Search results for "Replica"
showing 10 items of 576 documents
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…
Hepatitis viruses: live and let die.
2007
Viral hepatitis is a diffuse inflammatory reaction of the liver caused by hepatotropic viruses. Among the hepatitis viruses, only hepatitis B virus and hepatitis C virus are able to persist in the host and cause chronic hepatitis. In the course of persistent infection, inflammation forms the pathogenetic basis of chronic hepatitis that can lead to nodular fibrosis, which can progress to cirrhosis and, eventually, hepatocellular carcinoma (HCC). Of the different antiviral defense systems employed by the host, apoptosis significantly contributes to the prevention of viral replication, dissemination, and persistence. Pathomorphologic studies have shown acidophilic bodies and hepatocyte dropout…
Hepatitis B virus maturation is sensitive to functional inhibition of ESCRT-III, Vps4, and gamma 2-adaptin.
2007
ABSTRACT Hepatitis B virus (HBV) is an enveloped DNA virus that presumably buds at intracellular membranes of infected cells. HBV budding involves two endocytic host proteins, the ubiquitin-interacting adaptor γ2-adaptin and the Nedd4 ubiquitin ligase. Here, we demonstrate that HBV release also requires the cellular machinery that generates internal vesicles of multivesicular bodies (MVBs). In order to perturb the MVB machinery in HBV-replicating liver cells, we used ectopic expression of dominant-negative mutants of different MVB components, like the ESCRT-III complex-forming CHMP proteins and the Vps4 ATPases. Upon coexpression of mutated CHMP3, CHMP4B, or CHMP4C forms, as well as of ATPa…
Myristylation is involved in intracellular retention of hepatitis B virus envelope proteins
1991
The envelope of hepatitis B virus contains three related proteins, one of which is myristylated. The nonmyristylated small and middle protein are assembled into empty envelope particles which are secreted from cells, whereas the myristylated large envelope protein is mainly found in complete virions and is not secreted in the absence of the nucleocapsid. The block to secretion can be partially overcome by mutation or deletion of the myristylation site. Creation of a myristyl attachment site in the small protein impairs the secretion of empty envelope particles but not their intracellular assembly. Myristylation may therefore play a crucial role in hepatitis B virus replication by channeling…
Quantitation of HCV-replication using one-step competitive reverse transcription-polymerase chain reaction and a solid phase, colorimetric detection …
1994
A solid phase assay for the colorimetric detection of competitively amplified HCV-cDNA has been established and used to investigate clinical samples from patients with chronic hepatitis. The assay is based on the reduction in the amplification of an hepatitis C virus-related competitor molecule by wild-type hepatitis C virus during polymerase chain reaction. The internal standard contains a lac operator sequence, allowing the amount of amplified competitor to be determined using a lac I-repressor/beta-galactosidase fusion protein. The reduction in the amplification of competitor is dependent upon the concentration of HCV-RNA in the original sample. External hepatitis C virus wild-type stand…
Characterization of cell lines carrying self-replicating hepatitis C virus RNAs.
2001
ABSTRACT Subgenomic selectable RNAs of the hepatitis C virus (HCV) have recently been shown to self-replicate to high levels in the human hepatoma cell line Huh-7 (V. Lohmann, F. Körner, J. O. Koch, U. Herian, L. Theilmann, and R. Bartenschlager, Science 285:110–113, 1999). Taking advantage of this cell culture system that allows analyses of the interplay between HCV replication and the host cell, in this study we characterized two replicon-harboring cell lines that have been cultivated for more than 1 year. During this time, we observed no signs of cytopathogenicity such as reduction of growth rates or ultrastructural changes. High levels of HCV RNAs were preserved in cells passaged under…
Sequences in the 5′ Nontranslated Region of Hepatitis C Virus Required for RNA Replication
2001
ABSTRACT Sequences in the 5′ and 3′ termini of plus-strand RNA viruses harbor cis -acting elements important for efficient translation and replication. In case of the hepatitis C virus (HCV), a plus-strand RNA virus of the family Flaviviridae , a 341-nucleotide-long nontranslated region (NTR) is located at the 5′ end of the genome. This sequence contains an internal ribosome entry site (IRES) that is located downstream of an about 40-nucleotide-long sequence of unknown function. By using our recently developed HCV replicon system, we mapped and characterized the sequences in the 5′ NTR required for RNA replication. We show that deletions introduced into the 5′ terminal 40 nucleotides abolis…