Search results for "digestive system"

Assay of hepatitis B virus DNA by polymerase chain reaction and its relationship to Pre-S- and S-encoded viral surface antigens

1991

The polymerase chain reaction was evaluated as a diagnostic tool in 72 chronic hepatitis B virus carriers. Hepatitis B virus DNA was detectable in the serum of HBsAg—positive virus carriers using aliquots as small as 100 al. The detection limit for cloned hepatitis B virus DNA was 100 ag. Primer pairs for different regions of the HBV genome resulted in different sensitivity. Detection of the amplified hepatitis B virus DNA by Southern blotting and subsequent scintillation counting or densitometry allowed a semiquantitative assay. Using several primer pairs in parallel for optimal detection, all HBeAg-positive HBsAg carriers, 80% of HBe antibody—positive symptomatic HBsAg carriers and 57% of…

Mosaic hepatitis B virus core particles presenting the complete preS sequence of the viral envelope on their surface

2004

The sequence of the preS domain of the hepatitis B virus (HBV, genotype D) envelope was inserted into the major immunodominant region (MIR) of the C-terminally truncated HBV core (HBc) protein. In Escherichia coli, the HBc–preS fusion protein was partially soluble and did not produce particles. Co-expression of the wild-type HBc as a helper protein along with the fusion protein led to the formation of mosaic HBc particles that exhibited HBc, preS1 and preS2 antigenicity. Two alternative combinations of medium- and high-copy plasmids were used for co-expression of fusion and helper proteins, in an attempt to improve mosaic particle production. However, the preS fusion content of the particle…

Hepatitis B protein HBx binds the DLEU2 lncRNA to sustain cccDNA and host cancer-related gene transcription.

2019

Objective: The HBV HBx regulatory protein is required for transcription from the covalently closed circular DNA (cccDNA) minichromosome and affects the epigenetic control of both viral and host cellular chromatin. Design: We explored, in relevant cellular models of HBV replication, the functional consequences of HBx interaction with DLEU2, a long non-coding RNA (lncRNA) expressed in the liver and increased in human hepatocellular carcinoma (HCC), in the regulation of host target genes and the HBV cccDNA. Results: We show that HBx binds the promoter region, enhances the transcription and induces the accumulation of DLEU2 in infected hepatocytes. We found that nuclear DLEU2 directly binds HBx…

Overexpression of STAT-1 by adenoviral gene transfer does not inhibit hepatitis B virus replication.

2006

Objectives Interferons are known to inhibit the replication of hepatitis B viruses (HBV) in several animal models in vitro and in vivo as well in humans. The STAT-1 protein plays a central role in the biological activity of both type I and type II interferons. The lack of functional STAT-1 renders cells and organisms susceptible to bacterial and viral infectious agents. We analysed whether the overexpression of STAT-1 protein enhances the biological interferon response and whether it elicits antiviral acitivity against HBV in vitro. Methods To achieve an efficient STAT-1 overexpression in primary liver cells and hepatoma cells, we generated a recombinant, replication-deficient adenovirus ex…

Recent progress and new trends in the treatment of hepatitis B

2002

The annual rate of progression to cirrhosis in patients with chronic HBV is 0.4 to 14.2% and that of death 4 to 10%. HCC risk increases in parallel with the severity and duration of infection, with an annual incidence less than 0.5% in carriers and 6% in patients with cirrhosis. The main aim of antiviral therapy for chronic "wild-type" HBV infection is to suppress viral replication before cirrhosis and HCC develop. Two drugs are approved: IFN alpha and lamivudine. IFN alpha is costly, has a narrow range of efficacy, safety, and tolerability. Lamivudine is active, cheaper, and better tolerated but has limited efficacy, being associated with increasing resistance and loss of clinical response…

Global stability analysis of a delay cell-population model of hepatitis B infection with humoral immune response

2021

In this work, we propose and investigate a delay cell population model of hepatitis B virus (HBV) infection. We suppose spatial diffusion of free HBV particles, and use a Beddington-DeAngelis incid...

Hepatitis B core particles as a universal display model: a structure-function basis for development

1999

AbstractBecause it exhibits a remarkable capability to accept mutational intervention and undergo correct folding and self-assembly in all viable prokaryotic and eukaryotic expression systems, hepatitis B core (HBc) protein has been favored over other proposed particulate carriers. Structurally, the unusual α-helical organization of HBc dimeric units allows introduction of foreign peptide sequences into several areas of HBc shells, including their most protruding spikes. Progress toward full resolution of the spatial structure as well as accumulation of chimeric HBc-based structures has brought closer the knowledge-based design of future vaccines, gene therapy tools and other artificial par…

2015

Objective The Hepatitis B virus genome persists in the nucleus of virus infected hepatocytes where it serves as template for viral mRNA synthesis. Epigenetic modifications, including methylation of the CpG islands contribute to the regulation of viral gene expression. The present study investigates the effects of spontaneous age dependent loss of hepatitis B surface protein- (HBs) expression due to HBV-genome specific methylation as well as its proximate positive effects in HBs transgenic mice. Methods Liver and serum of HBs transgenic mice aged 5–33 weeks were analyzed by Western blot, immunohistochemistry, serum analysis, PCR, and qRT-PCR. Results From the third month of age hepatic loss …

Mixed cryoglobulinemia type II in chronic hepatitis B associated with HBe-minus HBV mutant: Cellular immune reactions and response to interferon trea…

1994

The case of a young female patient with chronic active hepatitis B, vasculitic purpura, edema, and circulating immune complexes due to mixed Cryoglobulinemia is described. Serum transami-nases were elevated. Serological assays showed hepatitis B surface antigen (HBsAg), antibody to hepatitis B e antigen (anti-HBe), and antibody to hepatitis B core antigen (anti-HBc) antibodies but no antibody to hepatitis C virus (anti-HCV) or antibody to hepatitis delta virus (anti-HDV) antibodies. Using hepatitis B virus-polymerase chain reaction (HBV-PCR) and direct sequencing a precore/core (preC/C) mutant unable to synthesize HBeAg was detected in serum. HBV antigens were demonstrated in the circulatin…

Cellular and humoral immune responses induced by intradermal or intramuscular vaccination with the major hepatitis B surface antigen

2000

The vaccination route may influence the success of immunization against pathogens. The conventional intramuscular (i.m.) application of a vaccine containing the hepatitis B virus (HBV) surface antigen (HBsAg) led to protective anti-HBs antibody levels in the majority of vaccine recipients. In this study, we vaccinated healthy volunteers and a group of i.m. vaccine nonresponders via the intradermal (i.d.) route and analyzed the HBV-specific B-cell response as well as class-II- and class-I-restricted T-cell responses by 3 H-thymidine uptake, enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunospot assay (ELISPOT). The results were then compared with i.m. vaccinated controls. I.d…