Expression of defective hepatitis B virus particles derived from singly spliced RNA is related to liver disease.

BACKGROUND: Defective hepatitis B virus (HBV) particles, generated from singly spliced HBV RNA, have been detected in chronic carriers of HBV. The present study was designed to quantify the expression of defective HBV (dHBV) and wild-type HBV (wtHBV) genomes in the serum of patients with HBV infection and its relation to the severity of liver disease. METHODS: HBV and dHBV loads were determined by quantitative polymerase chain reaction in the serum of 89 untreated HBV-infected patients (31 coinfected with human immunodeficiency virus [HIV] type 1) with liver disease of different stages. The ratio of dHBV DNA to total (wtHBV plus dHBV) HBV DNA (dHBV/HBV ratio) was used to express data independently of the level of viral replication. RESULTS: Despite a global correlation between dHBV and wtHBV load, the dHBV/HBV ratio ranged from 0.001% to 69%. The variation in dHBV/HBV ratio was independent of HIV coinfection, HBV genotype, and precore mutations. The mean dHBV/HBV ratio was higher in patients with severe liver necrosis and fibrosis. CONCLUSIONS: Our data indicate that an elevated dHBV/HBV ratio is associated with liver necroinflammation and fibrosis disease, suggesting a regulation of dHBV expression according to the severity of the liver disease. The dHBV/HBV ratio may help to better define liver disease stage during HBV infection.

Human MxA protein participates to the interferon-related inhibition of hepatitis B virus replication in female transgenic mice.

BACKGROUND/AIMS: The interferon (IFN) inducible MxA protein is endowed with antiviral activity against a broad range of RNA viruses. In a previous in vitro study, we demonstrated that MxA inhibits hepatitis B virus (HBV) replication, arguing that the antiviral activity of MxA is not restricted to RNA viruses but also includes a DNA virus. The aim of the present study was to further demonstrate in vivo the antiviral action of MxA against HBV. METHODS: We generated HBV and HBV/MxA transgenic mice lacking a functional IFN-alpha/beta receptor and thus constituting a good model to evaluate MxA-induced virus resistance. HBV proteins expression, viral load and HBV replication were compared in HBV and HBV/MxA mice. RESULTS: An MxA-dependent moderate inhibitory effect on HBV expression was only observed in female HBV/MxA mice, in which MxA downregulates (i) viral HBeAg and capsid protein expression, (ii) viremia and (iii) HBV replication by decreasing the synthesis of HBV DNA replicative intermediates. Furthermore, these effects were not associated with changes to steady-state levels of HBV RNAs. CONCLUSIONS: Our results show that in vivo, MxA is able per se to reduce HBV expression by a post-transcriptional mechanism, and thus participates in the antiviral activity of IFN-alpha against HBV.

The expression of hepatitis B spliced protein (HBSP) encoded by a spliced hepatitis B virus RNA is associated with viral replication and liver fibrosis.

BACKGROUND/AIMS: We have previously demonstrated the in vivo expression of a new spliced hepatitis B virus (HBV) protein (HBSP) encoded by a singly spliced pregenomic RNA. The present study was designed to evaluate the impact of HBSP expression on the clinical status and liver pathology of HBV infection. METHODS: Sera from 125 chronic HBV carriers were tested for the presence of HBSP antibodies by an indirect enzyme-linked immunosorbent assay test. The severity of liver damage was evaluated using the Knodell score. RESULTS: Anti-HBSP antibody prevalence in HBV chronic carriers was 46%. We highlighted the concomitant expression of HBSP protein and anti-HBSP antibody. An association between anti-HBSP antibody detection and serum markers of HBV replication was demonstrated. With respect to HBV-related liver disease, an association was only observed with the severity of fibrosis. Furthermore, an elevation of secreted tumor necrosis factor alpha (TNFalpha), but not of soluble TNFalpha receptor 75, was observed in anti-HBSP-antibody-positive patients. Multivariate analysis showed that anti-HBSP antibody detection was independently associated with viral replication, severity of fibrosis and elevated TNFalpha secretion. CONCLUSIONS: Our data suggest the hypothesis that HBSP might play a role in the natural history of HBV infection and may be involved in the pathogenesis and/or persistence of HBV infection.

Vaccination of chronic hepatitis B virus carriers with preS2/S envelope protein is not associated with the emergence of envelope escape mutants.

PreS2/S vaccination of chronic hepatitis B virus (HBV) carriers led to a reduction in HBV replication or clearance of virus in 30% of treated patients. This study assessed whether vaccinotherapy of chronic HBV carriers induced the selection of escape mutants in the envelope 'a' determinant and whether envelope genetic variability might affect the response to vaccination. No amino acid differences were observed in the 'a' determinant between sequences obtained before and after treatment (five responders and seven non-responders). However, alignment with HBV prototype sequences revealed seven amino acid changes. Two mutations (T140S and P127L) diverged from subtype variations. In the complete envelope sequence (five non-responders and five responders), ten amino acid modifications were detected between sequences obtained before and after treatment. The absence of any common mutations did not enable the definition of a hot spot of mutations implicated in the response to vaccination. Moreover, vaccinotherapy does not induce the selection of escape mutants in the 'a' determinant.