Selection of a precore mutant after vertical transmission of different hepatitis B virus variants is correlated with fulminant hepatitis in infants

Viral hepatitis and pregnancy

The management of viral hepatitis in the setting of pregnancy requires special consideration. There are five liver-specific viruses (hepatitis A, B, C, D, E), each with unique epidemiology, tendency to chronicity, risk of liver complications and response to antiviral therapies. In the setting of pregnancy, the liver health of the mother, the influence of pregnancy on the clinical course of the viral infection and the effect of the virus or liver disease on the developing infant must be considered. Although all hepatitis viruses can harm the mother and the child, the greatest risk to maternal health and subsequently the fetus is seen with acute hepatitis A virus or hepatitis E virus infection during pregnancy. By contrast, the primary risks for hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis D virus are related to the severity of the underlying liver disease in the mother and the risk of mother-to-child transmission (MTCT) for HBV and HCV. The prevention of MTCT is key to reducing the global burden of chronic viral hepatitis, and prevention strategies must take into consideration local health-care and socioeconomic challenges. This Review presents the epidemiology of acute and chronic viral hepatitis infection in pregnancy, the effect of pregnancy on the course of viral infection and, conversely, the influence of the viral infection on maternal and infant outcomes, including MTCT.

Successful Treatment of a South African Pediatric Case of Acute Liver Failure Caused by Perinatal Transmission of Hepatitis B

We report on the successful treatment of a South African infant with hepatitis B virus (HBV)-induced acute liver failure using lamivudine with no evidence of clinical resistance. Perinatal HBV transmission occurred despite timely HBV vaccination at 6, 10 and 14 weeks, as per South African vaccination schedule, highlighting the need to introduce the birth-dose HBV vaccine in South Africa.

Management of mother-to-child transmission of hepatitis B virus: Propositions and challenges

Chronic hepatitis B virus (HBV) infection due to mother-to-child transmission (MTCT) during perinatal period remains an important global health problem. Despite standard passive-active immunoprophylaxis with hepatitis B immunoglobulin (HBIG) and hepatitis B vaccine in neonates, up to 9% of newborns still acquire HBV infection, especially these from hepatitis B e antigen (HBeAg) positive mothers. Management of HBV infection in pregnancy still need to draw careful attention because of some controversial aspects, including the failure of passive-active immunoprophylaxis in a fraction of newborns, the effect and necessity of periodical hepatitis B immunoglobulin (HBIG) injection to the mothers, the safety of antiviral prophylaxis with nucleoside/nucleotide analogs, the benefit of different delivery ways, and the safety of breastfeeding. In this review, we highlight these unsettled issues of preventive strategies in perinatal period, and we further aim to provide an optimal approach to the management of preventing MTCT of HBV infection.

Hepatitis B genotypes, precore and core promoter mutants circulating in Tunisia

Hepatitis B virus (HBV) is characterized by genetic heterogeneity, including genotypes and mutations. Eight genotypes (A-H) have been identified throughout the world with a characteristic geographical distribution. Previous studies also suggest that the viral genotypes may correlate with differences in clinical features of the infection. Two types of mutations were particularly described, precore and basal promoter mutations; they may play an important role in the clinical outcome of HBV infection. The aim of this study was to investigate the prevalence of HBV genotypes and HBV variants in Tunisia, and their eventual association with severity of liver disease. Using a molecular method, HBV genotypes, precore and basal core promoter mutations were determined in 56 asymptomatic carriers and in 82 patients with histologically verified chronic liver disease and hepatocellular carcinoma (HCC). Three genotypes (D, A, and E) were detected; the prevalence was 80%, 8%, and 9%, respectively. No significant difference was observed for genotype D with clinical status. HBV mutants were detected in 93% of cases, precore mutants were the most prevalent. Basal core promoter mutants were observed in 61% of cases, they were frequently characterized by a double mutation in 1762 and 1764. Co-infection by these two types of mutants was detected in 50% of cases. Genotype D was the most prevalent HBV genotype in Tunisia. High circulation of precore and basal core promoter mutants are common in chronic hepatitis B infection in Tunisia.

The precore mutation is associated with severity of liver damage in Brazilian patients with chronic hepatitis B

BACKGROUND

The clinical relevance of the G1896A precore mutation in chronic hepatitis B is still poorly understood.

OBJECTIVES

To assess the frequency of G1896A precore mutation in Brazilian patients with chronic hepatitis B, as well as its relation to the viral genotype, serum HBV-DNA levels and liver damage.

STUDY DESIGN

Fifty chronic hepatitis B patients (29 HBeAg-negative and 21 HBeAg-positive) were studied. HBV-DNA was quantified by the Amplicor HBV Monitor test and precore region and S gene were amplified and submitted to automatic sequencing. The histological activity index (HAI), degrees of hepatic fibrosis and distribution of core antigen (HBcAg) in hepatocytes were determined.

RESULTS

Precore mutation occurred in 1/21 (4.8%) HBeAg-positive patients and in 17/29 (58.6%) HBeAg-negative (p < 0.0001). Genotype D was identified in 56.5%, genotype A in 41.3%, and genotype F in 2.2%. The frequency of genotypes D and A, as well as serum levels of ALT and HBV-DNA were similar in patients infected with wild type and with precore mutant. Patients infected with precore mutant presented a higher frequency of moderate/severe HAI (p: 0.03) and moderate/severe fibrosis and cirrhosis (p: 0.03) than those infected with wild type. There was no association between G1896A mutation and cytoplasmic expression of HBcAg.

CONCLUSIONS

Precore mutation was frequent among Brazilian subjects with chronic hepatitis B and its presence was associated with greater severity of liver disease.

Hepatitis B virus DNA during pregnancy and post partum: aspects on vertical transmission

Little is known about how pregnancy influences viremia levels in women with chronic hepatitis B virus infection. In this study, we first retrospectively analysed changes in HBV DNA levels during and after 55 pregnancies in HBsAg-positive women, of whom 9 were HBeAg-positive. Secondly, HBV DNA levels in 3 HBeAg-positive mothers whose babies became chronic HBV carriers, were compared with levels in 18 mothers whose babies were not infected by HBV. We found that HBV DNA ranged from 10(8.1) to 10(9.5) copies/mL in HBeAg-positive, and from undetectable (< 100) to 10(6.8) copies/mL in HBeAg-negative mothers. HBV DNA increased by a mean of 0.4 log late in pregnancy or early post partum; in 4 out of 16 HBeAg negative mothers by > 1 log during pregnancy. Post partum ALT increased in both HBeAg-positive and negative women. HBV DNA was 10(9.4)-10(10.4) copies/mL in 3 HBeAg-positive mothers whose babies were, as compared to < 100-10(10.4) copies/mL in 18 whose babies were not, vertically infected. Although the majority of HBeAg-negative women had low and relatively stable HBV DNA during pregnancy, viremia was also relatively high in some HBeAg-negative mothers, and both viremia and ALT increased significantly late in pregnancy or shortly after delivery. Vertical transmission was only seen in HBeAg-positive mothers with very high levels of viremia. The value of measuring HBV DNA in the pregnant woman to modify immunoprophylaxis to her infant needs further study.

Exploring the biological basis of hepatitis B e antigen in hepatitis B virus infection

The function of the hepatitis B e antigen (HBeAg) is largely unknown because it is not required for viral assembly, replication, or infection. In this report we chronicle clinical and experimental studies in an attempt to understand the role of HBeAg in natural infection. These studies largely have focused on clinical-pathologic features of HBeAg-negative variants in acute and chronic HBV infection, mutational analysis in animal models of hepadnavirus infection, and the use of transgenic murine models. The clinical and experimental data suggest that serum HBeAg may serve an immunoregulatory role in natural infection. To the contrary, cytosolic HBeAg serves as a target for the inflammatory immune response. These dual roles of the HBeAg and its ability to activate or tolerize T cells show the complexity of the interactions between the HBeAg and the host during HBV infection.

Core promoter mutations (A(1762)T and G(1764)A) and viral genotype in chronic hepatitis B and hepatocellular carcinoma in Guangxi, China

Hepatitis B viruses (HBV) with core promoter mutations (A(1762)T, G(1764)A) were found in a previous study to be highly prevalent in patients from Guangxi, China with hepatocellular carcinoma (HCC). The aim of this study was to determine whether the mutations are prevalent in areas of Guangxi with high and lower incidences of HCC and whether they are associated with other severe sequelae of chronic hepatitis B, including the development of cirrhosis. In addition, the genotypes of the various HBV sequences were determined. Core promoter mutations were significantly more common in HCC patients than asymptomatic carriers from both regions of Guangxi and also were common in patients with cirrhosis and chronic hepatitis. The data also support the hypothesis that genotype C HBV causes more severe liver disease than does genotype B.

Genomic heterogeneity of hepatitis B virus (HBV) and outcome of perinatal HBV infection

BACKGROUND/AIMS

Data regarding hepatitis B virus (HBV) genomic heterogeneity in perinatal infection are incomplete, although HBV variants might be involved in neonatal fulminant hepatitis (ALF). We investigated HBV variability in infected babies showing different clinical courses.

METHODS

We analyzed HBV genomes isolated from nine vertically infected babies and the mothers of four of them. Two infants born to HBe-antigen (HBeAg)-positive women developed a chronic infection; seven babies (six born to anti-HBe mothers) developed acute hepatitis that had a fulminant course in four cases and a benign course in three. Two babies developing ALF received anti-HBV immunoprophylaxis at birth.

RESULTS

Viruses carrying no significant mutation infected infants born to HBeAg-positive women. HBeAg-defective viruses were detected both in children with benign and fulminant hepatitis and their mothers. A double nucleotide mutation at positions 1762 and 1764 of the HBV core-promoter was found in two of the four infants with ALF, although it was not detected in isolates from the mother of one of them. No significant S gene mutation was found in HBV from any of the babies.

CONCLUSIONS

This study indicates that HBV genomic heterogeneity is not primarily involved either in the evolution of the infection or the failure of neonatal HBV immunoprophylaxis.

Risk of perinatal transmission of hepatitis B virus in Jordan

OBJECTIVES

To determine the risk of perinatal transmission of hepatitis B virus (HBV) in Jordan.

METHODS

Plasma samples from 1000 pregnant Jordanian women were screened by ELISA for HBV markers (HBsAg, HBeAg, anti-HBe, anti-HBc and anti-HBs).

RESULTS

HBsAg and HBeAg were detected in 4.3% and 0.1% of the pregnant women, respectively. The overall prevalence of antibodies was 6%, 11.1% and 7.5% for anti-HBe, anti-HBc and anti-HBs, respectively. Women were assigned to four groups according to the serological patterns of HBV markers: susceptible (85.9%), with acute infection (2.9%), with chronic infection (1.4%) and previously infected (9.8%). Most women were at the third trimester of pregnancy, therefore women with acute and chronic hepatitis at this gestational age were at risk of transmitting HBV infection to their newborns. Women who belonged to the low socio-economic class were at higher risk of HBV infection.

CONCLUSIONS

Based on the results, we recommend screening women for HBV during pregnancy in order to identify HBV carriers. All newborns born to carriers should be vaccinated immediately after birth, both passively and actively. Also vaccination of HBV seronegative pregnant women is recommended.

Natural and iatrogenic variation in hepatitis B virus

The existence of HBV as quasispecies is thought to be favoured by the infidelity of HBV RT, which would account for the emergence of the many natural mutants with point substitutions. RT infidelity may also underlie the hypermutation phenomenon. Indeed, the oft-reported point mutation in the preC gene that leads to failure of HBeAg synthesis may be driven by a hypermutation-related mechanism. The presence of mutants with deletions and insertions involving single nucleotides and oligonucleotides at specific positions in the genome, and of mutants with deletions of even longer stretches particularly in the C gene, suggests that other mutagenic mechanisms operate. Candidates include slippage during mispairing between template and progeny DNA strand, the action of cellular topoisomerase I, and gene splicing using alternative donor and acceptor sites. Natural substitutions, deletions or insertions involving the Cp/ENII locus in the X gene can significantly alter the extent of viral replicative activity. Similar mutations occurring at other locations of Cp/ENII, and at B-cell epitope sites of the S gene are associated with failure to detect serological markers of HBV infection. HBV variation can also arise from recombination between coinfecting strains. S gene mutations that become evident following HBIG administration and HBV vaccination are all point substitutions, as are mutations in functional RT domains of the P gene after treatment with viral RT-inhibitory drugs. Widespread and long-term use of prophylactic and therapeutic agents may potentially generate serologically occult HBV variants that might become difficult to eradicate.

Does hepatitis B virus (HBV) genotype influence the clinical outcome of HBV infection?

Between 5 and 10% of adults infected with the hepatitis B virus (HBV) develop a chronic infection lasting longer than 6 months, which may lead to advanced liver disease. HBV can be classified into six genotypic families: A, B, C, D, E and F, but only genotypes A and D are significantly represented in western Europe, where they account for some 90% of cases of infection with HBV. In the present study, we investigated a possible association between HBV genotype A or D and clinical outcome of the infection. We compared the prevalence of these genotypes in a group of patients with chronic active hepatitis to that of a group with acute resolving hepatitis. In patients with chronic active hepatitis, genotype A was found in 28 of 35 patients and genotype D in only four. The remaining three patients were infected with genotype non-A, non-D. In contrast, genotype D was found in 24 of 30 patients with acute hepatitis, whilst genotype A was found in only three patients of this group. Three were infected with genotype non-A, non-D. Our results show a clear association between genotype A and chronic outcome (Ficher's exact test: two-sided P-value, P < 0.0001). They suggest that HBV genotypes may play a role in the virus-host relationship. Possible mechanisms for such a role are discussed.

Human hepatitis B virus mutants: significance of molecular changes

Human hepatitis B virus, the leading pathogen for hepatitis B, is a compact DNA virus with viral genes that largely overlap. An increasing number of mutations have emerged following human interventions such as vaccination and anti-viral therapy. While vaccine escape mutants are characterized by mutations on the antigenic hepatitis B surface antigen, those carrying mutations in other viral proteins are either resistant to anti-viral therapy or implicated in acute liver diseases. Molecular identification of these various mutants should shed new lights on the underlying mechanism of hepatitis B virus viral escape and resistance and provide helpful information on their effective eradication.

Detection of different viral strains of hepatitis B virus in chronically infected children after seroconversion from HBsAg to anti-HBs indicating viral persistence

BACKGROUND/AIMS

Seroconversion to anti-HBs or the loss of HBsAg is usually associated with complete elimination of the replicative hepatitis B virus. Usually in these patients hepatitis B virus DNA (HBV DNA) becomes undetectable. Routine controls of patients who underwent anti-HBs seroconversion by more sensitive tests showed that in some cases the virus persisted in the patient. Therefore the aim of our study was to evaluate if virus persistence could also be found in children with chronic hepatitis B after anti-HBs seroconversion. The virus pool should be characterized before and after seroconversion.

METHODS

Viral DNA was extracted from nine HBsAg negative or anti-HBs positive sera of children, previously diagnosed as chronic HBsAg carriers. HBV DNA was amplified by polymerase chain reaction. Subsequently the nucleotide sequences of the polymerase chain reaction product in the a-determinant region (aa 121-161) were analyzed on an automatic fluorescent sequencer.

RESULTS

In the sera of seven children, HBV DNA was detected in the HBsAg negative phase of the HBV infection. Mutations in codons 122, 125, 127, 131, 134, 143, 159 and 161 of the S gene could be documented, resulting in amino acid changes. In three patients the sequence analysis revealed changes in the HBV genotype from genotype A (serotype adw) to genotype D (serotype ayw) during seroconversion to anti-HBs.

CONCLUSIONS

These data demonstrate that persistence of the hepatitis B virus can also occur in HBsAg negative and anti-HBs positive children. After loss of HBsAg, no specific HBV variant was identified. Although a conclusive explanation for the selection process cannot be provided, it remains a fact that the 'surviving' viral strain was mostly represented by genotype D.