A case-control study for differences among hepatitis B virus infections of genotypes A (subtypes Aa and Ae) and D

HBV genotypes: relevance to natural history, pathogenesis and treatment of chronic hepatitis B

Although chronic HBV infection is the leading cause of chronic liver disease and death worldwide, there are substantial differences in its clinical courses regarding prevalence, mode of transmission, characteristics of each phase, responses to antiviral therapy, and development of cirrhosis and hepatocellular carcinoma, according to geographical areas (Asia versus Western Europe and North America versus Africa). Furthermore, the clinical course in infected individuals depends on a complex interplay among various factors including viral, host, environmental and other factors. Recently, understanding of molecular characteristics of the prevailing HBV genotypes, frequently accompanied mutations and their clinical implications might explain these geographical differences more pertinently. Hence, in this article, we review the global epidemiology and the natural history of HBV infection, with emphasis on summarizing the different HBV genotypes according to regions.

Treatment of chronic hepatitis B with nucleos(t)ide analogues

Recently antiviral therapies for chronic hepatitis B using nucleos(t)ide analogues have become standard treatment modalities on the basis of several independent guidelines, starting with those of the American Association for the Study of Liver Diseases (AASLD) and other such organizations and bodies, including the European Association for the Study of the Liver (EASL), the Asian Pacific Association for the Study of the Liver (APASL), and the Japanese Ministry of Health, Labour and Welfare (MHLW)'s research team. The philosophies underlying such treatment strategies are considered basically equivalent. MHLW's guidelines define subjects for medical intervention to be cases measuring alanine aminotransferase (ALT) ≥31 IU/L, with serological hepatitis B virus (HBV) DNA level ≥5 log copies/mL for hepatitis B e antigen (HBeAg)-positive cases, and serological HBV DNA level ≥4 log copies/mL for HBeAg-negative cases. These Japanese guidelines advocate entecavir as the first-line treatment option for nucleos(t)ide-naïve patients, and combination treatment of lamivudine and adefovir as the basis of treatment for patients with lamivudine- and/or entecavir-resistant viruses. Of particular note for patients undergoing lamivudine treatment with persistent HBV DNA level < 2.1 log copies/mL is the recommendation of a switch to entecavir. Early detection of drug-resistant virus is desirable after initiation of nucleos(t)ide analogue treatment, but such a procedure is not uniformly available at all medical institutions. Nevertheless, timely estimation of potential early-stage drug-resistant virus development is crucial for getting a head start on treatment. HBV core-related antigen (HBcrAg) level or HBV DNA level are considered useful markers for the appearance of such drug-resistant viruses.

The effect of the G1888A mutation of subgenotype A1 of hepatitis B virus on the translation of the core protein

A distinctive characteristic of subgenotype A1 of hepatitis B virus is G1888A in the precore region. This transition introduces an out-of-frame AUG, creating an overlapping upstream open reading frame (uORF), terminating five nucleotides downstream from the core AUG. This uORF can potentially be translated into a seven amino acid peptide. In addition to stabilizing the encapsidation signal by forming a base pair with T1871, this mutation may affect translation of the core protein. The aim of this study was to use reporter constructs to determine whether G1888A had any modulating effect on core protein translation. The complete core gene with part of the precore of subgenotype A1 was cloned into the amino terminal of a green fluorescent protein (GFP) plasmid. Core/GFP fusion protein expression was measured using flow cytometry following transfection of Huh 7 cells. The introduction of uORF resulted in an 18.75% reduction of core gene expression. When the suboptimal Kozak sequence of the 1888 AUG was replaced with an optimal one, this reduction was enhanced (64.84%). By increasing the distance between the stop of the overlapping uORF and the core AUG, by a minimum of 15 nucleotides, core/GFP expression was almost doubled, indicating that stalling of ribosomes at the stop of the uORF may be interfering with initiation at the core AUG through steric hindrance. Our findings indicate that the G1888A mutation, may interfere with initiation at the downstream 1901 core AUG, decreasing core protein translation. This decrease may account for the relatively low viral loads seen in individuals infected with subgenotype A1.

Natural history of chronic hepatitis B in Euro-Mediterranean and African countries

Data derived from population, case-control, and cohort studies conducted in several Euro-Mediterranean and African countries disclose impressive similarities in the age and modes of hepatitis B virus (HBV) transmission and in the prevalence, duration, and outcome of the four phases of the natural history of chronic infection. Perinatal HBV infection is rare while the vast majority of chronic infections originate from horizontal HBV transmission to infants and children. HBeAg loss and seroconversion to anti-HBe occur in a few years time, usually during the second decade of life. HBeAg-negative/anti-HBe-positive chronic hepatitis B (CHB), predominates in these countries being 7-9 times more frequent than HBeAg-positive CHB. The predominance of HBeAg-negative CHB is largely linked to the molecular characteristics of HBV genotype D prevailing in European and African countries of the Mediterranean basin and of genotype E and subgenotype A1 that prevail in the other parts of Africa. The molecular characteristics of the African subgenotype A1 differ from those of European subgenotype A2 explaining the fact that patients infected subgenotype A1 demonstrate an earlier loss of HBeAg and seroconversion to anti-HBe during the natural course of HBV infection compared to those infected with subgenotype A2. It is proposed that the molecular characteristics of HBV genotypes and subgenotypes prevailing in Euro-Mediterranean and African countries acting in concert with host and environmental factors largely determine the natural history of chronic HBV infection and its significant differences from countries of HBV genotype C and B and of subgenotype Ae predominance. The knowledge of the natural history of chronic HBV infection in Euro-Mediterranean and African countries combined with wide screening programs for prompt recognition and treatment of chronic HBV infection both in its HBeAg-positive and -negative immune reactive phases can be expected to increase the efficacy of current and future therapeutic strategies.

Host sphingolipid biosynthesis is a promising therapeutic target for the inhibition of hepatitis B virus replication

Serine palmitoyltransferase (SPT) catalyzes the first step in the sphingolipid biosynthetic pathway. Myriocin inhibits SPT and was shown to suppress the replication of hepatitis C virus (HCV) in vitro and in vivo. However, its effect on hepatitis B virus (HBV) replication is unknown. In this study, the HBV DNA levels in HuH7 cell culture supernatants were lowered successfully by using myriocin and it was found that the 50% inhibitory concentration of myriocin is approximately 5 µM. Myriocin and/or pegylated interferon (PEG-IFN) were also administered to chimeric mice for 2 weeks and the effects of these compounds on HBV DNA levels were determined. Myriocin alone did not reduce effectively the HBV DNA levels, whereas PEG-IFN alone reduced the DNA levels to 1/10th of the control levels. The combination of myriocin with PEG-IFN reduced the HBV levels to about 1/1,000 th of the control levels and induced a 1.0 log reduction in the levels of the HBV surface antigen and core protein. This latter effect was not observed in the other treatment groups. In conclusion, the combination of myriocin with PEG-IFN represses synergistically HBV replication in vivo without inducing hepatotoxicity.

Molecular characterization of hepatitis B virus isolates from Zimbabwean blood donors

Hepatitis B virus (HBV) is endemic in Africa, being hyperendemic in sub-Saharan Africa. Genotypes A, D, and E circulate in Africa, showing a distinct geographical distribution. The aim of the present study was to determine the HBV genotype distribution in blood donors from different geographical locations in Zimbabwe. Using a restriction fragment polymorphism assay, sequencing of the basic core promoter/precore region and of the complete S open reading frame showed that 29 HBV isolates from geographically distinct regions belong to subgenotype A1. The complete genome of two of these Zimbabwean HBV isolates was sequenced. Forty-four percent of the Zimbabwean HBV isolates (11/23) were characterized by a G1862C missense mutation, which causes a Val to Leu amino acid substitution at position 17 of the precore region. The majority of Zimbabwean HBV isolates clustered with a number of South African HBV isolates, with which they shared characteristic amino acids in the preS1, preS2, and polymerase spacer regions. The wide distribution of subgenotype in Africa, as well as the high intragroup divergence and the geographical clustering of the African and Asian subgenotype A1 HBV isolates indicate that this subgenotype has a long period of endemicity in these regions.

Investigating an outbreak of acute viral hepatitis caused by hepatitis E virus variants in Karachi, South Pakistan

Hepatitis E is a classic water-borne disease in developing countries. Detection of anti-HEV IgM and IgG antibodies, in addition to HEV RNA are useful epidemiological markers in diagnosis of hepatitis E. This study was conducted to investigate an outbreak of acute viral hepatitis in South-Pakistan. Anti-HEV IgM and IgG were assessed comparatively with serological kits manufactured by Abbott, Cosmic, TGH, and Wantai, selecting HEV RNA as reference assay. Molecular evolutionary analysis was performed by phylogeny and HEV spread time analysis by Bayesian Coalescent Theory approach. Of the 89 patients, 24 (26.9%) did not have acute hepatitis viral marker. Of the remaining 65 cases, 4 (6.1%) were positive for anti-HAV IgM, one (1.5%) for anti-HBc IgM, 2 (3%) for HCV, 53 (81.5%) for anti-HEV IgM, and 5 (7.7%) were hepatitis-negative. The Wantai test was 100% sensitive and specific followed by Cosmic (98.1% and 100%), TGH (98.1% and 97.2%) and Abbott (79.2% and 83.3%). Two HEV variant strains were detected by phylogeny responsible for this acute hepatitis outbreak. Estimates on demographic history of HEV showed that HEV in Pakistan has remained at a steady nonexpanding phase from around 1970 to the year 2005, in which it expanded explosively with the emergence of new HEV variants. In conclusion, the limited sensitivity of available assay (Abbott anti-HEV EIA) may be a concern in HEV diagnosis in Pakistan. This study cautions that the dissemination of the variant strains to other areas of Pakistan may lead to explosive HEV outbreaks.

Recent advances in the research of hepatitis B virus-related hepatocellular carcinoma: epidemiologic and molecular biological aspects

Hepatocellular carcinoma (HCC) is one of the commonest cancers worldwide, and more than half of HCC patients are attributable to persistent hepatitis B virus (HBV) infections. The best and cheapest way to prevent HBV-related HCC is the implementation of universal hepatitis B vaccination program, by which the incidence rates of childhood HCC have been reduced in several countries, including Taiwan. However, there are still hundreds of millions of HBV carriers in the world that remain a global health challenge. In the past decade, several hepatitis B viral factors such as serum HBV DNA level, genotype, and naturally occurring mutants have already been identified to influence liver disease progression and HCC development in HBV carriers. Several easy-to-use scoring systems based on clinical and viral characteristics are developed to predict HCC risk in HBV carriers and may facilitate the communication between practicing physicians and patients in clinical practice. In addition, the role of nonviral factors in HBV-related HCC has also been increasingly recognized. On the basis of these emerging data, it is recommended that HBV carriers should be screened and monitored to identify those who have a higher risk of liver disease progression and require antiviral treatments. Regarding the molecular carcinogenesis of HCC development, despite some progress in the research of cell biology of HCC in the past decade, aberrant pathways involved in maintaining HCC phenotypes have not been completely elucidated yet. In the future, through comprehensive and integrated approaches to analyze the genomes of human HCC, novel target genes or pathways critically involved in hepatocarcinogenesis may hopefully be identified.

Reactivation of hepatitis B virus following rituximab-plus-steroid combination chemotherapy

Reactivation of hepatitis B virus (HBV) has been reported as a fatal complication following systemic chemotherapy or other immunosuppressive therapy. The risk of HBV reactivation differs according to both the patient's HBV infection status prior to systemic chemotherapy and the degree of immunosuppression due to chemotherapy. For establishing an optimal strategy for hepatitis prevention and treatment, it is necessary to understand the characteristics, the clinical course and the risk factors for HBV reactivation and to recognize the difference between hepatitis B surface antigen (HBsAg)-positive and -negative patients with HBV reactivation. Among the important viral risk factors, HBV-DNA level and HBV-related serum markers have been reported to be associated with HBV reactivation in addition to cccDNA, genotypes and gene mutations. Rituximab-plus-steroid combination chemotherapy has recently been identified as a host risk factor for HBV reactivation in hepatitis B core antibody (anti-HBc)-positive and/or hepatitis B surface antibody (anti-HBs) positive--but nonetheless HBsAg-negative--lymphoma patients. For these patients with resolved hepatitis B, preemptive therapy guided by serial HBV-DNA monitoring is a reasonable strategy to enable early diagnosis of HBV reactivation and initiation of antiviral therapy. In this review, we summarize the characteristics of HBV reactivation following rituximab-plus-steroid combination chemotherapy, mainly in HBsAg-negative lymphoma patients, and propose a strategy for managing HBV reactivation.

A population-based cohort study for the risk factors of HCC among hepatitis B virus mono-infected subjects in Japan

BACKGROUND

There have only been a few prospective studies investigating risk factors associated with the development of hepatocellular carcinoma (HCC) among chronic hepatitis B patients all over the world, and no study has been conducted in Japanese population.

METHODS

A population-based cohort consisting of 19393 subjects (middle aged or older) with over 13 years' follow-up was investigated in Japan.

RESULTS

Of 19393 subjects, 479 had hepatitis B virus (HBV) mono-infection (2.5%). During the 245923 person-years' follow-up (average follow-up period 12.7 years), 13 cases of newly diagnosed HCC were documented in the HBV mono-infected group. Several factors at baseline (male, smoking, alanine aminotransferase, the positivity of HBe antigen and HB core-related antigen, the proportion of HBV DNA ≥ 5 log copies/mL, T1753V mutation, and A1762T/G1764A double mutation) were significantly associated with HCC among HBV mono-infected subjects. Multivariate-adjusted Cox hazard model showed that A1762T/G1764A (hazard ratio 7.05 [95% confidence interval (CI) 1.03-48.12, P = 0.046]) was the only independent risk factor for the development of HCC. Kaplan-Meier method also showed that the probability of HCC occurrence-free was significantly lower in HBV mono-infected subjects with A1762T/G1764A double mutation than those without these mutations.

CONCLUSION

HBV mono-infected subjects with A1762T/G1764A double mutation could be at high risk of HCC development during the natural course of HBV infection.

High prevalence of hepatitis B virus genotype E in Northern Madagascar indicates a West-African lineage

The prevalence of hepatitis B virus (HBV) markers was investigated in 563 inhabitants aged 15-55 years from a sugar cane region, Sirama, and from a village, Mataipako, in Northern Madagascar. Serological markers of past or present infection were significantly higher in Sirama, 74% versus 45%. There was no difference in the prevalence of chronic HBsAg carriers, 8.7% versus 8.5% between the two regions. Sequencing the S gene in 45 strains revealed a predominance of genotype E, in 53%, followed by subgenotype A1 in 22%, and genotype D in 18%. Phylogenetic analyses of the genotype E strains showed homology with West African strains. All A1 isolates were similar to Malawi strains. Most genotype D strains were subgenotype D7 and related to strains from Somalia and Tunisia. One genotype D strain formed a branch between Pacific D4 and African D7 strains at neighbor-joining analysis. The pre-core stop mutant was found in 33% of the genotype D strains, 17% of E but not in any A1 strain. The high prevalence and low variability of genotype E strains in only two villages, indicates a rather recent introduction of this genotype into Madagascar from West Africa, possibly through migration or slave trade. The wider spread and genetic relationship of genotype D with East African and Austronesian strains indicate an earlier introduction of this genotype. Molecular epidemiology of HBV may thus be used to complement linguistic and genetic studies on past human migrations in Africa.

[Symptoms of hepatocellular carcinoma. Laboratory tests used for its diagnosis and screening]

Early stage hepatocellular carcinoma is a symptom-free disease. Local and general symptoms occur due to the growth of the tumor tissue and the infiltration of the surrounding blood vessels. Illness progression is indicated by the development of abdominal discomfort, cachexia, therapy-resistant decompensation of previously compensated cirrhosis and in severe cases, the thrombosis of the portal vein or the hepatic veins. Characteristic laboratory findings are the quickly deteriorating blood and liver function tests results, the occurrence of haemostatic disorders and occasional hypoglycemia and/or hypercalcemia. To clarify the etiology and to identify high risk patients, we need to differentiate alcohol-, drug- or chemical-induced hepatic disorders, viral hepatitis B, C and Delta, metabolic disorders and non-alcoholic steatohepatitis. In the case of focal hepatic lesions, persistently elevated alfa fetoprotein levels have a high diagnostic value. At levels over 200 ng/ml, the positive predictive value is >90%. Other, less commonly measured biomarkers are the glycosilated alfa fetoprotein-L3 and the vitamin K-deficiency induced des-gamma-carboxy prothrombin. The risk of tumor occurrence is multiple in patients with HbeAg positive chronic hepatitis B if the virus is of genotype C with mutations in the 1762 and 1764 locations of the core promoter region. Abdominal ultrasound and measurement of alfa fetoprotein is recommended every 6 months for high risk individuals, or every 3-4 months over an 18-24 months period for patients with hepatic lesions of <1cm and of unknown malignancy.

Hepatitis B virus BCP, Precore/core, X gene mutations/genotypes and the risk of hepatocellular carcinoma in India

The study aims to characterize mutations of the HBV genome involving BCP, Precore/core and X regions and also defines HBV genotypes in patients of hepatocellular carcinoma (HCC). The study involved 150 HBV-related HCC cases and 136 HBV-related chronic liver disease patients without HCC as controls. HBV DNA was subjected to mutational analysis using SSCP technique, genotyping by RFLP, and direct nucleotide sequencing. HBV DNA was found in 58.7% (88/150) of the HCC cases and 74.3% (101/136) of controls. HBV mutants were observed in 44.3% of HCC cases and 43.2% of controls. HBV/D was prevalent amongst the patients and controls, followed by HBV/A. The prevalence of the TT1504 mutation in the X gene, the V1753 and T1762/A1764 mutations in the BCP region, and G1914 mutation in the core gene were significantly higher in the HCC group than in the non-HCC group. Multivariate analyses showed that the TT1504, V1753, A1762T/G1764A, and the G1914 mutations and the patient's age, sex, and HBeAg status increased the risk of HCC development significantly. Also, patients with HCC had lower levels of serum albumin, viral load, and platelet counts but higher values of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, and Alpha feto-protein than those of controls (P < 0.001 for all comparisons). HBV/D was the predominant genotype associated with HCC cases seen in India. The presence of different types of HBV mutations, age, sex, HBeAg status, and viral load was found to increase significantly the risk of HCC development in India.

[Direct cytopathic effects of particular hepatitis B virus genotypes in immunosuppressive condition]

Little is known about the direct cytopathic effect of hepatitis B virus (HBV) and its association with particular viral genotype or genetic mutation. In some immunosuppressed chronic HBV patients who had liver transplantation or HIV-coinfection, high viremia and liver fibrosis may occur. These findings suggest that hepatic injuries could arise in the absence of a mature immune system and the difference of genotype and/or specific mutation would affect cytopathic potential of the virus. We investigate HBV genotype-related differences in viral replication, antigens expression and histopathology using in vitro replication model or uPA/SCID mice harboring human hepatocytes, demonstrating that different HBV genotypes and even particular mutation are associated with different virological and histopathological characteristics. Infection with HBV/C2 as well as PC mutant of the HBV/B1 in immunosuppressive conditions can induce direct cytopathic effect in "humanized" part of the murine liver.

Mechanisms of HBV-related hepatocarcinogenesis

The hepatitis B virus (HBV) is a small enveloped DNA virus, which primarily infects hepatocytes and causes acute and persistent liver disease. Epidemiological studies have provided overwhelming evidence for a causal role of chronic HBV infection in the development of hepatocellular carcinoma, but the molecular mechanisms underlying virally-induced tumourigenesis remain largely debated. In the absence of a dominant oncogene encoded by the HBV genome, indirect roles have been proposed, including insertional activation of cellular cancer-related genes by HBV DNA integration, induction of genetic instability by viral integration or by the regulatory protein HBx, and long-term effects of viral proteins in enhancing immune-mediated liver disease. Recent genetic studies indicate that HBV-related tumours display a distinctive profile with a high rate of chromosomal alterations and low frequency of beta-catenin mutations. This review will discuss the evidence implicating chronic HBV infection as a causal risk factor of primary liver cancer. It will also discuss the molecular mechanisms that are critical for the tumourigenic process due to long lasting infection with HBV.

Molecular evolutionary analysis and mutational pattern of full-length genomes of hepatitis B virus isolated from Belgian patients with different clinical manifestations

Molecular evolutionary patterns of 62 HBV full-length genomes obtained from Belgian patients were characterized. Phylogenetic analysis revealed diverse HBV subgenotypes including A2 and A6 (46.8%), D1-D4 (38.8%), E (9.7%), C1 (1.6%), and B2 (1.6%). The study population consisted of patients with different ethnic origin (Caucasian, Turkish, Asian, Arab, and African). One HBV D/C recombinant isolate was identified, which encoded subtype adw2. An HBV subgenotype D4 with an aberrant subtype ayw4 was detected. Although none of the genotypes was associated with a specific disease outcome, several nucleotide substitutions, deletions and insertions were observed within the HBV preS1/S and X genes, particularly among patients with active chronic hepatitis B infection and patients with cirrhosis. Within the immunological domain of the HBsAg gene, the most frequent substitutions were sT125M and sT118A. High rates of precore and basal core promoter mutations were detected in patients infected with genotype D of HBV. Almost half of the patients who received lamivudine therapy for at least 1 year had HBV variants associated with lamivudine drug resistance. In conclusion, the most common HBV genotypes in West Europe (A and D) also prevail in Belgium. The highest degree of genetic diversity was detected in HBV genotype D. In addition, this study reveals the circulation of exotic HBV genotypes B, C, and E in Belgium. J. Med. Virol. 82:379-389, 2010. (c) 2010 Wiley-Liss, Inc.

Subgenotypes of hepatitis B virus genotype D (D1, D2, D3 and D5) in India: differential pattern of mutations, liver injury and occult HBV infection

Hepatitis B genotype D (HBV/D) is the most widespread genotype and exists as at least five subgenotypes (HBV/D1-D5). However, little is known about the association of virological characteristics with clinical differences among HBV/D subgenotypes. To investigate the virological characteristics of these subgenotypes and their clinical implications, we selected a cohort of 109 genotype D infected individuals from the state of West Bengal, India, including 68 HBsAg positive patients and 41 with occult HBV infection. Among the HBsAg positive subjects 28 had chronic hepatitis B virus infection, 40 were asymptomatic carriers based on clinical examination, liver function test and ultrasonograph results. Overall, HBV/D1 was found in 17%, HBV/D2 in 29%, HBV/D3 in 34% and HBV/D5 in 20% of the cases. HBV/D1 was significantly associated with chronic liver disease (P = 0.01), and in this subgenotype A1896 (PreC mutations) were most common. Although BCP mutations (A/C1753 and T1762/A1764) were found to be frequently associated with HBV/D2 (33% and 33%) and D5 (47% and 59%), no apparent clinical correlation was observed. On the other hand, occult HBV infection was significantly associated with HBV/D3 infection, along with low level of BCP and PreC mutations and several non-synonymous substitutions in the catalytic reverse transcriptase (RT) domain of polymerase gene. Similar nucleotide substitutions in the surface (S) gene region were observed from both northern and eastern Indian HBV/D3 isolates. In conclusion, HBV/D subgenotypes differ in their mutational patterns in the S, polymerase and the BCP/PreC regions that may influence their clinical outcomes.

Hepatitis B viral loads in southern African Blacks with hepatocellular carcinoma

Although viral loads are known to influence the development of hepatitis B virus-induced hepatocellular carcinoma in a number of populations, little information is available in the Black African population. Black African patients with hepatocellular carcinoma differ from those in other populations in having a lower frequency of e antigen-positivity and in other respects that might affect viral loads. Hepatitis B viral loads were measured using real-time polymerase chain reaction assay in 124 Black Africans with hepatocellular carcinoma and compared with those in 125 Black adult asymptomatic viral carriers. The geometric mean viral load in the cancer patients was 553,618 copies/ml (95% CI 301,953-1,015,033 copies/ml), with 62.1% having loads >1 x 10(5) copies/ml and 87.1% >1 x 10(4) copies/ml, whereas that in the carriers was 16,084 copies/ml (95% CI 9,184-28,168 copies/ml), with only 15.2% having values >1 x 10(5) copies/ml and 49.6% >1 x 10(4) copies/ml (P < 0.001 in each instance). Mean viral load was significantly higher in e antigen-positive than e antigen-negative cancer patients (5,905,357 copies/ml [1,362,847-25,588,520] cf 238,173 copies/ml [97,200-685,730]: P < 0.001) after adjusting for age and sex. No statistically significant difference existed between patients in different age groups, in men and women, or in patients infected with genotype A or D after adjusting for the other variables.

CONCLUSION

Black Africans with hepatocellular carcinoma have high hepatitis B viral loads in spite of the relative infrequency of e antigen-positivity.

Epidemic spread of hepatitis C virus genotype 3a and relation to high incidence of hepatocellular carcinoma in Pakistan

Studies conducted in different populations worldwide revealed an association between HCV genotype 1 and the development of hepatocellular carcinoma (HCC) than in infection with other HCV genotypes. There are reports which reveal the association of HCV genotype 3a (HCV-3a) with hepatic steatosis and fibrosis but its relation with the development of HCC has not been investigated. In Pakistan, where the incidence of HCC is increasing, 189 patients with chronic liver disease including 82 with HCC were enrolled. HCV genotypes were determined by phylogeny in the NS5B region and the epidemic history of HCV-3a was examined using coalescent theory based methods. HCV-3a was the predominant genotype (81.4%) in the cohort studied, followed by 3b (9.3%), 3k (2.3%), 1a (1.5%), 1c (1.5%), 1b (0.8%), and 2a (0.8%) where 76% of HCC and 86% of non-HCC were infected with HCV-3a. The significant factors associated with HCC were older age (mean +/- SD) 55.8 (+/-9.9) (P < 0.0001), and male gender (P < 0.001). HCV RNA was significantly higher in patients with HCC and chronic hepatitis than in liver cirrhosis (P < 0.0001). Molecular evolutionary analysis revealed a distinct phylogenetic cluster of HCV-3a in Pakistan and an estimation of the effective number of HCV infections indicated the appearance of HCV-3a in this region around 1920s and a rapid exponential growth in the 1950s. This indicates that the epidemic spread of HCV-3a occurred earlier in Pakistan than in other countries in which this genotype has been reported. HCV-3a which spread earlier in Pakistan may be associated with an increasing incidence of HCC.

Case-control study for the identification of virological factors associated with fulminant hepatitis B

BACKGROUND

Host and viral factors can promote the development of fulminant hepatitis B (FHB), but there have been no case-control studies for figuring out virological parameters that can distinguish FHB.

METHODS

In a case-control study, virological factors associated with the development of FHB were sought in 50 patients with FH developed by transient hepatitis B virus (HBV) infection (FH-T) and 50 with acute self-limited hepatitis B (AHB) who were matched for sex and age. In addition, 12 patients with FH developed by acute exacerbation (AE) of asymptomatic HBV carrier (ASC) (FH-C) were also compared with 12 patients without FH by AE of chronic hepatitis B (AE-C).

RESULTS

Higher HBV DNA levels, subgenotype B1/Bj, A1762T/G1764A, G1896A, G1899A and A2339G mutation were significantly more frequent (P < 0.05), while hepatitis B e-antigen was less frequent in the FH-T patients than AHB. In multivariate analysis, G1896A mutation (odds ratio [OR], 13.53; 95% confidence interval [CI], 2.75-66.64), serum HBV DNA more than 5.23 log copies/mL (OR, 5.14; 95% CI, 1.10-24.15) and total bilirubin more than 10.35 mg/mL (OR, 7.81; 95% CI, 1.77-34.51) were independently associated with a fulminant outcome by transient HBV infection. On the other hand, in comparison with the patients between FH-C and AE-C groups, there was no significant difference of virological factors associated with the development of FHB.

CONCLUSION

A number of virological factors have been defined that may distinguish FH-T from AHB in a case-control study. The pathogenic mechanism of FHB between transient HBV infection and AE of ASC would be different.

Distribution of hepatitis B virus genotypes among patients with chronic infection in Japan shifting toward an increase of genotype A

Acute hepatitis B virus (HBV) infection has been increasing through promiscuous sexual contacts, and HBV genotype A (HBV/A) is frequent in patients with acute hepatitis B (AHB) in Japan. To compare the geographic distribution of HBV genotypes in patients with chronic hepatitis B (CHB) in Japan between 2005 and 2006 and between 2000 and 2001, with special attention to changes in the proportion of HBV/A, a cohort study was performed to survey changes in genotypes of CHB patients at 16 hospitals throughout Japan. Furthermore, we investigated the clinical characteristics of each genotype and examined the genomic characteristics of HBV/A isolates by molecular evolutionary analyses. Of the 1,271 patients, 3.5%, 14.1%, and 82.3% were infected with HBV/A, -B, and -C, respectively. In comparison with our previous survey during 2000 and 2001, HBV/A was twice as frequent (3.5% versus 1.7%; P = 0.02). The mean age was lower in the patients with HBV/A than in those with HBV/B or -C. Based on phylogenetic analyses of 11 full-length genomes and 29 pre-S2/S region sequences from patients, HBV/A isolates were imported from Europe and the United States, as well as the Philippines and India. They clustered with HBV/A from AHB patients and have spread throughout Japan. HBV/A has been increasing in CHB patients in Japan as a consequence of AHB spreading in the younger generation through promiscuous sexual contacts, aided by a tendency of HBV/A to induce chronic hepatitis. The spread of HBV/A infection in Japan should be prevented by universal vaccination programs.

Direct cytopathic effects of particular hepatitis B virus genotypes in severe combined immunodeficiency transgenic with urokinase-type plasminogen activator mouse with human hepatocytes

BACKGROUND & AIMS

Little is known about the direct cytopathic effect of hepatitis B virus (HBV) and its association with particular viral genotypes or genetic mutations. We investigate HBV genotype-related differences in viral replication, antigen expression, and histopathology in severe combined immunodeficiency transgenic with urokinase-type plasminogen activator mice harboring human hepatocytes.

METHODS

Mice were inoculated with wild-type of different genotype strains (3 for each HBV/A2, B1, and C2) recovered from preinfected-mice sera or patient sera.

RESULTS

Histologic analysis of mice infected with HBV/C2 for 22-25 weeks showed abundant ground-glass appearance of the hepatocytes and fibrosis in the humanized part of the murine liver owing to the activation of hepatic stellate cells mediated by oxidative stress through transforming growth factor-beta1 signaling, whereas neither was observed with HBV/A2 and B1. The HBV-DNA level in sera was the highest in mice infected with HBV/C2 compared with those with HBV/A2 and HBV/B1 (10(9), 10(7), and 10(4) log copies/mL, respectively, P < .05) during 6-8 weeks postinoculation. HB core-related antigen excretion had a similar trend among the genotypes, whereas secretion of HB surface antigen was more pronounced for HBV/A2 followed by HBV/C2 and much less for HBV/B1. Introduction of precore stop-codon mutation in the HBV/B1 caused a significant increase in viral replication, antigen expression, and a histopathologic picture similar to HBV/C2.

CONCLUSIONS

By using a humanized in vivo model, we show that different HBV genotypes and even particular mutations resulted in different virologic and histopathologic outcomes of infection, indicating that particular genetic variants of HBV may be directly cytopathic in immunosuppressive conditions.

HBV genotypes in India: do they influence disease severity?

AIMS

Association of HBV genotypes (especially A and D) with severity of liver disease is controversial. We studied the influence of HBV genotypes on liver disease severity among Indian patients.

METHODS

We selected 247 HBV infected patients (42 acute hepatitis, 87 carriers, 44 chronic hepatitis B [CHB], 35 liver cirrhosis [LC] and 40 hepatocellular carcinoma [HCC]). Genotyping of stored sera was performed using genotype-specific enzyme-linked immunosorbent assay (ELISA) and restriction fragment length polymorphism (RFLP). The distribution of genotypes in disease states of differing clinical, histological and biochemical severity were compared.

RESULTS

The most common genotype was D (162/237, 68.3%), followed by A (61, 25.7%) and C (14, 5.9%). The distribution of HBV genotypes between patients with acute hepatitis and CHB (carriers + CHB + LC + HCC), or between carriers and disease states (CHB + LC + HCC), or between mild chronic infection (carriers + CHB) and complications of chronic HBV infection (LC + HCC) was similar. Eighty-seven patients had liver biopsy; the median histological activity index (HAI) and fibrosis stage at baseline were similar between genotype groups (four [1-9] genotype A [n = 28]), three (2-4) genotype C (n = 4) and four (1-10) genotype D (n = 55); P = 0.33 for HAI score; (0.5 [0-6] genotype A, 0.5 [0-4] genotype C and 1 [0-6] genotype D; P = 0.92 for fibrosis stage). The response to therapy was similar between the genotypes.

CONCLUSION

Clinical, histological severity and therapeutic responses are similar among patients with HBV genotypes A and D.

An overview of molecular epidemiology of hepatitis B virus (HBV) in India

Hepatitis B virus (HBV) is one of the major global public health problems. In India, HBsAg prevalence among general population ranges from 2% to 8%, placing India in intermediate HBV endemicity zone and the number of HBV carriers is estimated to be 50 million, forming the second largest global pool of chronic HBV infections. India is a vast country, comprised of multiracial communities with wide variations in ethnicity and cultural patterns, which is attributable to its geographical location, gene influx due to invasion and/or anthropological migrations in the past. Moreover, recent increase in trade, trafficking and use of illicit drugs has also considerably influenced the epidemiology of HBV, specifically in the eastern and north eastern parts of India. However, data on the molecular epidemiology of HBV in India is scanty. HBV genotypes A and D have been well documented from different parts of mainland India. Interestingly, in addition to genotypes A and D, genotype C having high nucleotide similarity with south East Asian subgenotype Cs/C1 strain, have been detected exclusively from eastern Indian HBV carriers, suggesting a recent introduction. Thus, compared to other parts of India, the molecular epidemiology of HBV is naturally distinct in eastern India. Very recently, taking the advantage of circulation of three distinct HBV genotypes within the population of eastern India, different aspects of HBV molecular epidemiology was studied that revealed very interesting results. In this study, the clinical significance of HBV genotypes, core promoter and precore mutations, possible routes of introduction of HBV genotype C in eastern India, the clinical implications of x gene variability, prevalence of the AFB₁ induced p53 gene codon 249 mutation, the transmission potentiality of HBV among asymptomatic/inactive or occult HBV carriers and the genetic variability of HBV persisting in the PBL was investigated. In this manuscript, the information available on the molecular epidemiology of HBV in India has been reviewed and the results of studies among the eastern Indian population have been summarised.

Two simultaneous hepatitis B virus epidemics among injecting drug users and men who have sex with men in Buenos Aires, Argentina: characterization of the first D/A recombinant from the American continent

Previous studies have revealed that hepatitis B virus (HBV)/D and HBV/F predominate among blood donors from Buenos Aires, Argentina. In the present study, blood samples from two high-risk groups were analysed: 160 corresponding to street- and hospital-recruited injecting drug users [81.2% showing the 'anti-hepatitis B core antigen (anti-HBc) only' serological pattern] and 20 to hepatitis B surface antigen (HBsAg)(+)/anti-HBc(+) men who have sex with men. HBV genotypes were assigned by polymerase chain reaction amplification followed by restriction fragment length polymorphism and confirmed by nucleotide sequencing of two different coding regions. HBV DNA was detected in 27 injecting drug users (16.9%, occult infection prevalence: 7.7%), and 14 men who have sex with men (70%). HBV/A prevailed among injecting drug users (81.8%) while HBV/F was predominant among men who have sex with men (57.1%). The high predominance of HBV/A among injecting drug users is in sharp contrast to its low prevalence among blood donors (P = 0.0006) and men who have sex with men (P = 0.0137). Interestingly, all HBV/A S gene sequences obtained from street-recruited injecting drug users encoded the rare serotype ayw1 and failed to cluster within any of the known A subgenotypes. Moreover, one of the HBV strains from a hospital-recruited injecting drug user was fully sequenced and found to be the first completely characterized D/A recombinant genome from the American continent. Data suggest that two simultaneous and independent HBV epidemics took place in Buenos Aires: one spreading among injecting drug users and another one sexually transmitted among the homosexual and heterosexual population.

Clinical significance of precore and core promoter mutations in genotype D hepatitis B-related chronic liver disease

The impact of mutations in the precore and basal core promoter (BCP) regions of the hepatitis B virus on the course of chronic liver disease is not well established. We sought to examine the relationship of these characteristics to the clinical expression of liver disease in patients infected with genotype D chronic hepatitis B (CHB). BCP and precore mutations in 110 patients with genotype D1 CHB were determined and correlated with clinical phenotype. Of 110 patients, 95 (86.5%) were HBeAg-negative. Compared with HBeAg-positive subjects, HBeAg-negative patients were over a decade older and had lower viral loads (3.70 +/- 0.98 vs 5.77 +/- 0.69 log copies/ml, P < 0.001). The double mutation A1762T-G1764A was more prevalent in patients with advanced liver disease (AdLD) and was associated with higher alanine aminotransferase and viral load. After adjusting for age, there was a more than fourfold increase in the risk of AdLD with this mutation (OR = 4.4; 95% CI: 1.13-16.92, P < 0.03). Conversely, the G1757A substitution was associated with protection, being 90% less frequent among patients with AdLD (P = 0.001). The results indicate that in genotype D CHB, the presence of the A1762T-G1764A mutation was associated with more aggressive liver disease while the G1757A substitution was associated with protection from advanced disease.

Genetic Variability of Hepatitis B virus and Response to Antiviral Therapy

Hepatitis B virus (HBV) infection is a global health issue. Effective and individualized treatment of chronic hepatitis B to prevent progression to end-stage liver diseases and hepatocellular carcinoma is needed. HBV can be classified into eight genotypes (A–H) on the basis of genome sequence divergence. In addition, several naturally occurring HBV mutants have also been identified. The epidemiology of HBV genotypes and their implications for response to antiviral therapy have become increasingly recognized. Recent studies suggested that responses to standard interferon treatment in patients with genotype A or B are better than those with genotype C or D; however, conflicting results exist regarding the response to pegylated interferon. The influence of dose and duration on interferon-based therapy remains to be clarified. In addition to genotype, naturally occurring mutations such as precore and core promoter mutations have also attracted much attention, because they have been shown to affect the disease progression of HBV-related chronic liver disease and possibly the response to antiviral therapy. Here, we review the differences in antiviral theraputic response among HBV genotypes and discuss the role of precore or core promoter mutations in response to antiviral therapy.

A valine to phenylalanine mutation in the precore region of hepatitis B virus causes intracellular retention and impaired secretion of HBe-antigen

AIM

Hepatitis B virus (HBV) e antigen (HBeAg) is translated from precore mRNA as a precore/core protein, which is post-translationally modified to give rise to the protein that is secreted into the serum. The G1862T mutation in HBV occurs in the bulge of the encapsidation signal within the pregenomic RNA. When the precore mRNA is translated, this mutation results in a valine to phenylalanine substitution at the -3 position to the signal peptide cleavage site at the amino end of the precursor protein. The aim of this study was to determine whether this mutation could affect HBV replication and/or HBeAg expression.

METHODS

Following transfection of Huh 7 cells, HBV replication was followed using real time polymerase reaction (PCR) and expression of HBeAg expression was monitored using confocal microscopy.

RESULTS

HBV replication was reduced when this mutation was introduced into genotype D but not into genotype A replication-competent constructs. Using mutant HBeAg-expressing plasmids, we demonstrated a 54% reduction in HBeAg secretion relative to the wild type. Confocal microscopy demonstrated that the mutant HBeAg accumulated in the endoplasmic reticulum, endoplasmic reticulum intermediate compartment and Golgi. These aggregates of mutant protein increased in size following treatment of the cells with a proteasome inhibitor, MG132, and had the hallmark features of aggresomes. They attracted ubiquitin, heat shock proteins and proteasomes and were isolated from the cytosol by the intermediate filaments, vimentin and cytokeratin.

CONCLUSION

The formation of aggresomes, as a result of the G1862T mutation, may play a contributory role in HBV-induced liver disease.

Virological and clinical implication of core promoter C1752/V1753 and T1764/G1766 mutations in hepatitis B virus genotype D infection in Mongolia

BACKGROUND AND AIM

The aim of the present study was to reveal virological and clinical features of hepatitis B virus (HBV) genotype D infection.

METHODS

One hundred and twenty-two Mongolian chronic liver disease (CLD) patients infected with HBV were subjected for serological HBV-markers screening and HBV-enzyme immunoassay (EIA) genotyping. Nucleotide sequences were analyzed for 48 HBV/D strains (23 isolated from hepatocellular carcinoma (HCC) and 25 from CLD patients).

RESULTS

Prevalence of hepatitis B e antigen (HBeAg) positivity was low (25.9%) in young patients (< or =30 years old) indicating early HBeAg seroclearance in HBV/D carriers. The T1764/G1766 double mutation was the most common basal core promoter (BCP) mutation (29.2%) and was frequent in HBeAg-negative patients (39.3%). Patients harboring T1764/G1766 mutants exhibited lower HBV-DNA and HBV core antigen (HBcAg) levels than those with wild-type BCP strains (P = 0.024, 0.049, respectively). C1752 and/or V (not T) 1753 mutation was significantly prevalent in HCC patients (HCC vs CLD; 52.2% vs 20%, P = 0.033). T1762/A1764 mutation was detected in 75.0% of HCC patients with high viral load (> or =5 log copies/mL). Precore stop codon mutation A1896 was detected in (70.8%) of HBV/D-infected patients.

CONCLUSIONS

In Mongolians infected with HBV/D, C1752 and/or V1753 mutation was associated with HCC.

Role of viral factors in the natural course and therapy of chronic hepatitis B

Hepatitis B virus (HBV) infection is a global health problem that causes a wide spectrum of liver disease, including acute or fulminant hepatitis, inactive carrier state, chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). The pathogenesis of hepatocyte damage associated with HBV is mainly through immune-mediated mechanisms. On the basis of the virus and host interactions, the natural history of HBV carriers who are infected in early life can be divided into four dynamic phases. The frequency, extent, and severity of hepatitis flares or acute exacerbation in the second immune clearance and/or fourth reactivation phase predict liver disease progression in HBV carriers. In the past decade, hepatitis B viral factors including serum HBV DNA level, genotype, and naturally occurring mutants predictive of clinical outcomes have been identified. The higher the serum HBV DNA level after the immune clearance phase, the higher the incidence of adverse outcomes over time. In addition, high viral load, genotype C, basal core promoter mutation, and pre-S deletion correlate with increased risk of cirrhosis and HCC development. As to the treatment of chronic hepatitis B, patients with high HBV DNA level and genotype C or D infection are shown to have a worse response to interferon therapy. In conclusion, serum HBV DNA level, genotype, and naturally occurring mutants are identified to influence liver disease progression and therapy of chronic hepatitis B. More investigations are needed to clarify the molecular mechanisms of the viral factors involved in the pathogenesis of each stage of liver disease and the response to antiviral treatments.

Variations in the core promoter/pre-core region in HBV genotype C in Japanese and Northern Vietnamese patients

Hepatitis B virus (HBV) subgenotypes Cs (C1) and Ce (C2) are common in East Asia. To investigate the genomic difference of HBV genotype C between two separated regions, 50 subgenotype Cs-infected Vietnamese and 70 subgenotype Ce-infected Japanese patients were enrolled for analysis. The patients were categorized to either a hepatocellular carcinoma group (HCC) or a non-HCC group including liver cirrhosis, chronic hepatitis, and asymptomatic carriers. HBV serology, HBV-DNA level, and variations in core promoter/pre-core region were examined. Phylogenetic analysis based on the full genome sequences and nucleotide sequences partly in the S gene and in the P gene revealed that all Japanese strains (70/70) were subgenotype Ce, and nearly all of the Vietnamese strains (50/51) were subgenotype Cs, excluding one subgenotype C5. C1858 and G1775 were common in the Vietnamese (64% and 40%) but not in the Japanese (0%). The prevalence of C/A1753 in Vietnamese was higher than that in the Japanese (32% vs. 17.1%), however the frequency of A1896 in the Japanese was significantly higher (32.9% vs. 12%, P < 0.05). Most of the Vietnamese patients with HCC had a high level of HBV-DNA, the Japanese HCC had a relatively low level. In the Vietnamese, C/A1753 and C1858 were associated closely with T1762A1764, higher HBV-DNA levels and higher HCC incidence. The multivariate analysis revealed that male, T1653 and C/A1753 were independent risk factors for HCC. The subgenotypes and unique mutations of HBV genotype C in the Vietnamese and Japanese differed, and C/A1753 and C1858 variants might play a role in the pathogenesis of liver disease in Vietnamese patients.

Subgenotypes of hepatitis B virus genotype C do not correlate with disease progression of chronic hepatitis B in Taiwan

BACKGROUND

Hepatitis B virus (HBV) genotype C (HBV/C) has two subgenotypes: HBV/Cs and Ce. The prevalence and clinical implications of subgenotype Cs and Ce in Taiwanese HBV carriers remain unknown.

METHODS

Subgenotypes of HBV/C were determined in 242 Taiwanese HBV carriers with various stages of liver disease. The clinical as well as virologic features between patients with HBV/Cs and HBV/Ce infection were further compared.

RESULTS

HBV/Ce was the predominant subgenotype in Taiwan. The prevalence of HBV/Ce was 93.6% in the inactive carriers group, 84.2% in chronic hepatitis patients, 81.2% in cirrhosis patients, 92.5% in hepatocellular carcinoma (HCC) patients without cirrhosis and 91.9% in HCC patients with cirrhosis. There was no significant difference in the distribution of the HBV/C subgenotypes among patients with different stages of liver disease.

CONCLUSIONS

Subgenotypes of HBV/C may not have a clinical impact on the disease progression of chronic hepatitis B in Taiwan.

Viral genotype and baseline load predict the response to adefovir treatment in lamivudine-resistant chronic hepatitis B patients

BACKGROUND/AIMS

To determine the factors associated with virological response (VR), HBeAg loss or the emergence of adefovir (ADV)-related mutations in ADV-treated chronic hepatitis B (CHB) patients with lamivudine (LAM) resistance.

METHODS

Fifty-four LAM-resistant CHB patients (46% HBeAg-positive) were treated with ADV monotherapy (n=28) or ADV plus LAM (n=26) for a mean of 30.4 months.

RESULTS

Thirty-eight patients (70.4%) achieved VR defined as HBV-DNA levels <10(4)copies/ml within the first 12 months of treatment. Six (24%) of 25 HBeAg-positive patients exhibited HBeAg loss and 20% seroconverted to anti-HBe. Eight patients (14.8%) developed ADV-related mutations. In the multivariate analysis, female gender (HR=0.20, 95% CI: 0.05-0.76, p=0.018), HBeAg-negative (HR=0.37, 95% CI: 0.14-0.96, p=0.040) and low baseline HBV-DNA levels (HR=0.65, 95% CI: 0.45-0.95, p=0.027) were independent predictors of VR, whereas low HBV-DNA levels (HR=0.36, 95% CI: 0.11-1.20, p=0.095) and HBV-genotype D (HR=0.06, 95% CI: 0.004-0.84, p=0.037) independently predicted HBeAg loss.

CONCLUSIONS

ADV therapy suppresses viral replication in more than 70% of LAM-R patients. Factors associated with virologic response are female gender, HBeAg-negative status and low baseline serum HBV-DNA levels. Genotype D HBV infection and low baseline HBV-DNA levels independently predict HBeAg loss.

Hepatitis B virus genotypes in Europe

There are eight genotypes of hepatitis B virus (HBV). Most genotypes can be further divided into subgenotypes. HBV genotypes influence the course of disease and treatment, and show geographic preferences. In Europe, A and D are the main genotypes found. Genotype A is more prevalent in northern Europe, where genotype D is mainly found in countries surrounding the Mediterranean Sea and in Eastern Europe. Subgenotype A2 is the dominant subgenotype in Europe, but the geographic prevalence of the four subgenotypes found in genotype D is not yet clear. On treatment with interferon HBV, genotype A, compared to genotype D, showsbetter virological response and in a large proportion of patients, even development of anti-HBs. However, in the first year of treatment with lamivudine, higher rates of emergence of YMDD variants are observed in genotype A. This work summarizes the current knowledge on HBV genotypes in countries with low and intermediate HBV carriership from Europe.

Molecular characterization of subgenotype A1 (subgroup Aa) of hepatitis B virus

Subgenotypes of hepatitis B virus (HBV) were first recognized after a unique segment of genotype A was identified when sequencing the preS2/S region of southern African HBV isolates. Originally named subgroup A', subsequently called subgroup Aa (for Africa) or subgenotype A1, this subgenotype is found in South Africa, Malawi, Uganda, Tanzania, Somalia, Yemen, India, Nepal, the Philippines and Brazil. The relatively higher mean nucleotide divergence of subgenotype A1 suggests that it has been endemic and has a long evolutionary history in the populations where it prevails. Distinctive sequence characteristics could account for the high hepatitis B e-antigen (HBeAg) negativity and low HBV DNA levels in carriers of this subgenotype. Substitutions or mutations can reduce HBeAg expression at three levels: (i) 1762T1764A atthe transcriptional level; (ii) substitutions at nt 1809-1812 at the translational level; and (iii) 1862T at the post-translational level. Co-existence of 1762T1764A and nt 1809-1812 mutations reduces HBeAg expression in an additive manner. In addition, subgenotype A1 has unique sequence alterations in the transcriptional regulatory elements and the polymerase coding region. The distinct sequence characteristics of subgenotype A1 may contribute to the 4.5-fold increased risk of heptocellular carcinoma in HBV carriers infected with genotype A, which is entirely attributable to subgenotype A1.

Epidemiology of hepatitis B virus in Africa, its genotypes and clinical associations of genotypes

Of approximately 360 million people in the world chronically infected with hepatitis B virus (HBV), 65 million reside in Africa. Thus, Africa, with 12% of the world's population, carries approximately 18% of the global burden of HBV infection, with hepatocellular carcinoma and cirrhosis accounting for 2% of the continent's annual deaths. Despite HBV being endemic or hyperendemic in Africa, there is a paucity of data on the genotypes and their distribution. Genotype A is found mainly in southern, eastern and central Africa. Most African genotype A strains belong to subgenotype A1, with subgenotype A3 found in western Africa. Genotype D prevails in northern countries and genotype E in western and central Africa. Ithas become increasingly evident that heterogeneity in the global distribution of HBV genotypes may be responsible for differences in the clinical outcomes of HBV infections and the response to antiviral treatment and vaccination. A limited number of studies have been published relating genotypes to clinical outcomes in African countries. Because observations from other regions of the world can not be extrapolated from one locale to another, the HBV strains circulating in Africa should be studied and related to clinical outcomes.

Distribution and characteristics of hepatitis B virus genotype C subgenotypes in China

Genetic diversity within the same hepatitis B virus (HBV) genotype indicates the presence of several subgenotypes. We have found that genotype C is the most common in China, and this study aimed to determine the geographical distribution and characteristics of HBV-C subgenotypes in the country. A cohort of 534 patients with chronic HBV genotype C infection, collected across China, was analysed by nucleotide sequencing or polymerase chain reaction-restriction fragment length polymorphism. HBV-C1/Cs (n = 112, 21%) and HBV-C2/Ce (n = 397, 74%) were the most common HBV-C subgenotypes and showed different geographical distribution in China. No significant differences were found between patients infected with HBV-C1 and HBV-C2 when comparing liver function tests, hepatitis B e antigen positive rate and clinical manifestations. We identified two other types of HBV-C provisionally designated as HBV-CD1 and HBV-CD2, which have particular virological features and clustered in one geographic area. These two types of C/D hybrids have emerged through recombination with genotype D and encode serotype ayw2 hepatitis B surface antigen. In conclusion, there are at least four subtypes of HBV genotype C: subgenotypes C1, C2 and two types of C/D recombinants CD1 and CD2 in China, which have a distinct geographic distribution. Whether HBV-C subgenotypes differ in their impact on liver disease progression requires prospective studies.

Early dynamics of hepatitis B virus in chimeric mice carrying human hepatocytes monoinfected or coinfected with genotype G

Of the 8 genotypes of HBV (genotypes A-H), genotype G is unique in that it has an insertion in the core gene and two stop codons in the precore region preventing the synthesis of hepatitis B e antigen. Most individuals with genotype G are coinfected with other genotypes, typically genotype A. Mice with severe combined immunodeficiency disease carrying human hepatocytes were infected with HBV particles propagated in Huh7 cells in culture. Mice monoinfected with genotype G did not raise detectable HBV DNA in serum, although products of the core gene emerged 4 to 8 weeks after inoculation. When they were superinfected with genotype A at week 10, however, HBV DNA of genotype A developed, which was replaced almost completely by that of genotype G within 10 weeks. Such a rapid takeover was also observed in mice initially infected with genotype A or C and superinfected with genotype G. Similar viral dynamics occurred in mice simultaneously coinfected with genotypes G and A. Takeover was markedly enhanced in mice inoculated with a serum passage containing genotype G with a trace of genotype A. Coinfection of mice with genotypes G and A induced abundant cellular steatosis along with increased fibrosis in the liver, which was not detected in mice monoinfected with genotype A or G.

CONCLUSION

Genotype G can monoinfect chimeric mice at very low levels, and its replication increases maredly when coinfected with other genotypes. Coinfection with genotype G could enhance fibrosis under immunocompromised states.

A weak association between occult HBV infection and non-B non-C hepatocellular carcinoma in Japan

BACKGROUND

In Japan, approximately 10% of hepatocellular carcinoma (HCC) patients are negative for both hepatitis B surface antigen (HBsAg) and antibodies to hepatitis C virus (anti-HCV), i.e., they constitute the so-called category of non-B non-C (NBNC) HCC. Little is known about the characteristics of NBNC-HCC.

METHODS

Potential risk factors for carcinogenesis (including occult HBV infection [HBsAg is negative but HBV DNA is positive by polymerase chain reaction (PCR)], obesity, and diabetes) were assessed in 233 HCC patients grouped according to hepatitis virus serological status (152 with HCV-HCC, 36 with HBV-HCC, and 45 with NBNC-HCC).

RESULTS

The prevalence of patients with obesity or diabetes was significantly higher in the NBNC-HCC group than in the HBV-HCC group. The same trend was observed even when patients with massive alcohol intake were excluded from the analysis. Only 8 patients (18%) in the NBNC-HCC group had detectable serum HBV DNA, and this was at very low levels (HBV/Ce/C2 and HBV/D were determined in 7 and 1 patients, respectively). In the NBNC-HCC group, the determined nucleotide sequences of the enhancer II/core promoter/precore/core region did not contain any HCC-associated mutations, whereas 25 of 30 patients in the HBV-HCC group carried strains with C1653T, T1753V, and/or A1762T/G1764A mutations.

CONCLUSIONS

A weak association between occult HBV infection and HCC development was observed in the NBNC patients. This study indicates that nonalcoholic steato-hepatitis should be further investigated to assess its contribution to HCC development in this category of patients.

Advances in the researches on hepatitis B virus genotyping and its clinical significance

The genotyping of hepatitis B virus (HBV) is a highlight of the studies associated with chronic hepatitis B inside and outside the country nowadays. HBV infection can lead to chronic carriage of the virus and progressive liver disease, including liver cirrhosis and hepatocellular carcinoma. The serological heterogeneity of HBsAg has been well established. HBV isolates have been classified into 10 different subtypes according to the antigenic determinants of their HBsAg. However, the classification of HBV by serologic subtyping is not rational because a single point mutation at the S gene may result in a change in subtype. Therefore, worldwide HBV isolates have been classified into eight genotypes: A, B, C, D, E, F, G and H, based on the comparison of complete HBV genomes, which is the gold standard for genotyping. The eight genotypes have a distinct characteristic geographical distribution and an HBV genotypic difference in HBV pathogenicity. It has been reported that there are remarkable differences in the clinical and virologic characteristics between the patients with different genotypes. Studies have revealed the association of HBV genotypes with the severity and outcome of chronic liver disease, but the results including the influence of genotypes on therapeutic responses are not consistent.

Clinical and virological characteristics of hepatitis B virus subgenotypes Ba, C1, and C2 in China

Hepatitis B virus (HBV) subgenotypes Ba, C1 (Cs), and C2 (Ce) are the most prevalent HBV variants in China. To investigate the virological characteristics of these subgenotypes and their clinical implications, we enrolled a cohort of 211 patients in the Guangdong Province of China, including 132 with chronic hepatitis B virus infection (CH), 32 with liver cirrhosis (LC), and 47 with hepatocellular carcinoma (HCC) according to clinical examination, liver function test, and ultrasonograph results. Overall, HBV Ba was found in 51.2% (108/211), HBV C1 in 33.6% (71/211), and HBV C2 in 15.2% (32/211) of the cases. The distribution of HBV genotype C was greater among patients in the LC and HCC groups than among patients in the CH group, while the distribution of HBV genotype B was greater among the CH patients than among the LC and HCC patients. No significant differences in clinical features were found among patients with HBV Ba, C1, and C2. Virologically, HBV C1 had the strongest association with the A1762T G1764A double mutation, while the mutation at position 1896 resulting in A (1896A) was uncommon. In contrast, HBV Ba had the highest frequency of 1896A but the lowest of A1762T G1764A, and HBV C2 had intermediate frequencies of these mutations. Mutations of 1653T and 1753V were specifically associated with HBV C2 and C1, respectively. Multivariate analyses showed that the 1653T, 1753V, and A1762T G1764A mutations and patient age significantly increased the risk of HCC development. In conclusion, HBV Ba, C1, and C2 have different mutation patterns in the enhancer II/core promoter/precore region. Therefore, genotyping and detecting the 1653T and 1753V mutations, in addition to the A1762T G1764A double mutation, might have important clinical implications as predictive risk factors for hepatocarcinogenesis.

G1862T mutation among hepatitis B virus-infected individuals: association with viral genotypes and disease outcome in Kolkata, Eastern India

OBJECTIVE

To study the prevalence of G1862T mutation in hepatitis B virus (HBV) isolates among Eastern Indian patients and its relationship with genotypes, HBeAg status and disease manifestation.

METHODS

HBV DNA was isolated from patients, amplified by nested PCR and sequenced directly.

RESULTS

Of the 102 patients, 32 were HBeAg positive and 70 HBeAg negative; 55, 24 and 23 isolates were infected with genotypes D, A and C, respectively. G1862T was detected in 18 samples, 15 (83%) of them belonged to genotype A (subgenotype HBV/A1), 3 (17%) to genotype D. This mutation was more frequent in HBeAg-negative than in HBeAg-positive patients (21 vs. 9%), whereas in HBV/A1 it was as common in HBeAg-positive as in HBeAg-negative patients and significantly associated with T1762/A1764 mutation. The mean viral load was lower in patients with G1862T mutation. Furthermore, this mutation was common in various clinical outcomes.

CONCLUSION

In our community, G1862T mutation was predominantly found in HBV/A1 isolates irrespective of HBeAg status. Moreover this mutation could not be correlated to the clinical outcome. These findings indicate that the G1862T mutation is probably a part of the natural variability of HBV/A1.

Predominance of hepatitis B virus genotype C among Karens, the 'old settlers' of Andaman and Nicobar Islands, India

The Karens, or 'old settlers', migrated from Myanmar to Andaman and Nicobar islands 80 years ago. A high HBV exposure rate among them has been reported. A study of 34 HBsAg carriers was done to investigate the origin of HBV infection among the Karens. RFLP-based genotyping was confirmed by sequencing and phylogenetic analysis. The predominance of HBV/C1/Cs suggests that they carried HBV during their migration, retained it, and in addition, acquired HBV/D2 from the people of mainland India. The reported association of HBV genotype C with disease severity thus warrants further epidemiological investigations among them and on possible spread among neighboring settlers.

High frequency of hepatocellular carcinoma in Mongolia; association with mono-, or co-infection with hepatitis C, B, and delta viruses

To investigate the association between viral infection pattern and hepatocellular carcinoma (HCC), 292 chronic hepatitis patients, including 108 with developed HCC were screened using serological and molecular genetics methods. Viral etiology was established in 267 (91.4%), anti-HCV detected in 198 (67.8%), and HBsAg in 124 (42.5%) including 93 (74.4%) cases with HDV co-infection. HCV mono-infection predominated in both, "non-HCC" and "HCC" groups (54% and 39%, respectively) with higher frequency in the first group (P = 0.011), whereas HBV in co-infection with HDV was more frequent in HCC group (14% vs 25%, P = 0.017). Patients with HCV mono-infection were older than those with co-infection (P<0.02), had higher frequency of HCV-viraemia (82% vs 7%, P < 0.0001), and yet had significantly lower prevalence of HCC (29.6% vs. 49.1%, P = 0.003). Alpha-fetoprotein (AFP) and protein induced by vitamin K antagonist-II (PIVKA-II) were specifically elevated in 71% of HCC patients. In conclusion, although HCV monoinfection pattern predominates in Mongolia, co-infection with HBV and HDV had stronger association with HCC development at younger age. Liver tumor markers; AFP and PIVKA-II are useful tools for complex HCC-screening and clinical follow-up for chronic hepatitis patients in Mongolia.

Virological features of hepatitis B virus-associated nephropathy in Japan

Hepatitis B virus (HBV)-associated nephropathy is considered as an immune-mediated disorder which is dependent on interactions between viral, host, and environmental factors. But there are few reports that investigated the relationship between the development of HBV-associated nephropathy and HBV genotypes and the mutations. To clarify the relationship between nephropathy and HBV genotype in Japan, six male patients with HBV-associated nephropathy were examined. The complete genome sequences of HBV were determined directly and the specific mutations associated with the development of HBV-associated nephropathy were examined by comparison of the alignments along with consensus sequences [HBV/A1 (Aa), A2 (Ae), B1 (Bj), B2 (Ba), C1 (Cs) and C2 (Ce)] retrieved from international database. The mean age of the six patients was 33.5 years. HBeAg was found in all patients and serum HBV-DNA levels were relatively high. Histological findings of renal tissues indicated five cases of membranous nephropathy and one membranoproliferative glomerulonephritis. HBV genotypes from the six patients were two HBV/A1, two A2 and two C2, suggesting HBV/A was predominant. G1862T mutation was observed in the two HBV/A1 patients, resulting in the pre-core amino acid substitution with a switch from valine (Val) to phenylalanine (Phe). Only one patient had core deletions. It is concluded that HBV/A may be associated with membranous nephropathy, but little relationship between HBV gene mutations and the development of HBV-associated nephropathy was observed.

Heterogeneity of Hepatitis B Virus Genotype D in Japan

OBJECTIVE

Hepatitis B virus (HBV) genotypes B and C are predominant in Japan. Previously, we reported that approximately 9% of HBV carriers in the Ehime area of western Japan were infected with genotype D (HBV/D) and their sequences closely related. Recently, serum samples from 3 patients with chronic HBV/D infections living in Tokyo and the surrounding area became available for testing. The purpose of this study was to determine whether the HBV/D isolates from these different areas of Japan are closely related.

METHODS

Of the 3 Tokyo area patients infected with HBV/D, 2 had chronic hepatitis, and 1 had hemophilia with a history of frequent coagulation factor injections. The complete HBV/D genome sequences of each were determined, and compared with those of subjects from the Ehime area.

RESULTS

All 3 HBV/D sequences had a genomic length of 3,182 bases, and the hepatitis B surface antigen subtype was ayw3. Phylogenetic analysis revealed that the 1 of the HBV/D isolates was closely related to the isolates from Ehime Prefecture, while 1 was similar and 1 was clearly distinct.

CONCLUSION

Our results indicate that HBV/D infections in Japan are heterogeneous.

Difference of hepatitis B virus genotype distribution in two groups of mexican patients with different risk factors. High prevalence of genotype H and G

BACKGROUND

Hepatitis B virus (HBV) has been classified in eight genotypes, from A to H (HBV/A to HBV/H). HBV genotypes were determined in two groups with different risk factors.

METHODS

Group I consisted of 42 patients with chronic and acute hepatitis and group II with 25 men who have sex with men (MSM). HBV genotypes were determined by DNA sequencing of the S-gene.

RESULTS

Both groups differed with respect to genotype distribution (p < 0.001). In group I, there were 31 (74%), 9 (21%) and 2 patients (5%) with HBV/H, HBV/D and HBV/A; respectively. In group II, HBV/H, HBV/A, and HBV/G were found in 13 (52%), 8 (32%) and 4 (16%) cases, respectively. By using an HBV/G-specific PCR, 3 more cases of HBV/G were identified in group II, rising to a total 28%. All HBV/G strains were present in coinfection with other HBV genotypes, 86% with HBV/H, and 14% with HBV/A.

CONCLUSIONS

HBV/H predominated in both groups. A high frequency of HBV/G was found in MSM, which was always coinfected with HBV/H or HBV/A. Significant differences in HBV genotype distribution were also found, since HBV/D was present only in patients with liver disease, whereas HBV/G was present only in MSM.