatal transmission of HBV. Escape mutants might be associated with vaccine failure in some infants. BCP mutations/deletions in mothers might contribute to the prevention of mother-to-infant transmission of HBV.

Prevalence of Genotype D and Precore/Core Promoter Mutations in Hepatitis B Virus-infected Population of North India

Hepatitis B virus (HBV) isolates (21) from Punjab (North India) were studied for genotype distribution and precore/core promoter mutations. Assays of alanine aminotransaminase (ALT) and HBeAg were performed in all isolates. Genotypes were determined in all the samples by restriction fragment length polymorphism and the precore/core promoter mutations were studied by amplification and by direct sequencing of precore/core promoter region. Sixty-two percent of the isolates had higher ALT levels and 57% of the isolates were HBeAg negative. It was observed that 90% of the isolates were HBV D genotype (subgenotype D1 and D2) and 10% of the isolates were HBV A genotype (subgenotype A1). Amplification and sequencing of the precore/core promoter region showed 1762(A-T) and 1764(G-A) mutations in 29% and 19% of the isolates, respectively. 1809(C/T) mutation was observed in 71% of the isolates under study. Novel precore and core promoter mutations like 1690(A), 1695(A/T/G), 1700(A/C), 1703(c), 1850(A) and 1915(A/G) were observed in HBV-infected population of the state of Punjab (North India). Deletion and insertional mutations were also observed in some patients. (J CLIN EXP HEPATOL 2011;1:73-76).

A336C/A336T/T337C variations in HBV core gene and spontaneous hepatitis B e antigen loss in chronic hepatitis B patients

BACKGROUND

A336C/A336T/T337C variations in HBV core gene were demonstrated to relate to the decreases in serum HBV DNA levels and HBV replication in chronic hepatitis B patients. Usually the drastic decrease in serum HBV DNA levels correlates with spontaneous HBeAg loss during the course of chronic HBV infection. The aim of the present study was to investigate whether there was correlation between A336C/A336T/T337C variations and spontaneous HBeAg loss

METHODOLOGY/PRINCIPAL FINDINGS

A modified PCR-RFLP assay and ELISA were adopted to determine A336C/A336T/T337C variations and serum HBeAg levels in chronic hepatitis B patients without any antiviral therapy, respectively, whereas G1896A variation and HBV genotype were detected using Taqman-PCR assay. RFLP pattern C, E, G, C/G mixture and a new pattern C' were found in this study. A336C/A336T/T337C variations occurred in 40/166(24.1%) chronic hepatitis B patients. Chi-square test showed that C336/T336/C337 variants was more frequent in chronic hepatitis B patients with A1896 variants than those with the wild type G1896 (χ2 = 4.7, P = 0.03), and moreover, patients with C336/T336/C337 variants had a significantly lower HBeAg-positive percentage than those with the wild type A336/T337. Binary logistic regression identified genotype B (OR = 4.1, 95%CI = 1.8-9.2, P = 0.001), the presence of C336/T336/C337 variants (OR = 3.2, 95%CI = 1.2-8.5, P = 0.02) and A1896 variants (OR = 7.8, 95%CI = 3.3-18.5, P < 0.001) as independent factors associated with spontaneous HBeAg loss.

CONCLUSION/SIGNIFICANCE

A336C/A336T/T337C were naturally occurring polymorphisms in HBV core gene, and moreover, the presence of C336/T336/C337 variants was first demonstrated to be an independent factor associating with spontaneous HBeAg loss in chronic hepatitis B patients.

Clinical, epidemiological characteristics and indications for liver biopsy and treatment in immigrants with chronic hepatitis B at a referral hospital in Madrid

The increase in immigration from less developed countries to Europe has led to an increase in the incidence of hepatitis B infection. The objective of this study was to describe the clinical, epidemiological characteristics and indications for treatment of chronic hepatitis B in a cohort of immigrants, given the relative lack of current evidence. We performed a noninterventional retrospective chart review; different characteristics depending on geographical origin were compared. A case-control study was also performed to describe factors potentially associated with chronic or past hepatitis B virus (HBV) infection. We selected a random sample of 436 patients out of the 2989 immigrants attending during the study period (1989-2008). Hepatitis B serology was performed in 74% (322/436): 10.6% had chronic HBV infection (95% CI: 7.4-13.7%), and 46.9% had evidence of past infection (95% CI: 41.7-52.0%). The average age was 31 years, 60% were men, and 70% were sub-Saharan Africans. Chronic infection was related to being men (OR 2.03; 95%CI: 1.29-3.18), younger (OR 0.98; 0.96-0.99) and sub-Saharan African (OR 5.41; 2.71-10.83). Past or current infection was related to male sex (OR 2.80; 1.81-4.30), longer time elapsed until first seen at the unit (OR 0.998; 0.997-1.000), HIV infection (OR 4.99; 1.15-21.60) and being sub-Saharan African (OR 15.46; 8.97-27.18). These associations were not confirmed after adjustment for geographical origin. In 27% and 29.5% of patients, liver biopsy and treatment, respectively, would have been indicated. Prevalence of chronic HBV infection amongst immigrants is high, especially in sub-Saharan Africans. Almost a third could be considered for liver biopsy or antiviral therapy.

A case-control study on sequence variations in the enhancer II/core promoter/precore and X genes of hepatitis B virus in patients with hepatocellular carcinoma

PURPOSE

To evaluate the sequence variations in the enhancer II (EnhII)/basal core promotor (BCP)/precore (PC) and X genes of hepatitis B virus (HBV) in Thai patients with hepatocellular carcinoma (HCC) by conducting a cross-sectional case-control study.

METHODS

As much as 60 patients with HCC and 60 patients without HCC, who were matched for sex, age, hepatitis B e antigen (HBeAg) status, and HBV genotype, were included. Viral mutations in the EnhII/BCP/PC and X regions were characterized by direct sequencing in serum samples.

RESULTS

The prevalence of T1753C/A, A1762T/G1764A and G1899A mutations were significantly higher in the HCC group compared to the non-HCC group (43.3 vs. 23.3%, P = 0.02; 88.3 vs. 53.0%, P < 0.001; and 35.0 vs. 8.3%, P = 0.001, respectively). No significant difference between groups was found with respect to G1613A, C1653T, C1766T/T1768A, A1846T/C, T1858C, and G1896A mutations. By multiple logistic regression analysis, the presence of cirrhosis, A1762T/G1764A and G1899A mutations were independently associated with the risk of HCC.

CONCLUSION

These data suggested that A1762T/G1764A and G1899A mutations were associated with the development of HCC in Thai patients.

Drug delivery systems and liver targeting for the improved pharmacotherapy of the hepatitis B virus (HBV) infection

In spite of the progress made in vaccine and antiviral therapy development, hepatitis B virus (HBV) infection is still the most common cause of liver cirrhosis and hepatocellular carcinoma, with more than 400 million people chronically infected worldwide. Antiviral therapy with nucleos(t)ide analogues and/or immunomodulating peptides is the only option to control and prevent the progression of the disease in chronic hepatitis B (CHB)-infected patients. So far, the current antiviral monotherapy remains unsatisfactory because of the low efficacy and the development of drug resistance mutants. Moreover, viral rebound is frequently observed following therapy cessation, since covalent closed circular DNA (cccDNA) is not removed from hepatocytes by antiviral therapy. First, this review describes the current pharmacotherapy for the management of CHB and the new drug candidates being investigated. Then, the challenges in the development of drug delivery systems for the targeting of antiviral drugs to the liver parenchyma are discussed. Finally, perspectives in the design of a more efficient pharmacotherapy to eradicate the virus from the host are addressed.

Epidemiology of hepatitis B and C viruses: a global overview

This article reviews the prevalence, disease burden, genotype distribution, and transmission patterns of hepatitis B virus (HBV) and hepatitis C virus in the 6 World Health Organization regions. The global epidemiology of hepatitis B and C demonstrates a predominantly declining prevalence of the diseases. Improvement in the control of hepatitis B has been largely achieved with implementation of a more universal HBV vaccine program, although a large gap still remains in the effort toward global prevention of hepatitis B. The transmission of hepatitis C has been greatly impacted by mandatory screening of blood donors in most countries in the world, although intravenous drug use continues to be a major source of infection. Public education regarding the risks of exposure to infected paraphernalia as well as household items such as razors is necessary in the continuing effort to curb this disease.

High prevalence of HBV genotype D in Syria and the clinical characteristics of hepatitis B e antigen-negative chronic hepatitis B

Hepatitis B virus (HBV) genotype D and hepatitis B e antigen (HBeAg) negative chronic hepatitis are the most prevalent in Mediterranean countries. No data have ever been published on their prevalence in Syria, a country of intermediate endemicity for HBV. The aims of the current study were to determine the HBV genotype distribution in Syria, the prevalence of HBeAg-positive and HBeAg-negative chronic hepatitis and to analyse the clinical characteristics of each group. A total of 220 patients were included. Ninety-seven percent of the patients were of genotype D, and 72% were HBeAg negative. The HBeAg-negative patients were older, had a lower viral load, had more cirrhosis and the mode of contamination was known less than for HBeAg-positive patients. These findings have major implications in understanding the natural history of the infection and are of great relevance in the choice of therapy.

Low pretreatment serum HBsAg level and viral mutations as predictors of response to PEG-interferon alpha-2b therapy in chronic hepatitis B

BACKGROUND

Viral genomic mutations have become increasingly recognized as being associated with the outcome of chronic HBV infection. However, the role of viral mutations as a predictor of response to pegylated-interferon (PEG-IFN) therapy has so far remained unclear.

STUDY DESIGN

Viral mutations in the enhancer II/basal core promoter (BCP)/precore and the pre-S regions were characterized by direct sequencing in pretreatment serum samples of 50 patients with chronic hepatitis B (33 HBeAg-positive and 17 HBeAg-negative), who were treated for 48 weeks with PEG-IFN alpha-2b.

RESULTS

Sustained virological response at 48 weeks post treatment, defined as HBeAg seroconversion and HBV DNA<2000IU/mL for HBeAg-positive patients, and HBV DNA<200IU/mL for HBeAg-negative patients, was achieved in 12 (36.4%) and 6 (35.3%) of HBeAg-positive and HBeAg-negative patients, respectively. Response to PEG-IFN therapy correlated to low pretreatment HBsAg level but did not correlate with HBV genotype, pretreatment alanine transaminase and HBV DNA levels. In HBeAg-positive hepatitis, PEG-IFN response correlated with the appearance of double BCP mutations (A1762T/G1764A) at baseline (P=0.041). In the HBeAg-negative group, response to PEG-IFN therapy was associated with the presence of pre-S mutation/deletions (P=0.028). Multivariate analysis identified low pretreatment HBsAg level as an independent factor associated with SVR in both groups.

CONCLUSIONS

Pretreatment quantitative HBsAg determination is useful for predicting response to PEG-IFN therapy. The presence of double BCP and pre-S mutation/deletions at entry may be associated with a high rate of antiviral response in HBeAg-positive and HBeAg-negative hepatitis, respectively.

Hepatitis B virus mutations potentially conferring adefovir/tenofovir resistance in treatment-naive patients

Anti-hepatitis B virus (HBV) therapy leads to the emergence of mutant viral strains during the treatment of chronic hepatitis B with nucleos(t)ides analogues. The existence of HBV variants with primary antiviral resistance may be important for treatment choice. We studied two patients with chronic HBV infection by sequencing the HBV polymerase gene. They had adefovir- and tenofovir-related mutations in the viral polymerase, although they had never been treated. These mutations were rtV214A/rtN238T in one patient and rtA194T in the other. Thus, mutations in untreated patients deserve cautious surveillance. These data indicate that mutations that can theoretically confer adefovir or tenofovir resistance may emerge in treatment-naive patients.

Role of genotype and precore/basal core promoter mutations of hepatitis B virus in patients with chronic hepatitis B with acute exacerbation

OBJECTIVE

The results of long-term, follow-up studies show that the severity and frequency of acute exacerbation of chronic hepatitis B virus (HBV) are associated with the development of liver cirrhosis in chronic HBV infection. The aim of this study was to investigate the relationship between virological factors of HBV and the severity of acute exacerbation.

MATERIAL AND METHODS

Fifty-one chronic hepatitis B patients with symptomatic acute exacerbation without antiviral therapy were enrolled in the study. Genotype of HBV was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Precore (A1896) and basal core promoter (BCP) mutations (T1762 & A1764) were determined by PCR and direct sequencing.

RESULTS

Thirty-nine patients had genotype B, 11 patients had genotype C, and 1 patient had an unclassified genotype. Thirty-two patients had precore mutation and 24 patients had BCP mutation. After adjusting for age, gender, aspartate aminotransferase (ASAT) level, albumin level, and platelet count by multiple logistic regression test, precore mutation had a protective effect on the occurrence of hepatic decompensation (p=0.046), and genotype and BCP mutations were not associated with the occurrence of hepatic decompensation.

CONCLUSIONS

HBV precore mutation may confer less severe liver disease during acute exacerbation of chronic HBV. Genotype and BCP mutations did not have a significant association with the occurrence of hepatic decompensation.

[Molecular virology of the hepatitis B virus]

The hepatitis B virus (HBV) belongs to the hepadnavirus family. The genome of the virus, formed by a small DNA molecule with 3,200 base pairs, has 4 strongly overlapping protein coding regions: ORF preS/S, corresponding to the envelope proteins that constitute the HBV surface antigen (HBsAg); ORF preC/C, which encodes the viral capsid component (core antigen or HBcAg) and a non-structural protein that, after postranslation modification, is secreted and constitutes the "e" antigen (HBeAg); ORF P, which encodes the viral polymerase (polyprotein with DNA polymerase activity, reverse transcriptase and RNAase), and ORF X, which encodes a protein that acts as a multifunctional regulator for both the viral and cell cycles. HBV has a mutation rate of 1.4-3.2 x 105 substitutions/nucleotide/year. As a result of this variability, the virus circulates as a complex mixture of genetic variants, constituting a semi-species, that evolves throughout the infection depending on the evolutionary pressure of factors such as the immune response and antiviral treatments. Based on this variability, HBV has been classified into 8 genotypes (A-H) defined by a difference of more than 8% in the sequences of the complete viral genome. This variability is also responsible for HBV resistance to antiviral treatments with nucleotide and nucleoside analogs. Diagnosis of HBV infection includes determination of virological markers: viral antigens (HBsAg, HBeAg), specific antibodies (anti-HBc, anti-HBe, anti-HBs) and study of HBV-DNA for its detection and quantification and determination of genotypes and viral variants.

HBVRegDB: annotation, comparison, detection and visualization of regulatory elements in hepatitis B virus sequences

BACKGROUND

The many Hepadnaviridae sequences available have widely varied functional annotation. The genomes are very compact (approximately 3.2 kb) but contain multiple layers of functional regulatory elements in addition to coding regions. Key regions are subject to purifying selection, as mutations in these regions will produce non-functional viruses.

RESULTS

These genomic sequences have been organized into a structured database to facilitate research at the molecular level. HBVRegDB is a comparative genomic analysis tool with an integrated underlying sequence database. The database contains genomic sequence data from representative viruses. In addition to INSDC and RefSeq annotation, HBVRegDB also contains expert and systematically calculated annotations (e.g. promoters) and comparative genome analysis results (e.g. blastn, tblastx). It also contains analyses based on curated HBV alignments. Information about conserved regions - including primary conservation (e.g. CDS-Plotcon) and RNA secondary structure predictions (e.g. Alidot) - is integrated into the database. A large amount of data is graphically presented using the GBrowse (Generic Genome Browser) adapted for analysis of viral genomes. Flexible query access is provided based on any annotated genomic feature. Novel regulatory motifs can be found by analysing the annotated sequences.

CONCLUSION

HBVRegDB serves as a knowledge database and as a comparative genomic analysis tool for molecular biologists investigating HBV. It is publicly available and complementary to other viral and HBV focused datasets and tools http://hbvregdb.otago.ac.nz. The availability of multiple and highly annotated sequences of viral genomes in one database combined with comparative analysis tools facilitates detection of novel genomic elements.

A pilot study of extended duration peginterferon alfa-2a for patients with hepatitis B e antigen-negative chronic hepatitis B

OBJECTIVES

Forty-eight weeks of peginterferon alfa-2a is the approved regimen for chronic hepatitis B (CHB). Standard interferon is more effective for hepatitis B e antigen (HBeAg)-negative CHB when given for longer than 1 yr. This study evaluated peginterferon alfa-2a for 60 wk, alone or in combination with lamivudine.

METHODS

Thirteen patients with HBeAg-negative CHB received peginterferon alfa-2a (180 microg/week) for 60 wk or peginterferon alfa-2a (180 microg/week) for 12 wk followed by 48 wk of peginterferon alfa-2a plus lamivudine. The primary end point, sustained virologic response (SVR), was defined as a reduction in hepatitis B virus deoxyribonucleic acid (HBV DNA) of >or=2 log10 copies/mL and HBV DNA<20,000 copies/mL at 24 wk of follow-up (week 84). Hepatitis B surface antigen (HBsAg) concentrations were analyzed and compared to changes in HBV DNA.

RESULTS

SVR was achieved by 9/13 patients (69%). At week 84, HBV DNA was undetectable by polymerase chain reaction in 5/13 (38%) patients, and 3 additional patients had a sustained 2-3 log reduction in HBV DNA. Five patients demonstrated a >90% decrease in HBsAg concentration at week 60, including 3 with undetectable HBV DNA at week 84 and a fourth who met criteria for SVR.

CONCLUSIONS

Sixty weeks of peginterferon alfa-2a with or without lamivudine resulted in a higher rate of SVR compared to historical controls with HBeAg-negative CHB treated with 48 wk of pegylated interferon. Larger studies are necessary to assess if longer duration therapy is more effective than the standard regimen and results in a greater decline in HBsAg concentration.

Clinical implications of HIV and hepatitis B co-infection in Asia and Africa

Hepatitis B virus (HBV) is the leading cause of chronic liver disease and liver-related death worldwide, with the majority of these cases occurring in areas of Africa and Asia where HBV prevalence is high. Many of the countries that are affected by hepatitis B are also affected by a high HIV burden, leading to frequent HIV/HBV co-infection. The consequences of co-infection, including increased liver-related morbidity and mortality, increased hepatitis B viral replication, immune reconstitution to HBV in the setting of antiretroviral therapy, and hepatotoxicity from antiretroviral drugs, are especially important in regions with expanding antiretroviral programmes. Little data, however, are available on HIV/HBV co-infection from regions with high chronic hepatitis B prevalence. This Review discusses the epidemiology, natural history, pathogenesis, and management of HIV/HBV co-infection from these areas. Topics for future research relevant to HIV/HBV co-infection in Africa and Asia are also highlighted.

Hepatitis B virus DNA in unusual serological profiles of hepatitis B surface antigen-positive sera

On the basis of a seroepidemiological survey of hepatitis B virus (HBV) infection conducted on 6208 random serum samples from four provinces of Thailand, we found 19 of 246 (7.7%) hepatitis B surface antigen (HBsAg)-positive samples with unusual serological constellations of HBV infection. Ten samples tested positive for HBsAg, anti-HBc (anti-hepatitis B core antibody), and anti-HBs (anti-hepatitis B surface antibody) markers (group I), 3 specimens were HBsAg and anti-HBs positive without detectable anti-HBc (group II), and the remaining 6 specimens showed only HBsAg (group III). In group I, 7 of 10 HBsAg-positive sera could be confirmed by HBsAg neutralization, yielding positive results for all samples. None of the group II sera were available in sufficient amounts for confirmation. In group III, five of six sera were confirmed by HBsAg neutralization, with four showing a positive reaction. HBV DNA was detected in 7 of 10 (70%) specimens in group I, in 1 of 3 (33.3%) specimens in group II, and in 3 of 6 (50%) specimens in group III. On the basis of HBsAg neutralization, HBV DNA was found in five of seven (71.4%) HBsAg-positive samples in group I and in three of four (75%) HBsAg-positive samples in group III, whereas the one confirmed HBsAg-negative sample in group III also remained negative for HBV DNA. Amino acid sequences were compared with those specifying the "a" determinant of the wild-type virus, particularly focusing on HBV-S protein variations between positions 110 and 160. Among 11 HBV DNA-positive sera, G145A was detected in 2 samples in group I, with the remaining samples identical to the wild-type virus. These unusual serological profiles may be due to the altered immune response of the host or to HBV variants.

Novel anti-hepatitis B agents: A focus on telbivudine

Although preventable by vaccination, hepatitis B infection is common, affecting more than 350 million individuals worldwide. Chronic hepatitis B infection is associated with the complications of chronic liver disease including cirrhosis and hepatocellular carcinoma. Current agents designed to target hepatitis B are hindered by the development of resistance, poor tolerability or limited efficacy and a demand for new agents and strategies continues. This review focuses on telbivudine, a novel agent in the fight against hepatitis B.

Natural history of chronic hepatitis B in co-infected patients

HIV co-infection influences the course and natural history of hepatitis B virus (HBV) infection by impairing the quantity and quality of the innate and adaptive immune response. The rates of spontaneous resolution after acute infection and spontaneous anti-HBe and anti-HBs seroconversions are decreased, and levels of HBV replication are increased in HIV-infected patients. A more rapid progression of liver fibrosis and a higher rate of cirrhosis decompensation (but not hepatocellular carcinoma) have been demonstrated in co-infected patients. The risk of HBV-associated end-stage liver disease and liver-related mortality may be increased by HIV co-infection. Antiretroviral therapy may trigger spontaneous anti-HBe and anti-HBs seroconversion and/or a better immune control of HBV replication by restoring adaptive immunity, but can also increase hepatitis flares. Reactivation of chronic hepatitis B has been observed after suspension of anti-retrovirals with anti-HBV activity or after occurrence of HBV resistance to lamivudine. Future research should focus on: the impact of HIV-induced changes in innate and adaptive immune response and modifications induced by anti-retroviral therapy that may impact on progression of advanced chronic hepatitis B; the association between HBV genotype and clinical course of disease; and the role of occult HBV infection as a co-factor with other causes of liver injury.

Emerging therapeutics for chronic hepatitis B

Hepatitis B is a global health problem. Patients with chronic hepatitis B (CHB) carry a significant risk to eventually develop cirrhotic liver disease. Recent therapeutic advances against CHB offer excellent potential for long-term suppression of hepatitis B virus (HBV) replication during antiviral therapy, and occasionally a durable remission off medication. Selection of appropriate patients for antiviral therapy depends on identification of HBV replication and an elevated alanine aminotransferase level or histologic liver injury. Pegylated interferon alpha offers potent immunomodulatory and antiviral activity with the potential for durability, but also with adverse effects and significant cost. The nucleoside or nucleotide analogs, lamivudine, adefovir, and entecavir, suppress HBV replication and are extremely well-tolerated, but long-term or even lifelong therapy is required. Most experience has been gained with lamivudine, but viral resistance occurs frequently. Newer analogs appear to be relatively free of this problem. Approaches using a combination of agents have promise, but have yet to be proven superior to individual drugs alone.

Management of drug-resistant chronic hepatitis B

Lamivudine, adefovir, and entecavir are safe and effective orally administered inhibitors of hepatitis B virus (HBV) replication, but drug-resistant strains of HBV with point mutations in the HBV polymerase gene are being reported with prolonged treatment that can lead to viral rebound and serum alanine aminotransferase flares. Salvage treatment with antiviral agents including investigational nucleoside/nucleotide analogues is available but highlights the limitations and hazards of sequential antiviral monotherapy for chronic HBV. Studies of pegylated interferon combined with an antiviral agent or dual nucleoside/nucleotide combination therapy are awaited to minimize the incidence of drug-resistant HBV and improve long-term outcomes.

Prognostic analysis in chronic hepatitis B patients: a retrospective study of 216 cases about Scheuer scores, in situ expression of viral antigens and tissue hepatitis B virus DNA levels

BACKGROUND

Most of the previous studies of patients with chronic hepatitis B virus (HBV) infection concentrated on serum samples. Liver biopsy specimens for HBV have not been systematically analyzed. This study was performed to analyze some histopathological indicators (Scheuer scores, the expression of HBV antigens in situ, HBV DNA quantification) in the biopsy samples and showed the relationship among them and the prognosis of chronic hepatitis.

METHODS

A total of 216 consecutive chronic HBV-infected patients were followed up by clinical and laboratory data and classified into two groups at first: carcinogenesis and non-carcinogenesis. The non-carcinogenesis also included two groups: cirrhosis and non-cirrhosis. The non-cirrhosis was still divided into fluctuation and normalization at last. Histological activity index was described by Scheuer scores. Two-step immunohistochemical staining showed the expression of viral antigens in situ. Tissue HBV DNA levels were determined by fluorescence quantitative real-time PCR.

RESULTS

Regression analysis revealed significant positive correlations between the expression of hepatitis B e antigen (HBeAg) and grading, as well as between hepatitis Bx (HBx) protein and grading or staging of Scheuer scores. Positive correlations between grading or staging and prognosis were statistically significant. The expressions of HBeAg and HBx protein were higher in patients with cirrhosis than those without cirrhosis. Scheuer score was the most important indicator of prognosis.

CONCLUSIONS

HBeAg and HBx protein can be used as indicators of hepatitis activity and their positive expressions increase the risk for cirrhosis remarkably. In addition to be a marker of liver damage, Scheuer score is the most reliable indicator of the prognosis.

Genotyping of hepatitis B virus (HBV) by oligonucleotides microarray

Oligonuleotides (oligo) microarray is a promising method for virus genotyping. In this study, we developed an oligo microarray used for genotyping hepatitis B virus (HBV). It consists of 15 probes targeting HBV genotypes A-G and two genotypes of apes, and one conserved probe selected from the HBV pre-S region. To test a clinical sample, the gene targets of clinical samples were amplified and labelled with Cy5-dCTP in a PCR reaction using primers covering the flanking region of the HBV pre-S gene. Following purification, the labelled PCR products were hybridized to the microarray. In an analysis of 96 HBV patients' serum samples using our developed microarray, we identified 34 genotype B, 60 genotype C and 2 genotypes B/C coinfection samples. Sequencing results of 24 randomly selected samples agreed 100% with microarray data. Geographic distribution of genotypes C and B was also divergent, 95.7% (44/46) of genotype C and 64.0% (32/50) of genotype B samples were collected from Northern and Southern China, respectively. The accuracy of genotyping was confirmed by analyzing DNA sequences of 24 samples. It is demonstrated that low-density oligo microarray can serve as a reliable and time-saving method to HBV genotyping from patient's sera.

Hepatitis B virus genotypes, core promoter variants, and precore stop codon variants in patients infected chronically in North-Eastern Italy

The hepatitis B virus (HBV) genotypes distribution and the core promoter (CP)/precore (PC) variability were evaluated by a line probe assay in 272 patients infected chronically enrolled consecutively in an area of the North-Eastern Italy. Seven out of the eight genotypes were detected. Italian subjects (83% of the sample) were infected mainly by genotype D (73%) and A (26%); genotype F, and genotype H, were detected only in one subject. In foreigners, the genotype distribution reflected the distribution described for the areas of origin, that is, in Asia genotypes B, C, and D; in Africa genotypes A and E. CP and PC variants prevalence rates were 51% and 60%, respectively, and were significantly higher in Italian patients, probably in relation to their older age. In the analysis restricted to genotypes A and D, PC wild type was linked strongly to genotype A (OR = 4.08, 95% CI = 3.07-5.43, P < 0.0001). In genotype A-infected patients, only e seroconversion was associated significantly with CP variants. In genotype D-infected subjects, CP variants were linked significantly to older age and to a higher e seroconversion rate, while PC variants also showed a strong relationship with an ALT lower activity and a lower viral load. In multivariate analysis, HBeAg positivity was associated strongly and independently with younger age, genotype A and CP wild type. Independent determinants of higher viral loads were recognized by increasing age, in male gender and concomitant presence of HBeAg and the CP wild type virus.

Evaluation of fluorescent hybridization biprobe PCR and melting curve assay

AIM: To evaluate a fluorescent hybridization biprobe PCR and melting curve assay for detection of (hepatitis B virus) YMDD mutation associated with lamivudine therapy.

METHODS: HBV DNA and YMDD mutations in the 217 clinical serum specimens from patients with chronic HBV infection who were treated with lamivudine (100 mg/d) were detected by the fluorescence quantitative polymerase chain reaction (PCR) using TaqMan probe (FT-PCR) and the fluorescent hybridization biprobe PCR and melting curve assay (FH-PCR-MC), respectively. Seventy-eight positive sera were then genotyped by nested PCR with six pairs of HBV genotype-specific primes (A to F), and the cloned DNA fragments derived from conventional PCR of HBV YMDD of 30 positive sera were sequenced.

RESULTS: Among 217 samples, 75.6%(164/217) were HBV DNA positive, and 67.7% (147/217) were HBV YMDD positive, including YMDD 44.9%(66/147), YIDD 22.5%(33/147),YVDD 17.7%(26/147),YI/VDD 10.9%(16/147), and others 4.0%(6/147). In HBV DNA≥10⁷copies/L, all the positive and mutant rates of YMDD have no significant difference in different HBV DNA levels. Among 78 genotype samples (genotype C 89.8%, B 8.9% and D 1.3%), the positive and mutant rates of YMDD were 100%(78/78) and 58.97%(46/78) respectively. One genotype D was YIDD/YVDD. The mutant rates of YMDD in genotype B and C were 71.4% and 55.7% respectively, but have no marked difference (P >0.5). Using the results by DNA sequencing as reference standard, the relative specificity, sensitivity and over-all accordance of FH-PCR-MC were 96.3% (26/27), 100% (3/3) and 96.7% (29/30) respectively. The results of YMDD typing by FH-PCR-MC were confirmed by the sequencing of clones.

CONCLUSION: The fluorescent hybridization biprobe PCR and melting curve assay kit in detection of HBV YMDD mutation has high sensitivity and specificity. It is a convenient and rapid test kit, and may be used in YMDD genotyping.