Emergence of vaccine-induced escape mutant of hepatitis B virus with multiple surface gene mutations in a Korean child

Association of Coexistent Hepatitis B Surface Antigen and Antibody With Severe Liver Fibrosis and Cirrhosis in Treatment-Naive Patients With Chronic Hepatitis B

IMPORTANCE

Coexistence of hepatitis B surface antigen (HBsAg) and antibody against HBsAg (anti-HBs) constitutes an atypical serological profile in chronic hepatitis B virus infection, and the association between coexistent HBsAg and anti-HBs with severe liver fibrosis and cirrhosis in patients with chronic hepatitis B (CHB) remains unclear.

OBJECTIVE

To investigate the association of coexistent HBsAg and anti-HBs with severe liver fibrosis and cirrhosis in patients with CHB.

DESIGN, SETTING, AND PARTICIPANTS

Consecutive treatment-naive patients with CHB from 2 medical institutions in China were enrolled between January 10, 2015, and March 31, 2021. Severe liver fibrosis and cirrhosis were identified using the aspartate transaminase (AST) to platelet ratio index (APRI), the fibrosis index based on 4 factors (FIB-4; factors comprise age, AST level, alanine aminotransferase [ALT] level, and platelet count), transient elastography, or ultrasonography. Data were analyzed from August 1, 2021, to April 15, 2022.

MAIN OUTCOMES AND MEASURES

The primary outcomes were rates of severe liver fibrosis and cirrhosis among patients with vs patients without coexistant HBsAg and anti-HBs. Severe liver fibrosis was defined as an APRI score of 1.5 or higher, a FIB-4 score of 3.25 or higher, or a liver stiffness measurement of 8 kPa or higher; cirrhosis was defined as an APRI score of 2.0 or higher, a FIB-4 score of 6.5 or higher, a liver stiffness measurement of 11 kPa or higher, or ultrasonographic findings suggestive of cirrhosis.

RESULTS

Of 6534 enrolled patients, 4033 patients (61.7%) were male, and the median (IQR) age was 41.0 (33.0-52.0) years. A total of 277 patients (4.2%) had coexistent HBsAg and anti-HBs. Patients with vs without anti-HBs were older (median [IQR], 46.0 [33.0-55.5] years vs 41.0 [33.0-52.0] years) and had a higher proportion of hepatitis B e antigen (HBeAg) positivity (123 of 277 patients [44.4%] vs 2115 of 6257 patients [33.8%]; P < .001), higher ALT levels (median [IQR], 45.1 [24.6-119.0] U/L vs 36.7 [22.0-77.0] U/L; P = .001) and AST levels (median [IQR], 35.0 [23.5-68.4] U/L vs 28.3 [21.6-51.0] U/L; P < .001), and lower platelet counts (median [IQR], 173.0 × 103/μL [129.0-212.5 × 103/μL] vs 185.0 × 103/μL [141.0-224.0 × 103/μL]; P = .004), albumin levels (median [IQR], 4.37 [4.11-4.56] g/dL vs 4.43 [4.17-4.61] g/dL; P = .02), and HBsAg levels (median [IQR], 2.8 log10 [1.6-3.4 log10] IU/mL vs 3.3 log10 [2.6-3.9 log10] IU/mL; P < .001). Compared with patients without anti-HBs, those with anti-HBs had higher APRI scores (median [IQR], 0.5 [0.3-1.4] vs 0.4 [0.3-0.9]; P < .001), FIB-4 scores (median [IQR], 1.4 [0.9-2.6] vs 1.1 [0.7-2.1]; P < .001), and liver stiffness values (median [IQR], 7.5 [6.2-9.8] kPa vs 6.3 [5.2-8.1] kPa; P = .003). Patients with anti-HBs also had higher proportions of severe liver fibrosis (102 of 277 patients [36.8%] vs 1397 of 6207 patients [22.5%]; P < .001) and cirrhosis (87 of 277 patients [31.4%] vs 1194 of 6213 patients [19.2%]; P < .001) compared with patients without anti-HBs. The coexistence of HBsAg and anti-HBs was independently associated with severe liver fibrosis (odds ratio [OR], 2.29; 95% CI, 1.56-3.38; P < .001) and cirrhosis (OR, 1.73; 95% CI, 1.12-2.68; P = .01) in the multivariate analysis. However, the association of coexistent HBsAg and anti-HBs with cirrhosis was only observed in patients with HBeAg negativity (OR, 1.66; 95% CI, 1.05-2.62; P = .03) and not in patients with HBeAg positivity (OR, 1.45; 95% CI, 0.87-2.43; P = .16).

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, the coexistence of HBsAg and anti-HBs was unusual in hepatitis B virus infection and was associated with more advanced liver diseases, such as severe liver fibrosis and cirrhosis, especially among patients with HBeAg negativity. These results suggest that close monitoring for liver fibrosis and cirrhosis is warranted in patients with CHB who have this serological profile.

Analysis of HBsAg mutations in the 25 years after the implementation of the hepatitis B vaccination plan in China

Since 1992, China has promoted hepatitis B vaccination. Concurrently, during this period, increasing use of immunoglobulins and nucleoside analogues might have exerted selective pressure on the hepatitis B virus (HBV) S gene, driving mutations in the HBsAg and changed the subtype. Using the National Center for Biotechnology Information database, we obtained gene sequence information for HBV strains from China and analysed changes in HBsAg subtypes and substitution mutations in HBsAg in 5-year intervals over 25 years to identify potential challenges to the prevention and treatment of hepatitis B. Most HBV sequences from China were genotype C (1996/2833, 70.46%) or B (706/2833, 24.92%). During the implementation of hepatitis B vaccination (recombinant hepatitis B vaccine was subgenotype A2 and HBsAg subtype adw2), the proportion of subtypes ayw1 and adw3 in genotype B and ayw2 in genotype C increased over the programme period. The overall mutation rate in HBsAg tended to decrease for genotype B, whereas, for genotype C, the rate increased gradually and then decreased slightly. Moreover, the mutation rate at some HBsAg amino acid sites (such as sG145 of genotype B and sG130 and sK141 of genotype C) is gradually increasing. HBV strains with internal stop codons of HBsAg (e.g., sC69*) and additional N-glycosylation (e.g., sG130N) mutations should be studied extensively to prevent them from becoming dominant circulating strains. The development of HBV vaccines and antiviral immunoglobulins and use of antiviral drugs may require making corresponding changes.

No evidence of occult HBV infection in population born after mass vaccination

Despite access to efficient hepatitis B virus (HBV) vaccine and universal immunization schedules, HBV infection remains a global health concern. HBV infection has decreased by this program. Nevertheless, breakthrough infections occur due to generation of occult HBV infection (OBI) and surface gene mutants in the immunized population. We aimed to determine the presence of OBI in a population born after initiation of nationwide HBV vaccination in Tehran, Iran. A HBV mass vaccination schedule was launched in Iran in 1993. For this study, we enrolled 1120 cases younger than 24 years. ELISA was applied to evaluate the presence of HBsAg, anti-HBs and anti-HBc. HBV-DNA presence was determined in all HBsAg-negative cases using nested polymerase chain reaction. The prevalence of HBsAg, anti-HBc and anti-HBs was 0.1, 0.54 and 39.9% respectively. Out of 6 anti-HBc-positive individuals, 4 cases also had anti-HBs. One case revealed HBsAg co-existence and the other one showed isolated anti-HBc. HBV-DNA was not detected in HBsAg-negative specimens. A very low prevalence of HBsAg and isolated anti-HBc was observed and no occult HBV infection was detected. It seems that evasion mutants are not a potential threat for HBV universal immunization efficacy in the vaccinated population.

Conformational analysis of hepatitis B virus surface antigen mutations among HIV-positive patients diagnosed with occult hepatitis B virus

Aim: We analyzed the role of mutations on the conformational structure of hepatitis B surface antigen (HBsAg) among HIV-1 positive patients who were infected with occult hepatitis B. Methods: The effects of the potential impact of amino-acid substitutions on the 3D structures of the HBsAg and molecular ducking were investigated using bioinformatics software. Results: Mutations classified in seven groups in accordance with their positions in occult hepatitis B virus infection patients. Some substitutions of residues could linearize the ‘a’ determinant loops. The affinity of binding in mutant HBsAg structures to MAb 12 was lower compared with the wild ones. T123I and P127L substitutions were undergone decrease in HBsAg antigenicity. Conclusion: These findings could be beneficial for a better understanding of hepatitis B virus antigen/antibody interactions.

Nearly half of Ultrio plus NAT non-discriminated reactive blood donors were identified as occult HBV infection in South China

Background

Blood donor plasma samples were detected by the Ultrio Plus NAT system for HBV, HCV and HIV-1 in Shenzhen blood center, China. Reactive samples underwent further discriminatory testing of a single virus by the same methodology. A large number of cases of non-discriminated reactive (NDR) donors were found, leaving potential risk of transmitting HBV if not deferrals. This study identified those non-discriminated samples.

Methods

The NDR plasma samples from blood donation screening were detected and classified by additional molecular and serological tests. Molecular characterizations of DNA+ NDR were determined by sequencing analysis.

Results

A number of 259 (0.21%) NDR plasma samples from screening of 123,280 eligible blood donors were detected, which presented a higher rate (91.1%) of anti-HBc reactivity and nearly half (46.7%) of HBV DNA+ that classified as occult HBV infection (OBI). Most OBI strains were wild-type HBV, but some substitutions V168A, S174 N, V177A, Q129R/L/H, G145A/R in S region of genotype B (OBI_B) and T47K/V/A, P49H/L, Q101R/H/K, S174 N, L175S, V177A, T118 M/R/K, G145R/A/K/E, R160K/N in S region of genotype C (OBI_C) strains were identified in high frequency.

Conclusion

Nearly half of NDR blood samples were identified as OBI, in which a number of important mutations were detected. NDR donation might have potential risk for HBV transmission, but need to be further investigated.

Current progress in the prevention of mother-to-child transmission of hepatitis B and resulting clinical and programmatic implications

There is currently no cure for hepatitis B chronic infections. Because new hepatitis B infections result mainly from perinatal transmission, preventing mother-to-child transmission is essential to reach by 2030 the goal of hepatitis B elimination set by the World Health Organization. The universal administration of hepatitis B vaccine to all infants, regardless of maternal status, starting with the birth dose, is the cornerstone of the strategy for elimination. Additional interventions, such as hepatitis B immune globulin administered to newborns and antiviral prophylaxis administered to hepatitis B infected pregnant women, may contribute to reaching the goal earlier. Hepatitis B immune globulin may remain out for reach of many pregnant women in low- and middle-income countries due to cost and logistic issues, but antivirals are cheap and do not require a cold chain for distribution. However, it has been observed that some viruses harbor mutations associated with escape from vaccine-elicited antibodies following immunization or administration of hepatitis B immune globulin. Also, resistance associated mutations have been described for several drugs used for treatment of hepatitis B infected patients as well as for the prevention of mother-to-child transmission. Whether these mutations have the potential to compromise the prevention of mother-to-child transmission or future treatment of the mother is a question of importance. We propose a review of important recent studies assessing tenofovir disoproxil fumarate for the prevention of mother-to-child transmission, and provides detailed information on the mutations possibly relevant in this setting.

Genetic variability in coding regions of the surface antigen and reverse transcriptase domain of hepatitis B virus polymerase, Colombia, 2002-2014

Introduction: Despite the availability of an effective vaccine and treatment to reduce the viral load and progressive hepatocellular injury, approximately 240 million people worldwide are chronically infected with the hepatitis B virus (HBV). In Colombia, the circulation of different viral genotypes has been confirmed. Mutations in the genome have been associated to antiviral therapy resistance, viral escape to neutralizing antibodies, occult infection and progression to hepatocellular carcinoma. Objective: To identify the genotypes and the presence of mutations in the coding region of the surface (S) antigen and the reverse transcriptase (RT) domain of the polymerase of HBV obtained from serum samples for hepatitis B diagnosis received by the Instituto Nacional de Salud during the period 2002-2014. Materials and methods: A total of 495 serum samples with previous HBsAg reactive result were used for molecular detection. A fragment of 1,591 nucleotides was sequenced, and the corresponding phylogenetic analysis was performed. Results: We detected the viral genome of HBV in 66 samples and 28 were successfully sequenced. The phylogenetic analysis allowed the identification of subgenotypes F3 and A2. The L180M and M204V resistance mutations were simultaneously identified in one sample, while the I169L resistance mutation was identified in another one. A single escape mutation, P120Q, was identified in one more. Two samples showed a deletion of 105 nucleotides in the preS1-preS2 region. Conclusions: The circulation of genotypes/subgenotypes F3 and A2 of HBV in Colombia was corroborated, as well as the presence of some resistance and escape mutations. The present study constitutes a contribution to the molecular epidemiology of HBV in Colombia.

Characterization of the "a" determinant region of the hepatitis B virus genome in Iranian patients at different clinical phases of chronic infection

AIM

To determine the distribution of important mutations of the "a" determinant region in the HBV genome among patients in different clinical phases of HBV infection.

BACKGROUND

Variations in Hepatitis B infection not only change the outcome of the disease but also the symptoms from which the chronic HBV patients are suffering.

METHODS

We have meticulously selected a total of 40 chronic HBV patients from four different subclasses of chronic HBV clinical phases including immune tolerant (IT), immune active (IA), inactive carrier (IC) and hepatitis B e antigen (HBeAg)-negative (ENEG); 10 samples per each phase. Mutations of the "a" determinant region were identified using PCR-Direct sequencing method.

RESULTS

17 amino-acid substitutions at 12 positions inside the "a" determinant were identified in all forty samples; 3 mutations in the IT group, 6 mutations in the IA phase, 3 mutations in the IC patients and 5 mutations in the ENEG phase. Different substitutions were observed in all four clinical phases. The IA phase was the most variant group with the highest number of amino-acid substitutions.

CONCLUSION

These results did not reveal a strong pattern to distinguish different clinical phases of Chronic HBV infection, but there are some obvious differences regarding the number and position of mutations between these four clinical phases.

Detection and molecular characterisation of a diagnosis escape variant associated with occult hepatitis B virus in Brazil

BACKGROUND

Many studies have identified mutations in the hepatitis B surface antigen (HBsAg) as important factors limiting the ability of commercial serological assays to detect this viral antigen. However, an association between mutations in the HBsAg gene and the occurrence of occult HBV infection (OBI) in patients has not been established.

OBJECTIVES

To detect hepatitis B virus (HBV) DNA in patients with anti-HBc as a unique serological marker, a previously published, cost-effective TaqMan-based real-time polymerase chain reaction (PCR) test with minor groove binding probes was adapted for use in this study. The current study also aimed to investigate HBsAg mutations and genotypes of HBV in OBI at the Viral Hepatitis Ambulatory Clinic in Rio de Janeiro to determine any possible association.

METHODS

Intra-assay and inter-assay reproducibility were determined, and the mean coefficient of variation values obtained were 2.07 and 3.5, respectively. Probit analysis indicated that the 95% detection level was 25 IU/mL. The prevalence of OBI was investigated in 35 serum samples with an ‘anti-HBc alone’ profile from individuals who attended our clinic between 2011 and 2013.

FINDINGS

HBV DNA was detected in only one sample, resulting in an OBI rate of 2.9%. Nucleotide sequencing of the pre-S/S region was performed to genotype and analyse mutations within the HBsAg gene of this HBV DNA. The HBV in the OBI case was classified as sub-genotype A1, and a sequence analysis of the small S gene revealed 12 mutations in the major hydrophilic region compared to the consensus A1 sequence. Most of these mutations occurred in amino acid residues that have been reported as clinically relevant because they have been implicated in vaccine escape and/or inability to detect HBsAg by commercial serological assays.

MAIN CONCLUSIONS

Our study suggests the importance of specific HBsAg mutations, different from those in D, B, and C genotypes, in sub-genotype A1 HBV associated with OBI.

HBV genotypes and drug resistance mutations in antiretroviral treatment-naive and treatment-experienced HBV-HIV-coinfected patients

BACKGROUND

The presence of HBV resistance mutations upon initiation or during antiretroviral therapy (ART) in HIV-coinfected patients is an important determinant of treatment response. The main objective of the study was to determine the prevalence of HBV resistance mutations in antiretroviral treatment-naive and treatment-experienced HBV-HIV-coinfected Ghanaian patients with detectable HBV viraemia.

METHODS

HBV-HIV-coinfected patients who were ART-naive or had received at least 9 months of lamivudine (3TC)-containing ART were enrolled in a cross-sectional study. Demographic and clinical data were collected and HBV DNA quantified. Partial HBV sequences were amplified by PCR and sequenced bi-directionally to obtain a 2.1-2.2 kb fragment for phylogenetic analysis of HBV genotypes and evaluation of drug resistance mutations.

RESULTS

Of the 100 HBV-HIV-coinfected study patients, 75 were successfully PCR-amplified, and 63 were successfully sequenced. Of these 63 patients, 27 (42.9%) were ART-experienced and 58 (92.1%) had HBV genotype E. No resistance mutations were observed in the 36 ART-naive patients, while 21 (77.8%) of 27 treatment-experienced patients had resistance mutations. All patients with resistance mutations had no tenofovir in their regimens, and 80% of them had HIV RNA <40 copies/ml. The 3TC resistance mutations rtL180M and rtM204V were observed in 10 (47.6%) of the 21 patients, while 5 patients (23.8%) had rtV173L, rtL180M and rtM204V mutations.

CONCLUSIONS

A high proportion of HBV-HIV-coinfected patients with detectable viraemia on 3TC-containing ART had resistance mutations despite good ART adherence as determined by HIV RNA suppression. This study emphasizes the need for dual therapy as part of a fully suppressive ART in all HBV-HIV-coinfected patients in Ghana.

Epidemiological characteristics of the carriers with coexistence of HBsAg and anti-HBs based on a community cohort study

The coexistence of HBsAg and anti-HBs is an atypical serological pattern in HBV infection. There is no epidemiological characteristics of this serological pattern in the community and there is controversy over the molecular mechanisms underlying this pattern. We investigated the epidemiological characteristics of the carriers with HBsAg and anti-HBs in a longitudinal community cohort study. The prevalence of this atypical serological pattern was 2.93% (122/4169) in HBsAg-positive populations. The prevalence progressively increased with age from 40 to 70 years old. The rate of HBeAg positive and detectable HBV DNA were both significantly higher in carriers with this pattern than in carriers who were HBsAg positive but anti-HBs negative (26/122 verse 598/4047, P = 0.046; 86/122 verse 275/529,P < 0.001). After 1 year of follow-up, 85.19% of the carriers still had coexistence HBsAg and anti-HBs, 14.81% of the carriers lost their anti-HBs. Viral sequencing showed that carriers with coexistence of HBsAg and anti-HBs had higher numbers of residue changes within the S gene than carriers who were HBsAg positive but anti-HBs negative (2.42 verse 1.33 changes per 100 residues, P < 0.05). Hence, the coexistence of HBsAg and anti-HBs is a unique serological pattern which may be associated with an increased risk of adverse clinical outcome and may be related to HBsAg immune variants which have genotypic heterogeneity.

Functional analysis of 'a' determinant mutations associated with occult HBV in HIV-positive South Africans

Occult hepatitis B is defined by the presence of hepatitis B virus (HBV) DNA in the absence of hepatitis B surface antigen (HBsAg). Occult HBV is associated with the development of hepatocellular carcinoma, reactivation during immune suppression, and virus transmission. Viral mutations contribute significantly to the occult HBV phenotype. Mutations in the 'a' determinant of HBsAg are of particular interest, as these mutations are associated with immune escape, vaccine escape and diagnostic failure. We examined the effects of selected occult HBV-associated mutations identified in a population of HIV-positive South Africans on HBsAg production in vitro. Mutations were inserted into two different chronic HBV backbones and transfected into a hepatocyte-derived cell line. HBsAg levels were quantified by enzyme-linked immunosorbent assay (ELISA), while the detectability of mutant HBsAg was determined using an HA-tagged HBsAg expression system. Of the seven mutations analysed, four (S132P, C138Y, N146D and C147Y) resulted in decreased HBsAg expression in one viral background but not in the second viral background. One mutation (N146D) led to a decrease in HBsAg detected as compared to HA-tag, indicating that this mutation compromises the ability of the ELISA to detect HBsAg. The contribution of occult-associated mutations to the HBsAg-negative phenotype of occult HBV cannot be determined adequately by testing the effect of the mutation in a single viral background, and rigorous analysis of these mutations is required.

Molecular mechanisms underlying HBsAg negativity in occult HBV infection

Although genomic detection is considered the gold standard test on HBV infection identification, the HBsAg investigation is still the most frequent clinical laboratory request to diagnose HBV infection in activity. However, the non-detection of HBsAg in the bloodstream of chronic or acutely infected individuals has been a phenomenon often observed in clinical practice, despite the high sensitivity and specificity of screening assays standardized commercially and adopted in routine. The expansion of knowledge about the hepatitis B virus biology (replication/life cycle, genetic variability/mutability/heterogeneity), their biochemical and immunological properties (antigenicity and immunogenicity), in turn, has allowed to elucidate some mechanisms that may explain the occurrence of this phenomenon. Therefore, the negativity for HBsAg during the acute or chronic infection course may become a fragile or at least questionable result. This manuscript discusses some mechanisms that could explain the negativity for HBsAg in a serological profile of individuals with HBV infection in activity, or factors that could compromise its detection in the bloodstream during HBV infection.

Seroepidemiology and occult hepatitis B virus infection in young adults in Banjarmasin, Indonesia

Hepatitis B virus (HBV) infection remains a public health problem in Indonesia. There has been limited data regarding HBV infection in young adult population. This study aimed to evaluate the seroepidemiology of HBV infection and characterize occult HBV variants in healthy young adults in Banjarmasin, Indonesia, who were born before the implementation of the universal infant hepatitis B vaccination. Serum samples of 195 healthy young adults were tested for HBsAg, anti-HBc, and anti-HBs. The prevalence of HBsAg, anti-HBc, and anti-HBs was 9 (4.6%), 62 (31.8%), and 96 (49.2%), respectively. Seventy four (37.9%) samples were seronegative for all three parameters, indicating the susceptibility to HBV infection. Among 66 samples positive for HBsAg and/or anti-HBc, 13 (19.7%) were HBV DNA positive; of these, four were HBsAg positive and nine were HBsAg negative, and categorized as occult HBV infection. Most occult HBV cases had high-level anti-HBs (>100 IU/l), suggesting that blood with positive anti-HBs and anti-HBc could not be regarded as noninfectious. Thirteen amino acid substitutions were identified: T126S, P127S, Q129R, T131N, M133T, and Y161S in the HBsAg-positive group; P120T, T126I, G145S, Y161F, E164V, and V168F in the occult-HBV group; and T143S in both groups. More studies are required to provide data on the prevalence and characteristics of mutants to ensure reliable diagnosis. The occult HBV infection, combined with the HBsAg prevalence, could indicate the high HBV carriage among young adults in this area. The high percentage of individuals susceptible to HBV infection reiterates the need for catch-up immunization strategies targeted at young adults.

Analysis of residual perinatal transmission of hepatitis B virus (HBV) and of genetic variants in human immunodeficiency virus and HBV co-infected women and their offspring

BACKGROUND

Despite implementation of universal infant hepatitis B (HB) vaccination, mother-to-child transmission (MTCT) of hepatitis B virus (HBV) still occurs. Limited data are available on the residual MTCT of HBV in human immunodeficiency virus (HIV)-HBV co-infected women.

OBJECTIVES

We assessed the prevalence of HBV infection among HIV-infected pregnant women and the rate of residual MTCT of HBV from HIV-HBV co-infected women and analyzed the viral determinants in mothers and their HBV-infected children.

STUDY DESIGN

HIV-1 infected pregnant women enrolled in two nationwide perinatal HIV prevention trials in Thailand were screened for HB surface antigen (HBsAg) and tested for HBeAg and HBV DNA load. Infants born to HBsAg-positive women had HBsAg and HBV DNA tested at 4-6 months. HBV diversity within each HBV-infected mother-infant pair was analyzed by direct sequencing of amplified HBsAg-encoding gene and cloning of amplified products.

RESULTS

Among 3312 HIV-1 infected pregnant women, 245 (7.4%) were HBsAg-positive, of whom 125 were HBeAg-positive. Of 230 evaluable infants born to HBsAg-positive women, 11 (4.8%) were found HBsAg and HBV DNA positive at 4-6 months; 8 were born to HBeAg-positive mothers. HBV genetic analysis was performed in 9 mother-infant pairs and showed that 5 infants were infected with maternal HBV variants harboring mutations within the HBsAg "a" determinant, and four were infected with wild-type HBV present in highly viremic mothers.

CONCLUSIONS

HBV-MTCT still occurs when women have high HBV DNA load and/or are infected with HBV variants. Additional interventions targeting highly viremic women are thus needed to reduce further HBV-MTCT.

Gender disparity in distribution of the major hydrophilic region variants of hepatitis B virus genotype C according to hepatitis B e antigen serostatus

Hepatitis B virus (HBV) e antigen (HBeAg) seroconversion during chronic HBV infection is known to play an important role in disease progression and patient response to antiviral agents. The aim of the present study was to analyze gender disparity in distribution of major hydrophilic region (MHR) variants according to HBeAg serostatus. Prevalence of MHR variants from 68 Korean patients with chronic hepatitis (31 HBeAg-positive and 37 HBeAg-negative) was examined in terms of HBeAg serostatus and sex by direct sequencing analysis of the MHR. Gender disparity was observed in the distribution of MHR variants according to HBeAg serostatus. In male patients, the prevalence of MHR variants was significantly higher in HBeAg negative patients than in HBeAg positive patients [58.8% (10/17 patients) vs. 14.3% (3/21 patients), P=0.004]. However, the same was not true in female patients [55.0% (11/20 patients) vs. 60.0% (6/10 patients), P=1.000)]. In addition, 2 mutation types (L110I and G145A) related to HBeAg serostatus were found. In conclusion, HBeAg seroconversion in male chronic patients infected with genotype C could lead to mutations of MHR, major target to host immune response, which might in turn contribute to HBV persistence and immune evasion.

Hepatitis B virus S gene escape mutants

Hepatitis B virus (HBV) can be classified into nine immunological subtypes or eight genotypes. The most prevalent genotypes in Asia are genotypes B and C. HBV is transmitted parenteraly and can produce either asymptomatic or symptomatic disease. Although the consequences of acute hepatitis B can be severe, serious sequelae are associated with chronic infections. HBV seroprevalence ranges from intermediate (2%-7%) to high (≥8%) levels in Asia. Several strategies for the control and prevention of HBV infection have been found to be efficacious. They include vaccination and the administration of HBIG, interferon-a and nucleoside/nucleotide analogues. However, these procedures also apply selective pressures on HBV in infected individuals leading to the generation and accumulation of mutations in the S gene. Most of these mutations occur in the major hydrophilic region (MHR) of the S gene. These mutations create public health concerns as they can be responsible for reactivation of hepatitis B and occult hepatitis B infection. The inability to detect occult infections means that these individuals may become blood donors. This suggests that new strategies for donor evaluation and selection may need to be developed to protect the blood supply.

Serologic and molecular characteristics of hepatitis B virus among school children in East Java, Indonesia

Universal childhood hepatitis B vaccination was introduced in Indonesia in 1997; by 2008, coverage was estimated to be 78%. This study aimed to investigate the serologic status and virologic characteristics of hepatitis B virus (HBV) among the children in East Java. A total of 229 healthy children born during 1994-1999 were enrolled in this study. Overall, 3.1% were positive for hepatitis B surface antigen (HBsAg) and 23.6% were positive for antibody to HBsAg (anti-HBs). HBV DNA was detected in 5 of 222 HBsAg-negative carriers, which were suggested to be cases of occult HBV infection. A single amino substitution (T126I) in the S region was frequently found. HBV infection remains endemic, and the prevalence of anti-HBs remains insufficient among children in East Java, Indonesia.

Evidence of Long-Term Suppression of Hepatitis B virus DNA by Tenofovir as Rescue Treatment in Patients Coinfected by HIV

Background

The efficacy of long-term hepatitis B virus (HBV) treatment with tenofovir (TDF) in relation to lamivudine (LMV) resistance in HIV patients failing on LMV deserves further investigations.

Methods

HIV–HBV coinfected patients were selected, provided that LMV was included in the first highly active antiretroviral therapy regimen and TDF was subsequently introduced.

Results

Forty HIV–HBV patients were included, 25 had undetectable HBV DNA on LMV and 15 were failing on LMV treatment. Three cases of triple 173V+180M+ 204V HBV reverse transcriptase (rt) mutants were identified, as well as several mutations or polymorphisms in the surface antigen gene at positions possibly correlating with vaccine escape. A new mutation (rtI233V) was found in one adefovir-naive patient. In 10 patients, uninterrupted TDF treatment led to a sustained treatment response for a median of 160 (interquartile range 111–189) weeks. Two patients underwent intermittent treatment with TDF and LMV, responding any time TDF was reintroduced. In one patient, TDF without LMV provided treatment response. One patient did not respond to TDF because of low treatment adherence. One patient infected with the triple rt mutant did not respond to entecavir, but TDF was successful as rescue.

Conclusions

Combination therapy with TDF was effective against HBV mutant viruses resistant to LMV and provided sustained control of HBV replication over long-term follow-up, even after entecavir failure. Moreover, suppression of HBV vaccine escape variants could provide important benefits from a public health perspective.

Clinical and virological significance of the co-existence of HBsAg and anti-HBs antibodies in hepatitis B chronic carriers

The co-existence of hepatitis B surface antigen (HBsAg) and anti-HBs antibodies (HBsAb) in serum of hepatitis B virus (HBV)-chronic carriers has been previously associated with HBsAg-amino acid (aa) substitutions. However, the aa pattern of HBV-reverse transcriptase (RT) and the clinical settings associated with this serological profile remain largely unknown. We studied thirteen HBsAg-positive/HBsAb-positive patients. Newly diagnosed HBsAg-positive/HBsAb-negative patients (n=51) served as controls. HBsAg/RT sequences were obtained using in-house protocols. HBsAg-positive/HBsAb-positive patients were predominantly immunosuppressed (69%). Five presented advanced liver fibrosis. HBV DNA >5.0 log(10) copies/ml was significantly more frequent than in controls. A significantly higher aa variability was observed versus controls within HBsAg major hydrophilic region (MHR), especially the a-determinant, and within RT for regions overlapping the MHR, the a-determinant, and HBsAg C terminal region where drug resistance mutations occur. Further studies are needed to determine whether this higher HBsAg/HBV-RT variability might favor dissemination of anti-HBsAb escape HBV mutants and concomitantly alter nucleos(t)ide analogs efficacy.

[Microbiological diagnosis of viral hepatitis]

Hepatitis of viral aetiology caused by hepatotropic virus (A, E, B, D and C) represents an important work load for the clinical virology laboratory. Most of the diagnostic is based upon detection in serum and plasma samples of different serological and virological markers, which correlates with different infection stages. In chronic infection by HBV and HCV is necessary to perform diagnostic by molecular methods as well as antigen detection in sequential samples along the course of the disease taking into account that a reliable storage must be provided for stability of structural components of the virus. Recent knowledge about mutations variants in some of the virus may alter the validity of particular markers.

Frequency of hepatitis B virus 'a' determinant variants in unselected Spanish chronic carriers

The prevalence in the population of hepatitis B virus (HBV) surface antigen (HBsAg) variants that may impair diagnosis, or allow the virus to escape vaccine-induced immunity or passive immunoglobulin therapy is unknown. A genome fragment encoding HBsAg amino acids 112-212 was amplified and sequenced from the sera of 272 unselected DNA-positive, HBV-chronic carriers from Spain. The genotype and the HBsAg subtype were predicted from the sequences. Analysis of amino-acid positions 112-157 revealed single or multiple substitutions in 39% of the carriers studied. Mutations were not detected for residues 121, 135, 137, 139, 140, 141, 142, 146, 147, 148, 149, 151, 152, 153, 155, 156, and 157. Substitutions reported previously to be in association with failures of diagnostic tests or with vaccine or immunoglobulin therapy escape were found in 12.5%, 6.6%, and 9.2% of carriers, respectively. Met133Thr (2.2%); Gln129His, Met133Ile, Phe/Tyr134Asn (1.8%); Phe/Tyr134Leu, Gly145Ala (1.5%), and Pro120Thr (1.1%) were the most frequent. Other substitutions, including Gly145Arg (0.4%), were found at a frequency of less than 1%. Samples containing HBV mutants were tested with three commercial assays for HBsAg screening. Almost all the mutants reacted to the upper cut-off values of the assays, but six samples with weak reactivity with one or more of the methods were also found. Thus, HBV mutants with a potential impact on clinical and public health issues are moderately frequent among chronic carriers from Spain, although their influence on the performance of diagnostic tests seems to be slight.

Characteristics of drug resistant HBV in an international collaborative study of HIV-HBV-infected individuals on extended lamivudine therapy

BACKGROUND

Little is known about the prevalence and pattern of hepatitis B virus (HBV) mutations in HIV/HBV co-infected individuals on long-term lamivudine (3TC) therapy.

METHODS

HBV polymerase/envelope/basal core promoter/pre-core sequences from 81 HIV-HBV co-infected persons who received at least 6 months 3TC were compared to HBV reference sequences. Host and viral characteristics associated with HBV mutations were determined.

RESULTS

HBV viraemia was detected in 53 persons (65%) and was associated with lower CD4 cell count nadir and higher HIV RNA at the time of testing but not with 3TC duration. Known 3TC-resistant mutations occurred in 50% and 94% of viremic patients with < 2 years and > 4 years 3TC, respectively. The CD4 cell count at testing was significantly higher in those with 3TC-resistant mutations. The triple polymerase mutant (rtL173V, rtL180M, rtM204V), which behaves as a vaccine escape mutant in vitro, occurred in 17% of viraemic patients. Polymerase mutations that may confer resistance to other anti-HBV agents were also detected.

CONCLUSIONS

In HIV-HBV co-infected patients, greater immunocompromise is associated with continued HBV viraemia while on 3TC, and development of 3TC-resistant mutations are inevitable with prolonged 3TC use. These mutant viruses may limit future therapeutic options due to cross-resistance or may produce HBV vaccine escape mutants. Thus, timing and selection of antiretroviral therapy is critical in this population.

Hepatitis B virus genetic diversity

Hepatitis B virus (HBV) is a human DNA virus, which replicates through an RNA intermediate because of the reverse-transcriptase (RT) activity of its DNA polymerase. As a result, the mutation rate for HBV is higher than the rate observed for most DNA viruses. HBVs are classified into genotypes based on genomic sequencing, and antigenic subtypes based on the antigenic properties of its major surface glycoprotein, the HBV surface antigen (HBsAg). Subgenotypes have been identified within most of the HBV genotypes. The HBV groups defined by the different genotype-HBsAg subtype associations found over the world display characteristic geographical distributions, reflecting the movements of human populations and other epidemiologically significant events. Such HBV groups constitute genetically stable viral populations sharing a common evolutionary history, but additional stable changes, originating from mutation and mutant selection, are observed within all of them. These viral sub-populations are known as the HBV variants, and some of which have medical and public health relevance. Pre-core (pre-C) defective variants have been shown to make HBV infection much less susceptible to interferon treatment, and treatment failures with other antiviral drugs have been associated with selection of resistant variants that display specific mutations in the genome region encoding the viral RT activity. Since the RT region of the genome overlaps the sequence encoding the HBsAg molecule, selection of drug resistant variants involves, in some cases, the indirect selection of HBsAg variants. Viral variants displaying changes in HBsAg seem to be very common among chronic HBV carriers; and some of these variants may emerge under the pressure of the neutralizing antibody response, leading to vaccine resistance and resistance to immunotherapy. Mutations conferring resistance to immunotherapy are noted often among liver transplant recipients and among babies born to HBV-carrier mothers. In addition, some of these HBsAg variants have been associated with lack of detection by HBsAg tests used for the diagnosis of HBV infection, for the identification of chronic carriers, for screening of blood donations for transfusion, and in the manufacture of therapeutic blood products.

Replicative homeostasis II: influence of polymerase fidelity on RNA virus quasispecies biology: implications for immune recognition, viral autoimmunity and other "virus receptor" diseases

Much of the worlds' population is in active or imminent danger from established infectious pathogens, while sporadic and pandemic infections by these and emerging agents threaten everyone. RNA polymerases (RNA_pol) generate enormous genetic and consequent antigenic heterogeneity permitting both viruses and cellular pathogens to evade host defences. Thus, RNA_pol causes more morbidity and premature mortality than any other molecule. The extraordinary genetic heterogeneity defining viral quasispecies results from RNA_pol infidelity causing rapid cumulative genomic RNA mutation a process that, if uncontrolled, would cause catastrophic loss of sequence integrity and inexorable quasispecies extinction. Selective replication and replicative homeostasis, an epicyclical regulatory mechanism dynamically linking RNApol fidelity and processivity with quasispecies phenotypic diversity, modulating polymerase fidelity and, hence, controlling quasispecies behaviour, prevents this happening and also mediates immune escape. Perhaps more importantly, ineluctable generation of broad phenotypic diversity after viral RNA is translated to protein quasispecies suggests a mechanism of disease that specifically targets, and functionally disrupts, the host cell surface molecules – including hormone, lipid, cell signalling or neurotransmitter receptors – that viruses co-opt for cell entry. This mechanism – "Viral Receptor Disease (VRD)" – may explain so-called "viral autoimmunity", some classical autoimmune disorders and other diseases, including type II diabetes mellitus, and some forms of obesity. Viral receptor disease is a unifying hypothesis that may also explain some diseases with well-established, but multi-factorial and apparently unrelated aetiologies – like coronary artery and other vascular diseases – in addition to diseases like schizophrenia that are poorly understood and lack plausible, coherent, pathogenic explanations.

Overlapping gene mutations of hepatitis B virus in a chronic hepatitis B patient with hepatitis B surface antigen loss during lamivudine therapy

Disappearance of hepatitis B surface antigens (HBsAg) in chronic hepatitis B usually indicates clearance of hepatitis B virus (HBV) infection. However, false HBsAg negativity with mutations in pre-S2 and 'a' determinant has been reported. It is also known that YMDD mutations decrease the production of HBV and escape detection of serum HBsAg. Here, we report overlapping gene mutations in a patient with HBsAg loss during the lamivudine therapy. After 36 months of lamivudine therapy in a 44-yrold Korean chronic hepatitis B patient, serum HBsAg turned negative while HBV DNA remained positive by a DNA probe method. Nucleotide sequence of serum HBV DNA was compared with the HBV genotype C subtype adr registered in NCBI AF 286594. Deletion of nucleotides 23 to 55 (amino acids 12 to 22) was identified in the pre-S2 region. Sequencing of the 'a' determinant revealed amino acid substitutions as I126S, T131N, M133T, and S136Y. Methionine of rtM204 in the P gene was substituted for isoleucine indicating YIDD mutation (rtM204I). We identified a HBV mutant composed of pre-S2 deletions and 'a' determinant substitutions with YMDD mutation. Our result suggests that false HBsAg negativity can be induced by combination of overlapping gene mutations during the lamivudine therapy.

Antigenic and immunogenic changes due to mutation of s gene of HBV

AIM: To investigate the change of immunological characteristics of HBsAg caused by the mutation at codon 145 of HBsAg using DNA-based immunization.

METHODS: Plasmids expressing mutant and wild type envelope antigens were transfected into human hepatocellular carcinoma cellsviaelectrotransformation. The antigenicity of HBsAg was studied with EIA and immunocytochemical staining. Then plasmids were used to immunize 5 C57BL/6 mice. Sera of mice were detected for anti-HBs and anti-preS2 with ELISA.

RESULTS: The mutant HBsAg could be detected by native antibody in EIA and immunocytochemical study. But the A_{(450 nm)} value of the mutant HBsAg in the supernatant was apparently lower than that of the wild-type. Both mutant and native HBsAg expression plasmid could stimulate a strong humoral immune response to HBsAg and preS2 antigen in mice. Protective antibodies against HBsAg elicited by the native HBsAg occurred earlier than that elicited by the mutant HBsAg about one to two weeks. The occurrence of protective antibodies against preS2 antigen was one to two weeks earlier than that of anti-HBs.

CONCLUSION: The amino acid substitution causes changes of the antigenicity and immunogenicity of HBsAg, but mutant HBsAg can still induce a protective humoral immune response in mice.

Replication and gene expression of mutant hepatitis B virus in a transgenic mouse containing the complete viral genome with mutant s gene

AIM: To establish the transgenic mouse line harbouring complete hepatitis B virus (HBV) genome with mutant s gene (adr subtype).

METHODS: Transgenic mice were generated by microinjecting HBV genome into fertilized eggs. Integration, expression, replication of HBV gene and histological changes in transgenic mice were estimated by genomic DNA PCR, serum DNA PCR, Southern blot, ELISA, HE staining, immunohistochemistry and transmission electron microscopy. Transgenic mice with HBsAg positive in serum were bred and analyzed.

RESULTS: A total of 288 eggs survived from microinjections were transplanted into the oviducts of 13 pseudopregnant mice and 49 pups were produced. Twenty-six mice were identified to have the integrated HBV gene. Serum HBsAg and HBeAg were detected in 2 of 43 mice. HBsAg and HBcAg in cytoplasm or nuclei of hepatocytes were detected in 10 mice. Founders with HBsAg in serum were named lineages G145R-15 and G145R-18. Of the 16 F1 offsprings generated by G145R-15 founder, 12 were positive for HBV genome with PCR, 10 were positive for HBsAg and HBcAg with immunohistochemistry and 7 were positive for HBsAg and HBeAg with ELISA. Only 1 of 8 F1 offsprings generated by G145R-18 founder was survived and it was detected positive for HBV genome, HBsAg, HBcAg and HBeAg. Both of the two lineages had some pathological characteristics of mild chronic hepatitis B in the liver, such as swelling of hepatocytes and focal hepatocellular necrosis and parenchymal lymphomononuclear cell infiltrate.

CONCLUSION: Transgenic mice harbouring HBV with mutant s gene can be generated. The HBV genes are integrated in the transgenic mice genome and can be expressed, replicated, packaged and excreted. HBV DNA can be stably transmitted in the transgenic mice.

Hepatitis B virus (HBV) vaccine-induced escape mutants of HBV S gene among children from Qidong area, China

Hepatitis B virus (HBV) infection is the main factor, which induces hepatocellular carcinoma (HCC) in Qidong high-risk area, China. To prevent HBV infection is the most important strategy to inhibit the HCC carcinogenesis. A large project was performed in Qidong area to protect newborn babies from the HBV infection that 80,000 children born between 1984 and 1990 were vaccinated. After three times of follow-up studies, 15 screened children were found to have symptoms of illness showing persistent elevation of serum glutamic-pyruvic transaminase (ALT). From these previously collected data, we found that the ALT levels of five vaccinees with negative hepatitis B surface antigen (HBsAg) were significantly higher than those of 10 vaccinees with positive HBsAg. Furthermore, with the passage of time, the difference of ALT levels between the two groups (HBsAg negative and positive groups) diminishes. After cloning and sequencing of the HBsAg "a" epitope coding sequences, we found that mutations in "a" epitope were correlated with the absence of detectable anti-HBsAg, while no mutations were seen in the anti-HBsAg positive infections. We also found that majority of point mutations were occurred in the coding sequences of the first loop structure in "a" epitope. The structure of double loop conformation in "a" epitope was conservative, and important for HBV antigenicity. These changes in a double loop conformation would escape neutralization by vaccine-induced antibody.

Construction and analysis of HBV S gene clones with artificial mutation sites

AIM

To study the mutation in a determinant of HBV S gene, to explore how it influenced the biologic characteristics of S gene.

METHODS

Through site-mutation PCR, we constructed series variant clones (T126S, M133L, T144A) of HBV S gene 'a' determinant according to epidemiologic data.

RESULTS

After analysis of sequence and expression of cells, sequences of mutation clone were correct and the mutation of different positions in 'a' determinant could influence antigenicity of expressed HBsAg.

CONCLUSION

The successful construction and expression of variant clone provide the theoretical basis for developing new detection kit, HBV vaccine and HBIG.