Search results for "Replication"
showing 10 items of 489 documents
Klinische Bedeutung des Hepatitis-B-Virus-DNS-Nachweises im Serum von Kindern mit chronischer Hepatitis B
1992
206 sera from 172 children with chronic hepatitis B infection were tested for HBV DNA by dot blot hybridization. 111 were positive and 95 negative for HBV DNA. 103 (78.6%) of the positive patients had HBeAg and 5 (7.7%) anti-HBe. In 60 (92.3%) of the anti-HBe positive sera no HBV DNA could be detected. Children with elevated liver enzymes had HBV DNA in 80.1%, whereas in 71.6% of the chronic HBsAg carriers with normal liver enzymes no HBV DNA was found. In 87 of the 95 dot blot negative patients polymerase chain reaction was performed. 73 (83.9%) children of this group were HBV DNA positive. All HBeAg positive patients and those with elevated aminotransferases had HBV DNA in their serum. 56…
Translation of hepatitis B virus (HBV) surface proteins from the HBV pregenome and precore RNAs in Semliki Forest virus-driven expression.
2004
Hepatitis B virus (HBV) pregenome RNA (pgRNA) serves as a translation template for the HBV core (HBc) protein and viral polymerase (Pol). HBV precore RNA (pcRNA) directs the synthesis of the precore (preC) protein, a precursor of the hepatitis B e antigen (HBeAg). pgRNA and pcRNA were expressed in the Semliki Forest virus (SFV) expression system. Besides the HBc and preC proteins, there was revealed the synthesis of all three forms of HBV surface (HBs) proteins: long (LHBs), middle (MHBs) and short (SHBs), the start codons of which are located more than 1000 nt downstream of the HBc and preC start codons. Moreover, other HBV templates, such as 3′-truncated pgRNA lacking 3′ direct repeat and…
Polyalbumin receptors, hepatitis B surface antigen (HBsAg), and HBsAg/IgM complexes in HBsAg positive patients with and without delta superinfection.
1985
Receptors for polymerized human albumin are found at high litres during high-level hepatitis B virus (HBV) replication and in small amounts in chronic low-level infection. Complexes between hepatitis B surface antigen (HBsAg) and IgM without specificity for HbsAg are expressed in a pattern similar to that of receptors. Anti-albumin antibodies could be involved in their formation. Delta infection depresses the synthesis of gene products of HBV. To assess whether delta modifies the expression of receptors on HBsAg and the level of HBsAg/IgM complexes, and if anti-albumin antibodies are actually part of the complex, we tested sera from 86 subjects with acute and chronic HBV infection. Our find…
Mutations in DNA Binding and Transactivation Domains Affect the Dynamics of Parvovirus NS1 Protein
2013
ABSTRACT The multifunctional replication protein of autonomous parvoviruses, NS1, is vital for viral genome replication and for the control of viral protein production. Two DNA-interacting domains of NS1, the N-terminal and helicase domains, are necessary for these functions. In addition, the N and C termini of NS1 are required for activation of viral promoter P38. By comparison with the structural and biochemical data from other parvoviruses, we identified potential DNA-interacting amino acid residues from canine parvovirus NS1. The role of the identified amino acids in NS1 binding dynamics was studied by mutagenesis, fluorescence recovery after photobleaching, and computer simulations. Mu…
Immune activation promotes evolutionary conservation of T-cell epitopes in HIV-1.
2013
The immune system should constitute a strong selective pressure promoting viral genetic diversity and evolution. However, HIV shows lower sequence variability at T-cell epitopes than elsewhere in the genome, in contrast with other human RNA viruses. Here, we propose that epitope conservation is a consequence of the particular interactions established between HIV and the immune system. On one hand, epitope recognition triggers an anti-HIV response mediated by cytotoxic T-lymphocytes (CTLs), but on the other hand, activation of CD4(+) helper T lymphocytes (TH cells) promotes HIV replication. Mathematical modeling of these opposite selective forces revealed that selection at the intrapatient l…
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…
Chronic hepatitis B: Do we know everything or is there still something to learn?
2009
Chronic hepatitis B is a dynamic process with different phases. The progression of liver damage is related to time of infection, linked to the persistence of viral replication, and based on the virus–host interaction. [1]. The course of liver disease can be modified by virological events related to the kinetics of HBV replication and influenced by the host immune system. Knowledge of the natural history of HBV infection and of its viral replication mechanisms suggest the treatment end points and guide the choice of antiviral drugs [2–4]. The key points for the management of chronic hepatitis Ba re: Evaluation of viral status (HBeAg positive or HBeAg negative), staging of liver disease (chro…
Virus replication and virion export in X-deficient hepatitis B virus transgenic mice
2002
The function of the X protein (pX) in the replication cycle of mammalian hepadnaviruses is enigmatic. Using tissue culture experiments it has been shown that the X gene product is not central to hepatitis B virus (HBV) replication and virion export. However, at present it is still unclear whether this also applies to the in vivo situation. Using a terminally redundant X-deficient HBV DNA construct, transgenic mice were established that exhibited high-level expression of the viral core protein in liver and kidneys. Importantly, replicative DNA intermediates and mature viral genomes could be detected in the liver and serum of these mice, respectively. These findings indicate that, in the in v…
Molecular hybridization techniques in current diagnosis of chronic hepatitis B in childhood.
1992
Following the cloning and sequencing of the hepatitis B virus genome, molecular hybridization techniques have been established to detect hepatitis B virus (HBV) DNA in serum and liver tissue. Analyses can be performed by dot blot, Southern blot and in situ hybridization. HBV DNA is regarded to be the most sensitive marker of viral replication and infectivity which was previously related to the presence of hepatitis B e antigen in serum and hepatitis B core antigen in liver cells. In liver tissue different molecular patterns can be recognized as free viral DNA and integrated sequences. Furthermore, introduction of the polymerase chain reaction allows the detection of very small amounts of vi…