Molecular epidemiological study of hepatitis B virus in Thailand based on the analysis of pre-S and S genes

Immune-Escape Mutations Are Prevalent among Patients with a Coexistence of HBsAg and Anti-HBs in a Tertiary Liver Center in the United States

The concurrent seropositivity of HBsAg and anti-HBs has been described among patients with chronic hepatitis B (CHB), but its prevalence is variable. HBV S-gene mutations can affect the antigenicity of HBsAg. Patients with mutations in the 'α' determinant region of the S gene can develop severe HBV reactivation under immunosuppression. In this study at a tertiary liver center in the United States, we evaluated the frequency and virological characteristics of the HBsAg mutations among CHB patients with the presence of both HBsAg and anti-HBs. In this cohort, 45 (2.1%) of 2178 patients were identified to have a coexistence of HBsAg and anti-HBs, and 24 had available sera for the genome analysis of the Pre-S1, Pre-S2, and S regions. The frequency of mutations in the S gene was significantly higher among those older than 50 years (mean 8.5 vs. 5.4 mutations per subject, p = 0.03). Twelve patients (50%) had mutations in the 'α' determinant region of the S gene. Mutations at amino acid position 126 were most common in eight subjects. Three had a mutation at position 133. Only one patient had a mutation at position 145-the classic vaccine-escape mutation. Despite the universal HBV vaccination program, the vaccine-escape mutant is rare in our cohort of predominantly Asian patients.

Hepatitis B virus genotypes associated with pregnant women in Northern Thailand

BACKGROUND

Mother-to-child transmission of hepatitis B virus (HBV) is the major route of transmission causing persistent infection. The prevalence of HBV infection and HBV genotypes found in different geographical areas varies from country to country. Therefore, this study was conducted to identify the HBV genotypes in HBV-infected pregnant women in Northern Thailand.

METHODS

Stored blood samples that were collected from 145 HBsAg-positive pregnant women who gave birth at Maharaj Nakorn Chiang Mai Hospital, Chiang Mai, Thailand from 2017 to 2020 were analyzed. The partial nucleotide sequence of the S gene of HBV was amplified by nested PCR and sequenced. All sequences were analyzed phylogenetically together with the reference strains to define the HBV genotypes.

RESULTS

A total of 31 blood samples from 145 HBsAg-positive pregnant women were positive for HBV by nested PCR. The detected HBV strains were identified as presumptive subgenotypes C1 (77.4%; 24/31), B9 (9.7%; 3/31), C2 (3.2%; 1/31), B2 (3.2%; 1/31), B4 (3.2%; 1/31), and presumptive B4/C2 recombinant subgenotype (3.2%; 1/31).

CONCLUSIONS

The findings revealed that presumptive subgenotype C1 was the most common subgenotype circulating in pregnant women in Northern Thailand and accounted for 77.4% of cases, followed by presumptive subgenotypes B9, C2, B2, and B4. Furthermore, this study reported, for the first time in Thailand, the HBV genotypes and presumptive subgenotypes, particularly subgenotype B9 circulating in pregnant women.

A Recent Prevalence of Hepatitis B Virus (HBV) Genotypes and Subtypes in Asia: A Systematic Review and Meta-Analysis

Background and Aim: Despite introducing the hepatitis B virus (HBV) vaccine, the incidence of the Hepatitis B virus globally is still a major health concern. This systematic review and meta-analysis were conducted to provide detailed information on the prevalence of HBV genotypes and subtypes in circulation in Asia. Methods: A systematic search for articles describing the prevalence of HBV genotypes and subtypes in Asia was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Results: Our search returned 207 eligible articles involving 49,279 genotypes and 7457 subtypes representing 28 Asian countries. A meta-analysis was performed on our eligible studies using the Random effect Model. The pooled prevalence of HBV genotypes showed that genotype C (30.9%) (95% CI, 27.5–34.5%; I2 = 97.57%; p < 0.001) was the most common HBV genotype in Asia, followed by genotype B (17.8%) (95% CI, 15.5–20.4%; I2 = 97.26%; p < 0.001) and genotype D (15.4%) (95% CI, 11.8–19.8%). Vietnam had the highest prevalence of genotype B, Lebanon had the highest prevalence of genotypes C, and Jordan had the highest prevalence of genotype D. There was variation in genotypic prevalence with respect to the target genes for HBV genotyping. Reverse dot blot hybridization had the highest estimate of genotypes B and C. HBV subtype C2 (40.0%) (95% CI, 33.3–47.0) is the most prevalent HBV subtype. Conclusion: Evidence from this study reveals that HBV genotypes C and B are the most dominant HBV genotypes in Asia, and HBV subtype C2 is more endemic in Asia.

Immune Tolerant Chronic Hepatitis B: The Unrecognized Risks

Chronic infection with hepatitis B virus (HBV) progresses through multiple phases, including immune tolerant, immune active, immune control, and, in a subset of patients who achieve immune control, reactivation. The first, the immune tolerant phase, is considered to be prolonged in duration but essentially benign in nature, lacking long-term consequences, and thus not recommended for antiviral therapy. This review challenges the notion that the immune tolerant phase is truly benign and considers the possibility that events during this phase may contribute significantly to cirrhosis, hepatocellular carcinoma (HCC), and the premature death of 25% of HBV carriers worldwide. Thus, earlier treatment than recommended by current guidelines should be considered. Low therapeutic coverage exacerbated by restrictive treatment guidelines may facilitate disease progression in many patients but also increase the risk of neonatal and horizontal transmission from untreated mothers to their children. While a prophylactic vaccine exists, there are many areas worldwide where the treatment of adults and the delivery of an effective vaccination course to newborns present difficult challenges.

Alanine aminotransferase course, serum hepatitis B virus DNA, and liver stiffness measurement for therapeutic decisions in hepatitis B e antigen-negative chronic hepatitis B

AIM

To evaluate the utility of the combination of alanine aminotransferase (ALT) course, hepatitis B virus (HBV) DNA level, and liver stiffness measurement (LSM) for determining significant liver disease in hepatitis B e antigen (HBeAg)-negative patients.

METHODS

Three hundred and ninety nine consecutive HBeAg-negative patients with HBV DNA >2000 IU/mL and documented serial measurements of ALT were enrolled to undergo LSM followed by liver biopsy.

RESULTS

Using ALT <40 IU/L as a normal value, 142 patients had persistently normal ALT (PNALT), whereas 257 had persistently or intermittently elevated ALT (PIEALT) in the prior year. Among patients with HBV DNA of 2000-19 999, 20 000-199 999, and ≥200 000 IU/mL, significant pathological lesions defined as the presence of moderate to severe necroinflammation and/or significant fibrosis by METAVIR scoring was present in 40%, 45%, and 71% of the PIEALT group, and 15%, 31%, and 36% of the PNALT group, respectively. In PNALT patients with HBV DNA <20 000 IU/mL, liver biopsy could be avoided in 88% when LSM <7 kPa is used as an indicator of non-significant liver histology but 12% of those who indeed had significant pathological lesions would be missed. In PIEALT patients with HBV DNA ≥20 000 IU/mL, the need for liver biopsy could be reduced by 53% with a false positive rate of 14% when LSM ≥7 kPa is used as a predictor of significant pathological lesions.

CONCLUSION

The combination of serial ALT, viral load, and LSM appears to be a promising non-invasive tool. A management algorithm for HBeAg-negative patients comprising these non-invasive measures is proposed with liver biopsy being pursued in selected cases.

Hepatitis B virus genotypes and genome characteristics in China

AIM: To analyze the hepatitis B virus (HBV) characters in China, as well as the correlation between several HBV mutation and hepatitis symptoms.

METHODS: A total of 1148 HBV genome sequences from patients throughout China were collected via the National Center For Biotechnology Information database (information including: genotype, territory and clinical status). HBV genotypes were classified by a direct reference from the Genbank sequence annotation, phylogenetic tree and online software analysis (http://www.ncbi.nlm.nih.gov/projects/genotyping/formpage.cgi). The phylogenetic tree was constructed based on the neighbor-joining method by MEGA5.0 software. HBV sequences were grouped based on phylogenetic tree and the distance between the groups was calculated by using the computer between group mean distance methods. Seven hundred and twelve HBV sequences with clear annotation of clinical symptoms were selected to analyses the correlation of mutation and clinical symptoms. Characteristics of sequences were analyzed by using DNAStar and BioEdit software packages. The codon usage bias and RNA secondary structures analysis were performed by RNAdraw software. Recombination analysis was performed by using Simplot software.

RESULTS: In China, HBV genotype C was the predominant in Northeastern, genotype B was predominant in Central Southern areas, genotype B and C were both dominant in Southwestern areas, and the recombinant genotype C/D was predominant in Northwestern areas. C2 and B2 were identified as the two major sub-genotypes, FJ386674 might be a putative sub-genotype as B10. The basal core promoter double mutation and pre-C mutation showed various significant differences between hepatitis symptoms. In addition to ATG, many other HBV initiation codons also exist. HBV has codon usage bias; the termination codon of X, C and P open reading frames (ORF) were TAA, TAG, and TGA, respectively. The major stop codons of S-ORF were TAA (96.45%) and TGA (83.60%) in B2 and C2 subtype, respectively.

CONCLUSION: This study recapitulated the epidemiology of HBV in China, and the information might be meaningful critical for the future prevention and therapy of HBV infections.

Distribution and epidemiologic trends of HBV genotypes and subtypes in 14 countries neighboring china

BACKGROUND

The number of cases of HBV infection reported by the WHO for each district and country is positively correlated with the number of HBV sequences in the database isolated from the corresponding district and country.

OBJECTIVES

This study determined distribution characteristics of HBV genotypes and subtypes in 14 countries neighboring China. The progress made in genomic research involving HBV was also reviewed.

MATERIALS AND METHODS

Nine hundred fifty-one complete genome sequences of HBV from 14 countries neighboring China were selected from NCBI. The sequence-related information was analyzed and recorded. One hundred seventy-two sequences of HBV genotype B were screened for alignment using DNA star and MEGA 5.1.

RESULTS

Dominant HBV genotypes in the countries neighboring China were genotypes B, C and D and dominant subtypes were adw2 and adrq+. The association between genotype and serotype of HBV in these countries was shown to differ from previous research results. As shown by sequence alignment, the sequence divergence between five subgenotypes (B3, B5, B7, B8 and B9) was below 4%. The B subgenotypes shared six common specific amino acid sites in the S region.

CONCLUSIONS

The B3, B5, B7, B8 and B9 subgenotypes can be clustered into quasi-sub-genotype B3 and the open reading frame of HBV has a start codon preference; however, whether a mutation in the start codon in the pre-S2 region has an impact on survival and replication of HBV remains to be determined.

Variations and mutations in the hepatitis B virus genome and their associations with clinical characteristics

Hepatitis B virus (HBV) infection is major global issue, because chronic HBV infection is strongly associated with liver cancer. HBV spread worldwide with various mutations and variations. This variability, called quasispecies, is derived from no proof-reading capacity of viral reverse transcriptase. So far, thousands of studies reported that the variety of genome is closely related to the geographic distribution and clinical characteristics. Recent technological advances including capillary sequencer and next generation sequencer have made in easier to analyze mutations. The variety of HBV genome is related to not only antigenicity of HBs-antigen but also resistance to antiviral therapies. Understanding of these variations is important for the development of diagnostic tools and the appropriate therapy for chronic hepatitis B. In this review, recent publications in relation to HBV mutations and variations are updated and summarized.

Hepatitis B Virus-Related Hepatocellular Carcinoma: Pathogenic Mechanisms and Novel Therapeutic Interventions

BACKGROUND

Infection with the hepatitis B virus (HBV) is one of most important risk factors for hepatocellular carcinoma (HCC). Indeed, HBV is considered a group 1 human carcinogen and is a highly oncogenic agent. HBV cannot be effectively controlled or completely eliminated, so chronic HBV infection is a public health challenge worldwide.

SUMMARY

It is now believed that HBV-induced HCC involves a complex interaction between multiple viral and host factors. Many factors contribute to HBV-associated HCC, including products of HBV, viral integration and mutation, and host susceptibility. This review outlines the main pathogenic mechanisms with a focus on those that suggest novel targets for the prevention and treatment of HCC.

KEY MESSAGE

HBV infection is an important risk factor for HCC. Understanding the interaction between viral and host factors in HBV-induced HCC will reveal potential targets for future therapies.

PRACTICAL IMPLICATIONS

The two main therapeutic strategies consist of antiviral agents and immunotherapy-based approaches. Dendritic cell-based immunotherapy is promising for restoring the T cell-mediated antiviral immune response. Another approach is the specific expansion of the host's pool of HBV-specific T cells. Stimulation of the Toll-like receptors (TLRs), particularly TLR9, provides another means of boosting the antiviral response. Combination therapy with cytokines (interferon gamma and tumor necrosis factor alpha) plus lamivudine is more effective than these agents used alone. Therapeutic vaccines are being developed as an alternative to long-term antiviral treatment or as an adjunct.

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.

The N-Glycosylation Modification of LHBs (Large Surface Proteins of HBV) Effects on Endoplasmic Reticulum Stress, Cell Proliferation and its Secretion

BACKGROUND

The mutations of LHBs in pre-S, especially in pre-S2, are definitive in hepatocellular carcinoma (HCC) associated with HBV. However, the mechanisms of the N-glycosylation modification in LHBs are unclear. The N-glycosylation modification of LHBs affects Endoplasmic Reticulum stress, cell proliferation and its secretion which was further studied.

OBJECTIVES

The objectives of our studies was to indentified that modification of LHBs by N glycosylation modulate their secretion, affect ER stress or expression of cycling, cell cycle and proliferation.

MATERIALS AND METHODS

The LHBs was mutated; then expression of proteins related to endoplasmic reticulum stress and EAED path of L02 cells affected by LHBs and its mutations was evaluated. LHBs proteins bound to multiubiquitin chains and its glycosylation motif were studied. The subcellular localization and secretion of LHBs and its mutations were identified. The effect on cell cycle and proliferation by LHBs and its mutations were detected.

RESULTS

These data demonstrated that the N-glycosylation motifs of LHBs were associated with ER stress. The N15S, N123S, and N177S mutated LHBs proteins could induce overexpression of EDEM in L02 cells. LHBs and its mutated proteins contained p62-derived UBA domain, which could affect expression of cyclins. The subcellular localization of LHBs in endoplasmic reticulum was similar to its mutations. The secretion of LHBs was blocked by N320K mutation, which could induce an increase in G1 phase and inhibition of S phase, and inhibited mitotic entry.

CONCLUSIONS

In conclusion, our studies powerfully demonstrated that modification of LHBs by N glycosylation could modulate their secretion, affect ER stress or expression of cycling, cell cycle and proliferation. The N320K may be the key sites N-linked glycosylation modification of LHBs. It may be a mechanism of HBV-induced HCC.

Association between HBX status, aflatoxin-induced R249S TP53 mutation and risk of hepatocellular carcinoma in a case-control study from Thailand

Hepatocellular carcinoma (HCC) is associated with hepatitis B virus (HBV) chronicity and dietary exposure to aflatoxin, a mutagen targeting codon 249 of tumor suppressor TP53 (R249S mutation). Based on a case-control in Thailand, we have measured R249S and the status of HBX gene in plasma DNA of 176 cases and 133 referents. Detection of HBX complete sequences was associated with R249S in HCC with no documented prior cirrhosis but not in HCC developing in a context of cirrhosis or in non-cancer chronic liver diseases. Thus, R249S may specifically cooperate with HBX in a pathway to HCC that bypasses cirrhosis.

Hepatitis B virus pre-S2 start codon mutations in Indonesian liver disease patients

AIM: To identify the prevalence of pre-S2 start codon mutations and to assess their association with liver disease progression.

METHODS: The mutations were identified by direct sequencing from 73 asymptomatic carriers, 66 chronic hepatitis (CH), 66 liver cirrhosis (LC) and 63 hepatocellular carcinoma (HCC) patients. Statistical significances were determined using Fisher’s exact test, χ² test, and t-test analyses whenever appropriate. Pre-S mutation as a risk factor for advanced liver disease was estimated by unconditional logistic regression model adjusted with age, sex, and hepatitis B e antigen (HBeAg). P < 0.05 was considered significant.

RESULTS: Mutation of the hepatitis B virus (HBV) pre-S2 start codon was found in 59 samples from 268 subjects (22.0%), with higher prevalence in patients with cirrhosis 27/66 (40.9%) followed by HCC 18/63 (28.6%), chronic hepatitis 12/66 (18.2%) and asymptomatic carriers 2/73 (2.7%) (P < 0.001). Logistic regression analysis showed that pre-S2 start codon mutation was an independent factor for progressive liver disease. Other mutations, at T130, Q132, and A138, were also associated with LC and HCC, although this was not statistically significant when adjusted for age, sex, and HBeAg. The prevalence of pre-S2 start codon mutation was higher in HBV/B than in HBV/C (23.0% vs 19.1%), whilst the prevalence of T130, Q132, and A138 mutation was higher in HBV/C than in HBV/B. The prevalence of pre-S2 start codon mutation was higher in LC (38.9%) and HCC (40.0%) than CH (5.6%) in HBeAg(+) group, but it was similar between CH, LC and HCC in HBeAg(-) group.

CONCLUSION: Pre-S2 start codon mutation was higher in Indonesian patients compared to other Asian countries, and its prevalence was associated with advanced liver disease, particularly in HBeAg(+) patients.

Nucleos(t)ide analogues treatment outcome in genotype B and C chronic hepatitis B

Background:

Hepatitis B genotypes influence the course and severity of the disease.

Aim:

To compare the treatment outcome of chronic hepatitis B genotype B and C patients after treating with nucleos(t)ide analogues for six months.

Patients and Methods:

Forty chronic hepatitis B patients attending the liver clinic of Hospital for Tropical diseases, Bangkok, were studied in retrospective cohort design. Six genotype B patients (15%) and thirty-four genotype C patients (85%) were treated. Serum hepatitis B viral load, serum alanine amino transferase level, HBeAg status and alpha-feto protein level were measured at the time of starting nucleos(t) analogues therapy, and six months later. Besides, achievement of undetectable viral load was assessed in patients with normal serum alanine amino transferase compared to patients with high serum alanine amino transferase level.

Results:

After six months of nucleos (t) analogues treatment, achievement of undetectable hepatitis B viral load was higher in genotype B patients (66.7%) than in genotype C patients (42.4%) (Relative Risk=1.57, 0.79-3.14). Biochemical remission, HBeAg seroconversion and tumor marker levels between the two groups were not significantly different. Moreover, achievement of undetectable hepatitis B viral load was significantly higher in normal alanine amino transferase level (75%) than in patients with high serum alanine amino transferase level (33.3%) on nucleos(t)ide analogue treatment (Relative Risk=2.25, 1.20- 4.20).

Conclusion:

Chronic hepatitis B treatment outcome between genotype B and C were not significantly different. Patients with normalized serum alanine amino transferase level tend to achieve undetectable viral load after nucleoside analogues treatment.

Challenges in Providing Treatment and Care for Viral Hepatitis among Individuals Co-Infected with HIV in Resource-Limited Settings

Hepatitis B and C infections are prevalent among HIV-infected individuals with different epidemiologic profiles, modes of transmission, natural histories, and treatments. Southeast Asian countries are classified as "highly prevalent zones," with a rate of hepatitis B and C coinfection in people living with HIV/AIDS of approximately 3.2-11%. Majority of hepatitis B coinfection is of genotype C. Most of the patients infected with hepatitis C in Thailand have genotype 3 which is significantly related to intravenous drug use whereas, in Vietnam, it is genotype 6. The options for antiretroviral drugs are limited and rely on global funds and research facilities. Only HBV treatment is available for free through the national health scheme. Screening tests for HBV and HCV prior to commencing antiretroviral treatment are low. Insufficient concern on hepatitis-virus-related liver malignancy and long-term hepatic morbidities is noted. Cost-effective HCV treatment can be incorporated into the national health program for those who need it by utilizing data obtained from clinical research studies. For example, patients infected with HCV genotype 2/3 with a certain IL-28B polymorphism can be treated with a shorter course of interferon and ribavirin which can also help reduce costs.

Low prevalence of hepatitis B virus pre-S deletion mutation in Indonesia

The molecular epidemiological study of hepatitis B virus (HBV) in Indonesia is still limited. This study was aimed to identify the prevalence of HBV pre-S deletion/insertion mutations, and to assess the association of pre-S deletion mutation with liver disease progression in Indonesia. Pre-S mutations were identified by direct sequencing. Of the 265 subjects, 32 samples (12.1%) harbored pre-S deletion/insertion mutations. The prevalence of those pre-S mutations was 2.7% (2/75), 12.9% (8/62), 16.7% (11/66), and 17.7% (11/62) in asymptomatic carrier, chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma groups, respectively. Statistical analysis showed significant difference among them (P = 0.024). In HBV genotype B (HBV/B), pre-S1, pre-S1/S2, and pre-S2 deletion mutations were detected respectively in 3 (17.6%), 4 (23.5%), and 9 (52.9%) of 17 samples. On the other hand, in HBV/C, 12 of 15 samples (80.0%) showed a pre-S2 deletion mutation, and only 2 samples (13.3%) demonstrated a pre-S1/S2 deletion mutation. These results suggest that in HBV/B deletion mutation tends to occur in pre-S1 or pre-S1/S2 region, while in HBV/C the deletion mutation usually occurs in the pre-S2 region. Analysis of complete genome of four viruses confirmed that 3 isolates were classified into HBV/B3, and 1 isolate was HBV/C1. However, SimPlot and BootScan analyses showed that isolate 08.10.002 was an intragenotypic recombinant between HBV/B3 and HBV/B4. As conclusion, the prevalence of HBV pre-S mutations was relatively low in Indonesian patients compared to those from Taiwan, Japan, and other Asian countries. There was a weak association between pre-S deletion mutation and progressive liver disease.

Coexistence of hepatitis B surface antigen and anti-HBs in Chinese chronic hepatitis B virus patients relating to genotype C and mutations in the S and P gene reverse transcriptase region

We aimed to determine the prevalence of the coexistence of HBsAg and anti-HBs and to analyze the clinical and virological features of infection, including amino acid (aa) patterns of the S gene and reverse transcriptase (RT) region in Chinese chronic hepatitis B (CHB) patients. Fifty-four (2.90%) CHB patients who were positive for both HBsAg and anti-HBs were tested, and sequences were obtained from 52 of them as well as 48 patients from a control group. S gene and RT region sequences were amplified and sequenced using in-house protocols. There was no significant difference between patients with and without anti-HBs with regard to age, gender, alanine aminotransferase level, and the proportion positive for HBeAg and HBcAb. The occurrence of genotype C (P = 0.001) and anti-HBeAb positivity (P = 0.027) was significantly higher in HBsAg+/anti-HBs+ individuals. In the S gene, the number of mutated residues in the HBsAg+/anti-HBs+ group was markedly higher than in control patients (1.88 versus 1.02 substitutions per 100 amino acids, P = 0.022). The amino acid exchange occurred mostly within the N-terminal region (2.15 versus 0.87 substitutions per 100 amino acids, P = 0.023) and the "a" determinant (3.61 versus 1.56 substitutions per 100 amino acids, P = 0.049) in the two groups. In the RT region, the mean number of substitution per 100 aa showed a tendency to be significantly higher in HBsAg+/anti-HBs+ patients than in controls (2.34 versus 1.46, P = 0.040). This study showed a prevalence of coexistence of anti-HBs in HBsAg-positive patients and an increased frequency of genotype C and aa variability within both HBsAg and RT involving functionally important regions of those proteins.

Molecular epidemiological study of hepatitis B virus among migrant workers from Cambodia, Laos, and Myanmar to Thailand

Although hepatitis B virus (HBV) infection is endemic in Southeast Asia, molecular epidemiological data on HBV circulating in some countries are limited. The aims of this study were to evaluate the seroprevalence of HBV and its genetic variability among migrant workers from Cambodia, Laos, and Myanmar in Thailand. Sera collected from 1,119 Cambodian, 787 Laotian, and 1,103 Myanmarese workers were tested for HBsAg. HBV DNA was amplified and the pre-S/S region was sequenced for genotyping and genetic mutation analysis. HBsAg was detected in 282 (9.4%). The prevalence of HBsAg among migrant workers from Cambodia, Laos, and Myanmar was 10.8%, 6.9%, and 9.7%, respectively. Of 224 subjects positive for HBV DNA, 86% were classified as genotype C (99% were sub-genotype C1) and 11.6% were genotype B (30.8%, 34.6%, and 30.8% were sub-genotypes B2, B3, and B4, respectively). Various point mutations in the "a" determinant region were detected in approximately 18% of these samples, of which Ile126Ser/Asn was the most frequent variant. Sequencing analysis showed that 19.1% of samples had pre-S mutations, with pre-S2 deletion as the most common mutant (7.7%) followed by pre-S2 start codon mutation (3.8%) and both pre-S2 deletion and start codon mutation (3.3%). High prevalence of HBV infection (approximately 7-11%) was found among migrant workers from Cambodia, Laos, and Myanmar, which may reflect the current seroprevalence in their respective countries. The data also demonstrated that HBV sub-genotype C1 was the predominant strain and various mutations of HBV occurring naturally were not uncommon among these populations.

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.

PreS deletion mutations of hepatitis B virus in chronically infected patients with simultaneous seropositivity for hepatitis-B surface antigen and anti-HBS antibodies

Hepatitis B surface antigen (HBsAg) and anti-HBs antibodies (anti-HBs) may coexist in certain chronic hepatitis B (CHB) patients. This study was designed to further explore the relationship between this coexistence and hepatitis B Virus (HBV) preS deletions. Sera of 28 patients carrying both HBsAg and anti-HBs (Group I) and those of another 28 HBsAg positive but anti-HBs negative patients (Group II) were collected from CHB patients. Direct sequencing of polymerase chain reaction products or sequencing of clones was applied to both groups to determine sequences of HBV preS and S genes. Genotyping of the S gene indicated that all sampled HBVs were either Genosubtype Ba or Genosubtype Ce. Seven samples in Group I harbored HBV preS deletion mutations. Three of the seven samples showed large deletion mutations in 3' terminus of preS1 and co-existence of the mutant type and the full-length wild type, and the remaining four samples showed deletion mutations in 5' terminus of preS2. All mutant strains were found to be genosubtype Ce. Only two samples in Group I showed G145R/A mutation. Only one sample in Group II contained preS deletion mutation. It is therefore concluded that HBV preS deletion mutations are likely to be related to the coexistence of HBsAg and anti-HBs in CHB patients (P-value = 0.024). Some immune reactions may select for the preS deletion in CHB patients with anti-HBs, the possible marker for immune selection.

A pre-S gene chip to detect pre-S deletions in hepatitis B virus large surface antigen as a predictive marker for hepatoma risk in chronic hepatitis B virus carriers

BACKGROUND

Chronic hepatitis B virus (HBV) infection is an important cause of hepatocellular carcinoma (HCC) worldwide. The pre-S1 and -S2 mutant large HBV surface antigen (LHBS), in which the pre-S1 and -S2 regions of the LHBS gene are partially deleted, are highly associated with HBV-related HCC.

METHODS

The pre-S region of the LHBS gene in two hundred and one HBV-positive serum samples was PCR-amplified and sequenced. A pre-S oligonucleotide gene chip was developed to efficiently detect pre-S deletions in chronic HBV carriers. Twenty serum samples from chronic HBV carriers were analyzed using the chip.

RESULTS

The pre-S deletion rates were relatively low (7%) in the sera of patients with acute HBV infection. They gradually increased in periods of persistent HBV infection: pre-S mutation rates were 37% in chronic HBV carriers, and as high as 60% in HCC patients. The Pre-S Gene Chip offers a highly sensitive and specific method for pre-S deletion detection and is less expensive and more efficient (turnaround time 3 days) than DNA sequencing analysis.

CONCLUSION

The pre-S1/2 mutants may emerge during the long-term persistence of the HBV genome in carriers and facilitate HCC development. Combined detection of pre-S mutations, other markers of HBV replication, and viral titers, offers a reliable predictive method for HCC risks in chronic HBV carriers.

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.