Surface gene mutations of hepatitis B virus among high-risk patients with occult hepatitis B virus infection

Mutations in the S gene of hepatitis B virus in three generations of patients with chronic hepatitis B

Failure to neutralize HBsAg and subsequent escape from the host immune system may be caused by HBsAg mutations, particularly in the "a" determinant, which alters the antigenicity of the protein. The purpose of this study was to examine the frequency of S gene mutations in three generations of HBV cases in northeastern Iran. In this study, 90 patients with chronic HBV were assigned to three groups according to the inclusion criteria. The plasma were utilized to extract viral DNA, and the PCR was applied. Direct sequencing and alignment were performed on the S gene, using reference sequence. The results indicated that all HBV genomes were categorized as the genotype D/ayw2. Among 79 point mutations detected, 36.8% were silent, and 56.2% were missense. In the S region, mutations were observed in 88.9% of CHB subjects studied. In the three-generation group, 21.5% of mutations were in the "a" determinant, and 2.6%, 19.5%, and 87.0% of these mutations were observed in antigenic epitopes of CTLs, CD4+, and B cells, respectively. In addition, 56.7% of mutations occurred at Major Hydrophilic Region. S143L and G145R mutations which the most prevalent in the three-generation (36.7%, 20%), and two-generation (42.5%, 20%) groups, related to the failure of HBsAg detection, vaccine, and immunotherapy escape. The findings showed that most of the mutations were concentrated in the B cell epitope. Most CHB cases from the three-generation, especially grandmothers, had HBV S gene mutations and subsequent amino acid mutations, suggesting that these mutations may be critical for pathogenesis and vaccine evasion.

Occult hepatitis B virus infection in immunized children born to carrier mothers

BACKGROUND

The prevalence of occult hepatitis B virus (HBV) infection (OBI) in children due to mother-to-child transmission (MTCT) despite immunoprophylaxis remains controversial and is still unknown in Japan. The aim of this study was to determine the OBI prevalence in such children in Japan and identify the genomic mutations that might be associated with the pathogenesis of OBI in children.

METHODS

The data on 158 children born to HBV carrier mothers and who received complete passive-active immunoprophylaxis after birth in 2002-2014 were reviewed. HBV markers were detected using commercial enzyme-linked immunosorbent assay kits. HBV-DNA was detected using real-time and nested polymerase chain reaction. Complete genomic sequences were determined.

RESULTS

Among the 158 children studied, three had HBV MTCT: two had OBI, and one had resolved HBV infection (RBI). The prevalence of OBI and RBI was estimated to be 1.3% and 0.6%, respectively. The HBV genomes of the two OBI children were wild type and 100% identical to those of their mothers. Of these two children, one received repeated hepatitis B immunoglobulin (HBIG) and developed overt HBV infection. Her HBV genome had a G145R mutation in the S gene that might have been induced by HBIG treatment. The RBI child was persistently positive for antibody to HBV core antigen (10-12 signal/cut-off ratio; S/CO).

CONCLUSIONS

A low prevalence of OBI was observed in children who received immunoprophylaxis for preventing MTCT in Japan. The development of overt HBV infection in infants with OBI indicates the necessity of close and long-term monitoring.

Impact of "a" determinant mutations on detection of hepatitis B surface antigen (HBsAg) in HBV strains from Chinese patients with occult hepatitis B

This study was designed to detect mutations that occur within the "a" determinant in the S gene of the hepatitis B virus (HBV) in patients with occult hepatitis B (OHB), and to analyze the influence of these mutations on expression and reactivity of the hepatitis B surface antigen (HBsAg). Twenty-three certified OHB samples were compared to 32 HBsAg positive samples from patients with chronic hepatitis B. The median HBV DNA levels in the OHB group were significantly lower than those in the control group (P < 0.0001). Mutations within the "a" determinant were analyzed by gene amplification and sequencing. This revealed mixed infections in which clones within a sample displayed either different mutations or mutations in association with clones that exhibited wild type amino acid patterns. Sequencing analysis also showed a significant difference between the proportions of amino acid mutations observed in the OHB and control groups. Seven recombinant S (rS) proteins with corresponding OHB mutations and three wild type alleles were expressed and purified in the Pichia pastoris expression system to preserve conformational attributes, and their reactivity analyzed using six commercial HBsAg assays. The OHB sera were HBsAg nonreactive while the rS proteins with corresponding OHB mutations were universally reactive. Thus, we postulate that the reduced binding affinity between mutated HBsAg and its antibody may not be as important in defining OHB as is the effect of specific mutations in the preS/S region of the genome that affect the synthesis and secretion of the S protein and/or the virion.

Occult hepatitis B virus infection and S gene escape mutants in HIV-infected patients after hepatitis B virus vaccination

Hepatitis B virus (HBV) vaccination is recommended for HIV patients. Despite the relative success of HBV vaccination, breakthrough infections can occur infrequently in patients, and it can be due to occult HBV infection, vaccine unresponsiveness and/or emergence of escape mutants. This study assessed the presence of occult HBV infection and S gene escape mutants in HIV-positive patients after HBV vaccination. Ninety-two HIV-positive patients were enrolled in this study, including 52 responders to HBV vaccine and 40 non-responders. All of the cases received HBV vaccine according to routine HBV vaccination protocols. The presence of HBV-DNA was determined by real-time polymerase chain reaction (PCR). In HBV-DNA positive samples, the most conserved regions of S gene sequences were amplified by nested PCR and PCR products were sequenced. Occult HBV infection was detected in two cases. Glycine to arginine mutation at residue 145 (G145R) within the ‘a’ region of the S gene was detected in one of the occult HBV infection cases who was in the non-responder group. This study showed that the prevalence of occult HBV infection and vaccine escape mutants was low in our HBV-vaccinated HIV-positive patients in both responder and non-responder groups, so there was no alarming evidence indicating breakthrough HBV infection in our vaccinated HIV-positive cases.

Characterization of Occult Hepatitis B Infection Among Injecting Drug Users in Tehran, Iran

BACKGROUND

Hepatitis B virus (HBV) infection is a major health problem worldwide.

OBJECTIVES

The aim of this study was to investigate the frequency of occult hepatitis B infection (OBI) and its associated risk factors, together with the molecular characterization of the virus in injecting drug users of Tehran.

PATIENTS AND METHODS

The study consisted of 229 injecting drug users. Serum samples were collected and tested for the presence of hepatitis B core antibody (HBcAb) and hepatitis B surface antigen (HBsAg) by an enzyme-linked immunosorbent assay (ELISA). HBV B virus DNA was extracted from the serum samples, and a fragment of the S gene was amplified using the nested polymerase chain reaction. The genotype, subgenotypes, subtype, and S gene mutation of HBV were determined by direct sequencing. A phylogenetic tree was constructed using the neighbor-joining method.

RESULTS

Sixty-four (28%) participants were HBcAb positive, 59 cases were HBcAb positive and HBsAg negative, and 5 cases were HBsAg positive. Hepatitis B DNA was found in three HBsAg-positive cases. Thirteen of 59 (22%) individuals were hepatitis B DNA positive. The phylogenetic tree of hepatitis B DNA showed the existence of genotype D. The only significant correlation was between sharing a syringe and OBI.

CONCLUSIONS

In comparison with the rate of HBcAb positivity reported in other Iranian studies, the rate was higher in the present study. There were a few variations, genotypes, and subtypes among the infected injecting drug users. Further investigations are needed to unravel the molecular characterization of OBI.

Clinical significance of hepatitis B surface antigen mutants

Hepatitis B virus (HBV) infection is a major public health problem in many countries, with nearly 300 million people worldwide carrying HBV chronic infection and over 1 million deaths per year due to cirrhosis and liver cancer. Several hepatitis B surface antigen (HBsAg) mutations have been described, most frequently due to a single amino acid substitution and seldom to a nucleotide deletion. The majority of mutations are located in the S region, but they have also been found in the pre-S1 and pre-S2 regions. Single amino acid substitutions in the major hydrophilic region of HBsAg, called the "a" determinant, have been associated with immune escape and the consequent failure of HBV vaccination and HBsAg detection, whereas deletions in the pre-S1 or pre-S2 regions have been associated with the development of hepatocellular carcinoma. This review article will focus on the HBsAg mutants and their biological and clinical implications.

Molecular Characterization of Pre-Core/Core and S Region of Hepatitis B Virus in Hemodialysis Patients With Occult Hepatitis B Infection

BACKGROUND

Occult hepatitis B infection (OBI) is a major public health problem worldwide, which harbors potential risk of hepatitis B virus (HBV) transmission through blood transfusion and transplantation. OBI is characterized by the presence of HBV-DNA in the blood or liver tissue without detectable hepatitis B surface antigen (HBsAg) in the serum. An important cause of OBI is the occurrence of mutations in the HBV genome, especially in the S region.

OBJECTIVES

The study aims to analyze mutations in S and pre-core/core regions of HBV-DNA in hemodialysis patients.

PATIENTS AND METHODS

Sera of 216 hemodialysis patients were tested for HBsAg and hepatitis B core antibody (HBcAb) by ELISA. Sera of patients that tested negative for HBsAg were evaluated by PCR for the detection of HBV-DNA in the S and pre-core/core regions. In total, six PCR products were sequenced, aligned, and compared with the HBV reference sequence. Amino acid deletion and nucleotide substitution were considered mutations in S and pre-core/core regions of HBV-DNA.

RESULTS

Among 216 patients, 203 (93.98%) and 175 (81.01%) sera samples tested negative for HBsAg and HBcAb, respectively. Among all HBsAg-negative samples, six (2.9%) tested positive for HBV-DNA, including four (1.97%) for S and two (0.98%) for pre-core regions. All four (1.97%) samples that tested positive for the S region belonged to HBV-subtype awy. The amino acid sequence of all four samples showed the YMDD motif in position 204 (rtM204). There were three amino acid substitutions in the S region (T127P, P153L, and F170S) and one substitution in the RT region (Y135S). Moreover, two (0.98%) pre-core/core positive patients had an unexpected stop codon in position 1896.

CONCLUSIONS

This study indicates that 2.9% of hemodialysis patients had OBI, which is considered as a major public health problem worldwide. Moreover, we observed three mutations in S region, including T127P, P153L, and F170S, which caused OBI. This study is first to report a mutation analysis of HBV in hemodialysis patients in southwestern Iran. These results indicate that current screening tests based on HBsAg detection are not reliable for detection of HBV infection in dialysis patients.

Viral hepatitis in hemodialysis: An update

Hepatitis outbreaks in hemodialysis (HD) patients and staff were reported in the late 1960s, and a number of hepatotropic viruses transmitted by blood and other body fluids have been identified. Hepatitis B virus (HBV) was the first significant hepatotropic virus to be identified in HD centers. HBV infection has been effectively controlled by active vaccination, screening of blood donors, the use of erythropoietin and segregation of HBV carriers. Hepatitis delta virus is a defective virus that can only infect HBV-positive individuals. Hepatitis C virus (HCV) is the most significant cause of non-A, non-B hepatitis and is mainly transmitted by blood transfusion. The introduction in 1990 of routine screening of blood donors for HCV contributed significantly to the control of HCV transmission. An effective HCV vaccine remains an unsolved challenge; however, pegylation of interferon-alfa has made it possible to treat HCV-positive dialysis patients. Unexplained sporadic outbreaks of hepatitis by the mid-1990s prompted the discovery of hepatitis G virus, hepatitis GB virus C and the TT virus. The vigilant observation of guidelines on universal precaution and regular virologic testing are the cornerstones of the effective control of chronic hepatitis in the setting of HD. Major recent advances in the viral diagnosis technology and the development of new oral, direct-acting antiviral agents allow early diagnosis and better therapeutic response. The current update will review the recent developments, controversies and new treatment of viral hepatitis in HD patients.

Occult hepatitis B virus infection in children born to HBsAg-positive mothers after neonatal passive-active immunoprophylaxis

BACKGROUND

Occult hepatitis B virus infection (OBI) is a well-recognized clinical entity characterized by the detection of HBV DNA in serum and/or liver in the absence of detectable HBsAg. Diagnosis of OBI requires a sensitive HBV DNA assay.

AIM

We aimed at determining the frequency of OBI in infants, born to HBsAg-positive mothers, who received immunoprophylaxis at birth.

METHODS

Sixty-four infants and children, born to HBsAg-positive mothers, who received hepatitis B immunoglobulin and HBV vaccine within 48 h after birth, were tested for HBV serological profile and HBV DNA by real-time PCR at least 1 month after last dose of HBV vaccine and not before 6 months of age.

RESULTS

The median age of the studied infants and children was 8 months, ranging from 6 to 132 months; 54.7 % were females. HBV DNA was detected in 2 infants. One case had OBI; she was negative for HBsAg, anti-HBc total, HBeAg and was positive for anti-HBs (titer 267 mIU/mL) with low level of viremia (HBV DNA 1.13 x 10(3) IU/mL). Another infant showed immunoprophylaxis failure with positive HBsAg, anti-HBc total, HBeAg, negative anti-HBe and anti-HBs; HBV viral load was 1.7 × 10(8) IU/mL. Both mothers were HBsAg and HBeAg-positive.

CONCLUSION

OBI may occur in infants born to HBsAg-positive mothers despite the receipt of immunoprophylaxis. OBI was detected in a low frequency in the present study. Anti-HBs positivity does not exclude OBI.

Hepatitis B virus Genotyping Among Patients With Cirrhosis

Background:

Hepatitis B virus (HBV) infection is a worldwide public health problem. Nine HBV genotypes (A-I) have been already discovered. HBV genotypes are important both in the clinical manifestation of disease and treatment response. Moreover, HBV DNA without HBs (Hepatitis B surface)-antigenemia was detected in some patients with chronic hepatitis (occult hepatitis). There is little information about HBV genotypes and its relation to occult infection despite the importance of this infection in Khuzestan Province.

Objectives:

This study aimed to determine both occult hepatitis B infection and HBV genotypes among cirrhotic patients.

Patients and Methods:

Thirty-eight patients with liver cirrhosis, including 11 (28.9%) HBsAg-positive patients and 27 (71.1%) patients with cryptogenic cirrhosis participated in this study. The mean age of the patients at the time of cirrhosis diagnosis was 54.85 years (range 26-75 years). All patients were anti-HCV and anti-HIV negative. For all the samples, the serological Enzyme-Linked Immunosorbent Assay (ELISA) was performed for HBV markers including HBsAg, HBcAb, HBeAg, HBeAb tests. The common primer of S region of HBV was used for Nested PCR. The PCR products of the positive individuals were sequenced for genotyping and subtyping of HBV.

Results:

Eleven (40.7%) out of 27 HBV cryptogenic cirrhosis and all 11 HBsAg-positive patients were positive for HBV DNA. The seroprevalences of Hepatitis B virus HBe antigen, anti-HBe and anti-HBc antibodies among the cryptogenic cirrhosis patients were 5 (18.5%), 1 (3.7%), and 5 (20.83), and among HBsAg-positive patients were 6 (54.5%), 5 (45.5%), and 7 (63.6%), respectively.

Conclusions:

In our study, only HBV genotype D was found among all the positive HBsAg and occult HBV infection. Moreover, high prevalence (40.7%) of occult HBV infection was determined among patients suffered from cryptogenic cirrhosis.

Mutations associated with occult hepatitis B in HIV-positive South Africans

Occult hepatitis B is characterized by the absence of hepatitis B surface antigen (HBsAg) but the presence of HBV DNA. Because diagnosis of hepatitis B virus (HBV) typically includes HBsAg detection, occult HBV remains largely undiagnosed. Occult HBV is associated with increased risk of hepatocellular carcinoma, reactivation to chronic HBV during immune suppression, and transmission during blood transfusion and liver transplant. The mechanisms leading to occult HBV infection are unclear, although viral mutations are likely a significant factor. In this study, sera from 394 HIV-positive South Africans were tested for HBV DNA and HBsAg. For patients with detectable HBV DNA, the overlapping surface and polymerase open reading frames (ORFs) were sequenced. Occult-associated mutations-those mutations found exclusively in individuals with occult HBV infection but not in individuals with chronic HBV infection from the same cohort or GenBank references-were identified. Ninety patients (22.8%) had detectable HBV DNA. Of these, 37 had detectable HBsAg, while 53 lacked detectable surface antigen. The surface and polymerase ORFs were cloned successfully for 19 patients with chronic HBV and 30 patients with occult HBV. In total, 235 occult-associated mutations were identified. Ten occult-associated mutations were identified in more than one patient. Additionally, 15 amino acid positions had two distinct occult-associated mutations at the same residue. Occult-associated mutations were common and present in all regions of the surface and polymerase ORFs. Further study is underway to determine the effects of these mutations on viral replication and surface antigen expression in vitro.

Absence of occult hepatitis B virus infection in sera of diabetic children and adolescents following hepatitis B vaccination

BACKGROUND

The prevalence of occult hepatitis B (HB) infection (OBI) in HB-vaccinated diabetic children has not yet been tested. Here, we aimed to determine the prevalence of OBI among HB-vaccinated children and adolescents with insulin-dependent diabetes mellitus (IDDM).

RESULTS

Eighty-seven (51.2%) children had a titer for antibodies to HB surface antigen (anti-HBs) of <10 IU/L. These included 44 (70%) IDDM children and 43 (40.2%) healthy children. Eighty-three (48.8%) children had an anti-HBs titer of ≥10 IU/L; they included 19 (30%) with IDDM and 64 (59.8%) healthy children. None of the enrolled children (n = 170) were reactive for total antibody to HB core antigen (anti-HBc) as determined by enzyme-linked immunosorbent assay. HB virus DNA was not detected in HB-vaccinated IDDM or healthy children and adolescents.

METHOD

An amount of 170 HBsAg-negative sera samples from HB-vaccinated children and adolescents was included. They were classified into the IDDM group (n = 63) and the healthy control group (n = 107). HBsAg, anti-HBc, and anti-HBs were tested by enzyme-linked immunosorbent assay, and HB virus DNA was tested by nested polymerase chain reaction using 3 pairs of surface, core, and X genes.

IN CONCLUSION

Primary HB vaccination confers long-term protection against OBI in Egyptian diabetic children and adolescents. However, the number of cases tested in this study was relatively low, and further studies and long-term follow-up of large populations are needed to draw solid and convincing conclusions.

Occult hepatitis B virus infection in anti-HBs-positive infants born to HBsAg-positive mothers in China

Objective

To investigate the prevalence of occult HBV infection (OBI) among children and to characterize virology of occult HBV, we conducted an epidemiological survey.

Methods

186 HB-vaccinated infants born to HBsAg-positive mothers were included in the study. Serological tests for HBV markers were performed using commercial ELISA kits. Real-time quantitative PCR and nested PCR were used to detect HBV DNA. PCR products of the C and pre-S/S regions were sequenced and analyzed.

Results

1.61% (3/186) infants were HBsAg positive, and 4.92% (9/183) infants were considered as occult infection. The viral load of mothers was associated with occult infection (P = 0.020). Incomplete three-dose injections of HB vaccine was associated with HBV infection (P = 0.022). Six OBI infants were positive for anti-HBs, but their titers were not greater than 100 mIU/mL. Seven isolated HBV pre-S/S sequences were obtained from nine OBI infants. Three of the sequences were genotype C, and four of the sequences were genotype C/D. Escape mutation S143L was found in the four sequences of genotype C/D. All seven sequences lacked G145R and other escape mutation in S region.

Conclusions

Occult HBV infection was detected in anti-HBs positive infants born to HBsAg-positive mothers in China. Occult infection was associated with absent anti-HBs or with low anti-HBs level, high maternal viral loads and escape mutations in the S gene.

Occult hepatitis B virus infection in hemodialysis patients: a concept for consideration

Hemodialysis patients potentially have an increased risk of infection with parenterally transmitted viral agents due to an impaired host immune response and multiple transfusion requirements. Viral hepatitis is considered as a problem for hemodialysis patients because 1.9% of all deaths among this population are related to the consequence of viral hepatitis. Hepatitis B virus (HBV) is one of the most important causes of transmitted infections by the parenteral route in hemodialysis patients. Occult HBV infection is characterized by presence of HBV infection without detectable hepatitis B surface antigen (HBsAg), which harbors potential risk of HBV transmission through hemodialysis. There are conflicting reports on the prevalence of occult HBV infection (OBI) in hemodialysis patients. Considering the importance of occult HBV infection in hemodialysis patients and the growing evidence on this subject, the purpose of this review is to provide comprehensive information on OBI prevalence in hemodialysis patients and highlight the most important points in this issue.

T cell responses and viral variability in blood donation candidates with occult hepatitis B infection

BACKGROUND & AIMS

Occult HBV infection (OBI) is defined by the presence of HBV DNA in the liver and/or serum and negative HBsAg testing. Since the implementation of highly sensitive HBV DNA screening, OBI is also detected in healthy blood donors. The aims of this study were to investigate HBV-specific immune responses and genetic variability in donors with OBI, established by HBV DNA in serum.

METHODS

HBV-specific T-cell responses to HBV antigens were tested in 34 OBI donors by IFN-γ ELISpot, cytometric bead array, and intracellular cytokine staining. As comparison populations, 36 inactive HBV carriers, 22 donors with spontaneously resolved HBV infection, 24 vaccinated donors, and 25 seronegative donors were also included. Surface, pre-S, and pre-c/core genes from 44 genotype D isolates (24 OBI and 20 HBsAg-positive) were sequenced.

RESULTS

The immune response of OBI donors to the 3 HBV antigens was 29-41%, similar to the response in subjects with resolved HBV infection and higher than that in HBsAg-positive subjects. On sequence analysis, OBI donors presented a higher HBsAg mutation rate than HBsAg-positive subjects. Mutations were clustered in the major hydrophilic region of HBsAg, and no stop codons or relevant mutations that could affect antigen formation or detection were observed.

CONCLUSIONS

Our results suggest that immune response can suppress viral replication to low levels and HBsAg expression to undetectable levels in OBI blood donors. Relevant mutations were not found in the genomic HBsAg coding region. Hence, the fact that HBsAg was not detected in OBI is likely due to low HBsAg production, rather than to a failure of laboratory reagents.