Prognostic importance of antigen-presenting dendritic cells during vaccine therapy in a murine hepatitis B virus carrier.
(17/4254)
As, the outcome of vaccine therapy was extremely heterogeneous in both human and murine hepatitis B virus (HBV)-carriers, the experiments presented here were performed to find out a prognostic marker of vaccine therapy using an animal model of HBV-carrier state, HBV-transgenic mice (Tg). Neither the prevaccinated titres of viral markers, such as hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) or HBV DNA, nor the function of lymphocytes prior to vaccination, had significant influence on the outcome of vaccine therapy. Two independent, placebo-controlled, trials of vaccine therapy for 12 months, one in 17 HBV-Tg and the other in 26 HBV-Tg (total, n=43) showed that the eight of 17 and 15 of 26 HBV-Tg that had potent dendritic cell (DC) function at the start of vaccine therapy became completely negative for HBsAg, HBeAg and reduced HBV DNA, whereas all 19 HBV-Tg that had poor DC function at the start of vaccine therapy became complete non-responders, although, the prevaccinated titres of HBsAg, and HBeAg were similar in all 43 HBV-Tg. Further study to find the mechanism underlying this revealed that there was up-regulation of major histocompatibility complex (MHC) class II, CD86 antigens on DC and increased production of interleukin-12 (IL-12) by DC and of IL-2, and tumour necrosis factor-alpha (TNF-alpha) in DC/T-cell cultures when vaccine containing HBsAg was injected in HBV-Tg with potent DC function but not in HBV-Tg with poor DC function. This is the first report on the prognostic importance of DC during an immune therapy. Degree of activation of DC following vaccination would possibly help to predict the outcome of vaccine therapy in human HBV-carriers. These data also provide the scientific and logical basis to up-regulate the function of the DC before an immune therapy. (+info)
Effect of multiple freeze-thaw cycles on hepatitis B virus DNA and hepatitis C virus RNA quantification as measured with branched-DNA technology.
(18/4254)
Quantification of hepatitis B virus (HBV) DNA and hepatitis C virus (HCV) RNA often is performed in specimens that have been frozen and thawed more than once. To ensure optimal therapeutic and prognostic value, it is important to establish whether viral load measurements are affected by repeated freeze-thaw (FT) cycles. We therefore evaluated the effect of multiple FT cycles on HBV DNA and HCV RNA quantification by testing serum specimens subjected to one (baseline), two, four, and eight FT cycles with the appropriate Chiron Quantiplex assay. Linear regression analysis showed minor increases of 1.7% per FT cycle for both HBV DNA and HCV RNA. The rise in HCV RNA levels was more pronounced among low-concentration samples, since further analysis revealed an increase of 3.2% per FT cycle among samples with 0.2 to 3.86 Meq of HCV RNA per ml. Given that the coefficient of variation for the Quantiplex assays is generally 10 to 15%, the minor increases in HBV DNA and HCV RNA levels with progressive FT cycles for the specimens tested were recognized only because analysis of variance revealed a statistically significant trend (P < 0.05). Due to the minor statistical trend, the clinical impact for individual patient specimens is likely to be limited, but it may deserve further study. In conclusion, the concentration of HBV DNA and HCV RNA in serum specimens subjected to up to eight short-term FT cycles was stable. (+info)
Infections associated with medical intervention: hepatitis viruses and HGV.
(19/4254)
Transfusion and other medical interventions, as well as their non-medical derivatives, have a lot to answer for. Much of HCV infection can be traced back to this route, HGV is still being transmitted in this way and a substantial proportion of HBV in Africa has been spread around by use of contaminated skin-piercing manoeuvres, medical or otherwise. Many practitioners can still remember the days when blood-borne viruses were not a major feature of medical curricula. Unfortunately, patients currently subjected to cost-cutting medical practices, for example use of unscreened blood and re-use of needles, will have to pay the price in years to come. The evolution of these viruses is linked to their route of introduction, but the relationship between variability and clinical outcome is less certain. Nevertheless, variability is important for clinical practice, especially for the design of sensitive diagnostics and highly effective vaccines. (+info)
Quantitative analysis of hepatitis B virus precore mutant in hepatitis type B.
(20/4254)
Active liver disease has been detected in chronic hepatitis B after seroconversion from positive HBe antigen to positive anti-HBe antibody. Active replication of HB virus (HBV) containing a precore stop-codon mutation has been implicated in this condition. The usual methods, such as direct sequencing, to characterize the responsible mutant of HBV are not suitable for routine clinical use. Here we employed the competitive mutation site specific assay (CMSSA) to detect precore mutant HBV-DNA in patients with positive HB surface antigen. In patients with HBe antigen, precore mutant HBV-DNA was significantly higher than in patients with HBe antibody. The level of precore mutant HBV-DNA in patients with elevated serum ALT was significantly higher than in patients with normal serum ALT. Sex, age and the level of serum HBV-associated DNA polymerase levels were not correlated with levels of precore mutant HBV-DNA. Ten of 11 negative patients for the precore mutant by polymerase chain reaction followed by restriction fragment length polymorphism assay (PCRRFLP) were positive for the precore mutant by CMSSA. These results suggest that the precore mutant has already emerged in the HBeAg-positive phase as determined by CMSSA, which is more sensitive than PCR-RFLP and is useful for evaluating the clinical course of patients with chronic hepatitis B. (+info)
Hepatitis B virus genotype assignment using restriction fragment length polymorphism patterns.
(21/4254)
Hepatitis B virus (HBV) is classified into genotypes A-F, which is important for clinical and etiological investigations. To establish a simple genotyping method, 68 full-genomic sequences and 106 S gene sequences were analyzed by the molecular evolutionary method. HBV genotyping with the S gene sequence is consistent with genetic analysis using the full-genomic sequence. After alignment of the S sequences, genotype specific regions are identified and digested by the restriction enzymes, HphI, NciI, AlwI, EarI, and NlaIV. This HBV genotyping system using restriction fragment length polymorphism (RFLP) was confirmed to be correct when the PCR products of the S gene in 23 isolates collected from various countries were digested with this method. A restriction site for EarI in genotype B was absent in spite of its presence in all the other genotypes and genotype C has no restriction site for AlwI. Only genotype E is digested with NciI, while only genotype F has a restriction site for HphI. Genotype A can be distinguished by a single restriction enzyme site for NlaIV, while genotype D digestion with this enzyme results in two products that migrates at 265 and 186 bp. This simple and accurate HBV genotyping system using RFLP is considered to be useful for research on HBV. (+info)
HBV and proteinuria in relatives and contacts of children with hepatitis B virus-associated membranous nephropathy.
(22/4254)
BACKGROUND: Hepatitis B virus (HBV)-associated membranous nephropathy (HBVMN) is an important cause of childhood nephrotic syndrome in regions endemic for the virus, but little is understood of the biosocial context in which the disease develops. We evaluated HBV status and proteinuria in family members and household contacts of index children with HBVMN to test the hypothesis that HBV carriage and asymptomatic proteinuria are closely linked and may be causally associated. METHODS: Thirty-one black children with biopsy-proven HBVMN were the index cases. One hundred and fifty-two family members and 43 black household contacts were the subjects of the study. We assessed HBV carrier status by testing for HBV antigens and antibodies using enzyme-linked immunosorbent assays (ELISA) and for HBV DNA by using slot-blot hybridization and the polymerase chain reaction. Sequencing of the precore region of HBV was done in a subset of both index cases and subjects. Proteinuria was assessed by measuring the urinary protein/creatinine ratio. RESULTS: Seventy-two (37%) of the 195 family members and household contacts were HBV carriers, and 53 (27%) had a protein/creatinine ratio greater than the physiological limit. The frequency of abnormal proteinuria was not significantly different in those with [22 out of 72 (30.5%)] or without [33 out of 104 (32%)] HBV carriage. This lack of association remained when carriers were classified into those who were HBsAg positive only and those with active viral replication (HBsAg and/or HBeAg and/or HBV DNA; P = 0.01). Family members were more predisposed to HBV carriage than household contacts, but abnormal proteinuria was present with equal frequency (P = 0.48). Age had a significant impact on proteinuria, with children less than five years being more likely to have abnormal proteinuria (P = 0.008). The prevalence of abnormal proteinuria in family members and household contacts of the index cases was more than that in community-based controls. The 10 index HBVMN cases and the 14 family members and household contacts who were tested all had HBV of genotype A. CONCLUSION: These results suggest that the family members and household contacts of children with HBVMN are at very high risk of HBV carriage; they also have asymptomatic proteinuria at a significantly higher rate than community-based controls. The HBV carrier status was not associated with proteinuria, a finding supported by peak prevalences of proteinuria in those under five years but no corresponding peak for HBV carriage. Proteinuria may indicate glomerular basement membrane dysfunction. Environmental and social factors may underpin development of these two covert disorders, but are insufficient to account for the index cases of HBVMN. The emergence of children with HBVMN from such households additionally depends on unidentified and possibly genetic factors. (+info)
Inhibition of interferon-inducible MxA protein expression by hepatitis B virus capsid protein.
(23/4254)
Chronic hepatitis B treatment has been significantly improved by interferon (IFN) treatment. However, some studies have suggested that hepatitis B virus (HBV) might have a direct effect on the resistance to IFN. Defective particles, generated by spliced HBV RNA and associated with chronic hepatitis B, have been previously characterized; expression of these particles leads to cytoplasmic accumulation of the capsid protein. The aim of this study was to investigate the role of these defective genomes in IFN resistance. The global antiviral activity of IFN was studied by virus yield reduction assays, the expression of three IFN-induced antiviral proteins was analysed by Western blotting and confocal microscopy, and the regulation of MxA gene expression was studied by Northern blotting and the luciferase assay, in Huh7 cells transfected with a complete or the defective HBV genome. Results showed that the expression of the defective genome reduces the antiviral activity of IFN and that this modulation involves a selective inhibition of MxA protein induction by the HBV capsid protein. Our results also show the trans-suppressive effect of the HBV capsid on the MxA promoter, which might participate in this phenomenon. In conclusion, this study shows a direct interplay between the IFN-sensitive pathway and the capsid protein and might implicate this defective HBV genome in virus persistence. (+info)
Combinatorial screening and intracellular antiviral activity of hairpin ribozymes directed against hepatitis B virus.
(24/4254)
A combinatorial screening method has been used to identify hairpin ribozymes that inhibit hepatitis B virus (HBV) replication in transfected human hepatocellular carcinoma (HCC) cells. A hairpin ribozyme library (5 x 10(5) variants) containing a randomized substrate-binding domain was used to identify accessible target sites within 3.3 kb of full-length in vitro-transcribed HBV pregenomic RNA. Forty potential target sites were found within the HBV pregenomic RNA, and 17 sites conserved in all four subtypes of HBV were chosen for intracellular inhibition experiments. Polymerase II and III promoter expression constructs for corresponding hairpin ribozymes were generated and cotransfected into HCC cells together with a replication-competent dimer of HBV DNA. Four ribozymes inhibited HBV replication by 80, 69, 66, and 49%, respectively, while catalytically inactive mutant forms of these ribozymes affected HBV replication by 36, 28, 0, and 0%. These findings indicate that the inhibitory effects on HBV replication were largely mediated by the catalytic activity of the ribozymes. In conclusion, we have identified catalytically active RNAs by combinatorial screening that mediate intracellular antiviral effects on HBV. (+info)