Clinical relevance and public health significance of hepatitis B virus genomic variations

Association between the various mutations in viral core promoter region to different stages of hepatitis B, ranging of asymptomatic carrier state to hepatocellular carcinoma

OBJECTIVES

The objective of this study was to determine the association of 19 mutations with frequencies ≥ 10% in the core promoter region of hepatitis B virus (HBV) with chronic hepatitis B (CHB), liver cirrhosis, and hepatocellular carcinoma (HCC).

METHODS

Eight hundred forty-six asymptomatic hepatitis B surface antigen carriers (ASCs), 235 CHB patients, 188 cirrhosis patients, and 190 HCC patients with intact data of HBV genotyping, DNA sequencing, and serological parameters were studied. Nucleotides with the highest frequencies in HBV genotypes B and C from all ASCs were treated as wild-type nucleotides.

RESULTS

Mutations at nt.1674, nt.1719, nt.1762, nt.1764, nt.1846, nt.1896, and nt.1913 in genotype C were significantly associated with CHB, cirrhosis, and HCC, as compared with ASCs. C1673T, A1726C, A1727T, C1730G, C1766T, T1768A, C1773T, and C1799G in genotype C were significantly associated with cirrhosis compared with the CHB patients, whereas these mutations were inversely associated with HCC compared with the cirrhosis patients. Multivariate regression analyses showed that age, male, abnormal alanine aminotransferase (ALT), T1768A, A1762T/G1764A, and A1846T were independently associated with cirrhosis compared with ASCs and the patients with CHB. Age, abnormal ALT, HBV DNA (≥10(4) copies/ml), genotype C, C1653T, T1674C/G, T1753V, and A1762T/G1764A were independently associated with HCC compared with those without HCC. Haplotypic carriages with two or more HBV mutations were significantly associated with HCC. T1674C/G, C1653T, and T1753V were specific for HCC. A1762T/G1764A had a moderate sensitivity and specificity for HCC.

CONCLUSIONS

C1673T, A1726C, A1727T, C1730G, C1766T, T1768A, C1773T, and C1799G in genotype C are specific for cirrhosis. A1846T and T1674C/G are novel factors independently associated with cirrhosis and HCC, respectively.

A study of genotypes, mutants and nucleotide sequence of hepatitis B virus in Pakistan: HBV genotypes in pakistan

BACKGROUND

Hepatitis B virus (HBV) genotypes and mutations are gaining importance in determining the clinical course of chronic liver disease.

OBJECTIVES

To determine and compare the distribution of HBV genotypes and genomic variations in Pakistan to other parts of the world.

PATIENTS AND METHODS

We conducted a prospective study at Aga Khan University Hospital from December 2006 to December 2008. HBV genotype was determined in 257 HBV DNA-positive patients. Patients were divided into two groups according to HBeAg positivity. Mutations in the pre-core and core promoter regions of HBV were determined in HBeAg-negative patients by line probe INNOLIPA assay.

RESULTS

The mean±SD age of patients was 28±5 years; there were 201 (78%) men. HBeAg was positive in 219 (85%) patients and negative in 38 (15%). HBeAg-positive patients were younger than HBeAg-negative patients (95% vs 21% in ≤30 years, p<0.001). HBV genotype D found in 247 (96.2 %) patients followed by a combined infection with HBV genotype B+D in 9 (3.3%) and 1 (0.5%) with genotype A. The mutations identified in 38 HBeAg-negative patients were T1762/A1764 in 21 (55.2%), PC mutant in 7 (18.4%), T1762/A1764/PC mutant in 2 (5%) and T1762/A1764/PC wild mutation in 1 (2%); no mutation identified in 7 (18.4%). Phylogenetic analysis did not show any significant differences between HBV genotype D isolated from Pakistan and those isolated from other parts of the world.

CONCLUSIONS

HBV genotype D is predominant in Pakistan, irrespective of HBeAg status. PC and BCP mutations were found in significant numbers of patients infected with genotype D. The HBV genotype D isolates from Pakistan are identical to the sequences isolated from other parts of the world.

The clinical implications of hepatitis B virus genotype: Recent advances

Outcomes of chronic hepatitis B virus (HBV) infection are heterogeneous. Estimates of annual incidence of cirrhosis and hepatocellular carcinoma (HCC) are 2-10% and 1-3%, respectively. Several viral factors, including HBV genotype, viral load and specific viral mutations, have been associated with disease progression. Among these, HBV genotype is not only predictive of clinical outcomes but has also been associated with response to interferon treatment. Currently, at least 10 HBV genotypes and several subtypes have been identified; they have distinct geographic distribution. Acute infection with genotypes A and D results in higher rates of chronicity than genotypes B and C. Compared to genotype A and B cases, patients with genotypes C and D have lower rates of spontaneous hepatitis B e antigen (HBeAg) seroconversion; when this occurs, it tends to be delayed. HBV genotype C has a higher frequency of basal core promoter (BCP) A1762T/G1764A mutation, pre-S deletion and is associated with higher viral load than genotype B. Similarly, genotype D has a higher prevalence of BCP A1762T/G1764A mutation than genotype A. These observations suggest important pathogenic differences between HBV genotypes. These may contribute to more severe liver disease, including cirrhosis and HCC with genotypes C and D HBV infection. In addition, genotype A and B patients have better responses to interferon-based therapy than genotypes C and D, but there are few consistent differences for direct HBV antivirals. In conclusion, genotyping of chronic HBV infections can help practicing physicians identify those at risk of disease progression and determine optimal anti-viral therapy.

High frequency of lamivudine resistance mutations in Brazilian patients co-infected with HIV and hepatitis B

This study analyzed the genotype distribution and frequency of lamivudine (LAM) and tenofovir (TDF) resistance mutations in a group of patients co-infected with HIV and hepatitis B virus (HBV). A cross-sectional study of 847 patients with HIV was conducted. Patients provided blood samples for HBsAg detection. The load of HBV was determined using an "in-house" real-time polymerase chain reaction. HBV genotypes/subgenotypes, antiviral resistance, basal core promoter (BCP), and precore mutations were detected by DNA sequencing. Twenty-eight patients with co-infection were identified. The distribution of HBV genotypes among these patients was A (n = 9; 50%), D (n = 4; 22.2%), G (n = 3; 16.7%), and F (n = 2; 11.1%). Eighteen patients were treated with LAM and six patients were treated with LAM plus TDF. The length of exposure to LAM and TDF varied from 4 to 216 months. LAM resistance substitutions (rtL180M + rtM204V) were detected in 10 (50%) of the 20 patients with viremia. This pattern and an accompanying rtV173L mutation was found in four patients. Three patients with the triple polymerase substitution pattern (rtV173L + rtL180M + rtM204V) had associated changes in the envelope gene (sE164D + sI195M). Mutations in the BCP region (A1762T, G1764A) and in the precore region (G1896A, G1899A) were also found. No putative TDF resistance substitution was detected. The data suggest that prolonged LAM use is associated with the emergence of particular changes in the HBV genome, including substitutions that may elicit a vaccine escape phenotype. No putative TDF resistance change was detected after prolonged use of TDF.

Molecular analysis of HBV genotypes and subgenotypes in the Central-East region of Tunisia

Background

In Tunisia, country of intermediate endemicity for Hepatitis B virus (HBV) infection, most molecular studies on the virus have been carried out in the North of the country and little is known about other regions. The aim of this study was to determine HBV genotype and subgenotypes in Central-East Tunisia. A total of 217 HBs antigen positive patients were enrolled and determination of genotype was investigated in 130 patients with detectable HBV DNA. HBV genotyping methods were: PCR-RFLP on the pre-S region, a PCR using type-specific primers in the S region (TSP-PCR) and partial sequencing in the pre-S region.

Results

Three genotypes (D, B and A) were detected by the PCR-RFLP method and two (D and A) with the TSP-PCR method, the concordance between the two methods was 93%. Sequencing and phylogenetic analysis of 32 strains, retrieved the same genotype (D and A) for samples with concordant results and genotype D for samples with discordant results. The sequences of discordant genotypes had a restriction site in the pre-S gene which led to erroneous result by the PCR-RFLP method. Thus, prevalence of genotype D and A was 96% and 4%, respectively. Phylogenetic analysis showed the predominance of two subgenotypes D1 (55%) and D7 (41%). Only one strain clustered with D3 subgenotype (3%).

Conclusions

Predominance of subgenotype D7 appears to occur in northern regions of Africa with transition to subgenotype D1 in the East of the continent. HBV genetic variability may lead to wrong results in rapid genotyping methods and sequence analysis is needed to clarify atypical results.

Significant association of different preS mutations with hepatitis B-related cirrhosis or hepatocellular carcinoma

BACKGROUND

The associations of nucleotide substitution mutations in the preS region of hepatitis B virus (HBV) with hepatocellular carcinoma (HCC) and cirrhosis remain unknown. We aimed to determine the associations of preS mutations with HCC or cirrhosis.

METHODS

HBV from 603 asymptomatic hepatitis B surface antigen carriers (ASCs), 219 chronic hepatitis B (CHB) patients, 119 cirrhosis patients, and 231 HCC patients were genotyped and sequenced in the preS region. Nucleotides with the highest frequencies in HBV from the hepatitis B e antigen (HBeAg)-positive ASCs were treated as "wild-type" nucleotides. Twenty-one preS1 mutations and 14 preS2 mutations were evaluated. Multivariate regression analyses were applied to determine factors independently associated with cirrhosis or HCC.

RESULTS

Most (85.7%) preS2 mutations were associated with CHB compared with ASCs, whereas most preS1 mutations were associated with HCC compared with the cirrhosis patients or CHB patients. Compared with the CHB patients, 81.0% preS1 mutations in genotype C were inversely associated with cirrhosis. Multivariate regression analyses showed that C2964A, C3116T, and C7A were novel factors associated with HCC compared with those without HCC, whereas A2964C and T3116C were independently associated with cirrhosis compared with ASCs and the CHB patients. Combined preS1 mutations had specificities greater than 95%, while C3116T and C7A had moderate sensitivities and specificities, for HCC.

CONCLUSIONS

C2964A, C3116T, and C7A are novel markers independently associated with an increased risk of HCC, while A2964C and T3116C are novel markers independently associated with an increased risk of cirrhosis. Combined preS1 mutations are specific for HCC.

Hepatitis B virus: from diagnosis to treatment

During the next few decades, vaccination against hepatitis B virus (HBV) will dramatically change the epidemiological profile of this worldwide infection especially when Heath Policies encourage including HBV vaccination program for the newborns. However, it is still estimated that more than 2000millions living people have met HBV. Symptomatic hepatitis with jaundice is less frequent than asymptomatic infection; however, as much as 350millions of individuals remain chronically infected by HBV. In these cases, the need for efficient antiviral therapy remains clear when a viral replication is observed to control the risk of progression and the need for liver transplantation, which represents the only end-stage treatment. Indeed, patients having chronic hepatitis B (CHB) can now be successfully treated using nucleos(t)ide analogs (NA) or pegylated interferon (PEG-IFN). Therefore, beside vaccination, prevention of the progression of the disease to cirrhosis and liver decompensation, leading to end-stage liver disease and/or to hepatocellular carcinoma, by inhibiting viral replication seems to represent the best approach to improve survival. At last but not least, co-morbidities and other viral infections, leading also to chronic liver cirrhosis or liver inflammation such as the specific satellite delta virus (HDV), human immunodeficency virus (HIV) and/or hepatitis C (HCV) virus, are able to accelerate the progression and have to be taken in account. Interestingly, in treated infection, the dogma of the irreversibility of the liver fibrosis, when the cirrhosis is constituted, is tumbling down. In this review, we will focus on the clinical, virological and therapeutic aspects of hepatitis B infection in order to expose the proposals to follow-up and treat HBV-infected patients and the prevention of drug-resistant HBV mutants that frequently arise, leading to treatment failure and progression to liver disease.

HBV genotype C is independently associated with cirrhosis in community-based population

AIM: To determine the association of hepatitis B virus (HBV) genotypes with probable cirrhosis and fatty liver in community-based populations.

METHODS: A multi-stage cluster probability sampling method was applied to recruit 10 167 subjects aged between 6 and 72 years from our epidemiological bases in Eastern China. After excluding the subjects co-infected with hepatitis C or hepatitis D viruses, the hepatitis B surface antigen (HBsAg)-positive subjects were examined for HBV genotype, serum viral load, alanine aminotransferase (ALT), hepatitis B e antigen (HBeAg) status, and ultrasonographic changes. Logistic regression models were used to determine the factors associated with probable cirrhosis and fatty liver.

RESULTS: Of 634 HBsAg-positive subjects with HBV genotype determined, 82 had probable cirrhosis (ultrasonographic score ≥ 5), 42 had ultrasonographic fatty liver. Probable cirrhosis was only found in the HBeAg-negative subjects, and more frequently found in the subjects with genotype C than in those with genotype B (14.8% vs 8.0%, P = 0.018). In HBeAg-negative subjects, high viral load was frequently associated with abnormal ALT level, while ALT abnormality was more frequent in those with probable cirrhosis than those without (19.5% vs 7.8%, P = 0.001). Univariate analysis showed that age, sex, HBV genotypes, and viral load were not significantly associated with ultrasonographic fatty liver, whereas ALT abnormality was significantly related to ultrasonographic fatty liver (OR = 4.54, 95% CI: 2.11-9.75, P < 0.001). Multivariate analysis demonstrated that HBV genotype C, age (≥ 45 years), male sex, and ALT abnormality were independently associated with probable cirrhosis (AOR = 2.30, 95% CI: 1.26-4.19; AOR = 1.81, 95% CI: 1.10-2.99; AOR = 1.74, 95% CI: 1.03-2.95; AOR = 2.98, 95% CI: 1.48-5.99, respectively).

CONCLUSION: A crude prevalence of probable cirrhosis is 12.9% in the community-based HBV-infected subjects. HBV genotype C is independently associated with probable cirrhosis in the HBeAg-negative subjects.