Antibodies in anti-HBe-positive patient sera bind to an HBe protein expressed on the cell surface of human hepatoma cells: implications for virus clearance

The relevance of the recently described membrane-bound form of the HBe protein for the antiviral immune response was examined. The data show that antibodies in anti-HBe, but not in anti-HBc-positive human sera efficiently bind to the membrane expressed HBe. No evidence was obtained that the HBc can reach the cell surface in a form that can be detected with human antibodies. The findings suggest that the decline of virus titer that is usually observed after seroconversion from HBe to anti-HBe might be the result of an antibody-mediated elimination of infected cells.

Hepatitis B virus propagated in a rat hepatoma cell line is infectious in a primate model

The human hepatitis B virus (HBV) produced by a rat hepatoma cell line through transfection with HBV DNA is infectious in the human primate model--chimpanzee. Since hepadnaviruses are known to have an extremely narrow host range, our results support the idea that the host species barrier of HBV infection resides on the penetration/adsorption step rather than any postpenetration intracellular event during the virus life cycle.

Latency and reactivation of a precore mutant hepatitis B virus in a chronically infected patient

In human patients infected with hepatitis B virus (HBV) seroconversion from HBe to anti-HBe often signals virus elimination. Occasionally, a second viremic phase is observed which may be due to superinfection with a variant or reactivation of a latent virus. To differentiate between these two possibilities we investigated the nucleotide sequences of virus populations from sera of a chronically infected patient who had two distinct viremic phases, one e-antigen positive and one anti-HBe antibody positive. By direct sequencing of amplified HBV C- and pre-S gene sequences we found that the viruses in the two populations differed by only two point mutations, one of which prevents expression of precore derived e-antigen. In the nonviremic phase viral DNA and antigen were found in the liver but nucleocapsid protein expression appeared drastically downregulated. These data demonstrate that HBV can enter a latent phase with low expression of core protein and selection for HBV variants which cannot synthesize e-antigen. This suggests that e-antigen expression can be a critical target for virus elimination and that loss of its expression can prolong chronicity and provoke latency of HBV infection.

[Clinical and histological observation of HBV glomerulonephritis treated with interferon-beta]

Hepatitis B virus carriers, a 30-year-old man (case 1) and a 31-year-old man (case 2), associated with nephrotic syndrome were treated with interferon-beta. The nephrotic syndrome did not respond to corticosteroid therapy. Their HBs-Ag, HBe-Ag and HBc-Ab were positive. Renal biopsies revealed membranous glomerulonephritis in case 1 and mixed membranous and proliferative glomerulonephritis in case 2. Direct immunofluorescence studies showed strong granular staining of the GBM with IgG and using sandwich technique with anti-HBe antiserum, granular deposits were seen throughout the GBM. Patients were administrated mainly 3-6 x 10(6) IU/day interferon-beta intravenously for four weeks. After transitory elevation of serum transaminase, HBe-Ag and DNA-polymerase have disappeared with development of HBe-Ab (seroconversion) about six months after the end of interferon-beta administration. Then nephrotic syndrome has recovered in incomplete remission after a year and a half follow-up. The secondary renal biopsy in case 1 showed less intense deposits of HBe-Ag along GBM. These facts suggest that the improvement of proteinuria is associated with the decrease in HBV replication due to interferon therapy.

[Activation of the interferon system enzymes by recombinant alpha2-interferon in patients with chronic hepatitis B]

Treatment of patients suffering from chronic hepatitis B with recombinant leukocytic interferon (reaferon) increased the levels of circulating interferon and activated interferon-dependent enzymes such as 2-5A-synthetase and histone kinase. Activation of the enzymes was observed for 1 to 2 weeks. After that period it was maintained at the required levels with intramuscular administration of 1-3 million units of reaferon 2 or 3 times a week. In parallel with increasing of the levels of the interferon system enzymes there was observed a decrease in the level of aminotransferase. The reaction of the viral antigens to the treatment with reaferon was not the same: HBe antigen and antibodies to HBe antigen disappeared, the content of HBs antigen and antibodies to delta-interferon did not change.

Immunoelectron microscopic localization of membrane attack complex and hepatitis B e antigen in membranous nephropathy

Immunoelectron microscopy was used to localize membrane attack complex (MAC) and hepatitis B e (HBe) antigen in renal tissue specimens from a total of 9 patients with membranous nephropathy (MN); 6 with MN associated with a hepatitis B virus (HBV) infection, 2 with idiopathic MN, and 1 with lupus nephritis. All the patients were proteinuric, and 2 patients were classified as stage I-II, 6 as stage II, and 1 as stage IV. MAC, along with IgG and C3, was distributed within the subepithelial electron dense deposits in all the stages. MAC was also stained in the striated membranous structures within the glomerular basement membrane and mesangial matrix of some patients. In HBV-associated MN, HBe antigen was localized in the subepithelial electron dense deposits of 5 patients, while it was absent from the subepithelial deposits in a patient that was sero-positive for hepatitis B s antigen but negative for HBe antigen. This patient also lacked MAC deposition in these loci. These results suggest that MAC is associated with the formation of subepithelial deposits and proteinuria in MN. In HBV-associated MN, HBe antigen-antibody immune complex makes up the subepithelial deposits and is likely to activate the terminal components of complement in situ.

Influence of hepatitis delta virus superinfection on the clearance of hepatitis B virus (HBV) markers in HBV carriers in Japan

To elucidate the influence of hepatitis delta virus (HDV) superinfection on the clearance of hepatitis B virus (HBV) associated antigens in HBV carriers, we examined for antibody to hepatitis delta antigen (anti-HD) serial sera collected from 1,029 HBV carriers in Kure, Japan. Of the 242 HBV carriers with hepatitis B e antigen (HBeAg), 28 became seropositive for anti-HD, of whom 18 (64.3%) cleared HBeAg; 214 did not become seropositive for anti-HD, of whom 70 (32.7%) cleared HBeAg. Thus, HBeAg clearance was observed in a significantly higher proportion of HDV-superinfected carriers as compared with carriers without HDV infection (P less than 0.005). In the 56 HBV carriers who cleared hepatitis B surface antigen (HBsAg), anti-HD was detected in three cases with increased serum alanine aminotransferase activity preceding HBsAg clearance. The duration of anti-HD seropositive state was less than 5 years, and the titer of anti-HD was relatively low in every case. These data suggest that the HDV infection rate in Japan is higher than previously reported, that HDV superinfection can be one of the factors that induce the HBeAg clearance and HBsAg clearance in HBV carriers, and also that the most likely outcome of HDV superinfection in HBV carriers in Japan may be acute self-limited infection.

Relation between HBsAg binding with polymerized human serum albumin and HBV replication

The binding between hepatitis B surface antigen (HBsAg) and polymerized human serum albumin (poly-HSA) was studied in HBsAg-negative (25) and HBsAg-positive (92) sera by a sensitive enzyme-linked immunosorbent assay technique, and a correlation of binding activity was made with HBe-markers and hepatitis B virus-specific DNA polymerase. The binding could be detected only in HBsAg-positive sera and was found to be independent of the presence of HBe-markers and DNA polymerase activity. Further, binding was noted in significantly higher proportions of sera samples from the patient group compared with the healthy carrier group (p less than 0.01).

Hepatitis B virus gene function: the precore region targets the core antigen to cellular membranes and causes the secretion of the e antigen

The core gene of the hepatitis B virus genome contains two conserved in-phase initiation codons separated by about 90 nucleotides. This region ("the precore region") encodes largely hydrophobic amino acids. We have expressed the coding sequence of the core gene with or without the precore region by using a simian virus 40-derived vector in heterologous mammalian cells. The results show that the precore region is not required for the expression either of core antigen (cAg) or of a related hepatitis B virus antigen, the e antigen (eAg). However, the precore region causes the cAg to become associated with cytoplasmic membranes, probably the endoplasmic reticulum. Further, the presence of the precore sequence results in the secretion of eAg. Our results suggest that the precore region plays a role in targeting core proteins to the membrane; this may be the direct cause of eAg secretion and also may aid in the interaction of the core and surface antigens in the formation of the viral particle.

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Background

Chronic hepatitis B (CHB) is a dynamic disease that may be affected by immune changes in pregnancy. Guidelines suggest consideration of nucleos/tide analogs (NA), i.e., tenofovir, (TDF) in highly viremic mothers to reduce vertical transmission risk. HBV variability affects CHB outcome, but little is known about HBV genetic changes in pregnancy due to immune or NA selection.

Objectives

To evaluate HBV diversity in NA treated or untreated pregnant vs. post-partum CHB carriers.

Study Design

In plasma collected from 21 mothers (7 matching pre/post-partum), HBV serological tests, genotype and viral load were assayed. The HBV pre-surface (S) /S overlapping polymerase (P) (N = 20), pre-core (C) /C (N = 11) and/or full genome PCR amplicons (N = 3) underwent clonal sequence analysis.

Results

The median age was 31 y, 71% Asian, 68% genotype B or C, 33% HBV eAg+, 5 received TDF (median HBV DNA 8.5 log IU/ml). In untreated mothers, median antepartum vs. post-partum ALT was 21 vs. 24 U/L and HBV DNA was 2.7 vs. 2.4 log(10) IU/ml. ALT and/or HBV DNA flares occurred during pregnant and/or post-partum period in 47% (10/21). Clonal sequencing antepartum showed the presence of minor “a determinant” and/or vaccine escape mutants (VEM) but drug resistant variants were infrequent. Analysis of pregnant vs. post-partum samples showed different HBV variants and viral diversity.

Conclusions

Differences in immune and/or by NA selective pressures during pregnancy may affect HBV evolution during pregnancy. The presence of minor VEM warrant infant follow-up.