Search results for "Virology"
showing 10 items of 2354 documents
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…
Mosaic particles formed by wild-type hepatitis B virus core protein and its deletion variants consist of both homo- and heterodimers.
2003
AbstractCo-expression in Escherichia coli of wild-type (wt) hepatitis B virus core protein (HBc) and its naturally occurring variants with deletions at amino acid positions 77–93 or 86–93 leads to formation of mosaic particles, which consist of three dimer subunit compositions. These compositions are wt/variant HBc heterodimers and two types of homodimers, formed by wt HBc or the variant HBc themselves. Mosaic particles were found also when both HBc deletion variants 77–93 and 86–93 were co-expressed in E. coli. These findings are discussed in terms of their significance for hepatitis B virus pathogenesis and prospective use of mosaic particles in vaccine development.
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…
Anti-rat liver microsomal and cytosolic antibodies in hepatitis C virus infection.
1994
In order to assess the frequency of autoimmunity markers in hepatitis C virus infection, 229 RIBA 2 HCV positive individuals were tested by ELISA and Immunoblot assay using as antigen rat liver microsomal and cytosolic proteins. Twenty-one out of 229 individuals (9%) showed anti-rat liver microsome antibodies by ELISA, but the titre was low (1:100 to 1:1,600). In Immunoblot, only 5 of these 21 ELISA positive sera recognized also rat liver microsomal proteins (MW between 30 to 64 kDa). Antibodies against rat liver cytosolic proteins were found by ELISA in 14 out of 229 individuals (6%). Three of them showed a reactivity in Immunoblot to 42 kDa or 55 kDA proteins. In conclusion, HCV infection…
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…
Mutations in hepatitis C virus RNAs conferring cell culture adaptation.
2001
ABSTRACT As an initial approach to studying the molecular replication mechanisms of hepatitis C virus (HCV), a major causative agent of acute and chronic liver disease, we have recently developed selectable self-replicating RNAs. These replicons lacked the region encoding the structural proteins and instead carried the gene encoding the neomycin phosphotransferase. Although the replication levels of these RNAs within selected cells were high, the number of G418-resistant colonies was reproducibly low. In a search for the reason, we performed a detailed analysis of replicating HCV RNAs and identified several adaptive mutations enhancing the efficiency of colony formation by several orders of…
Refined analysis of genetic variability parameters in hepatitis C virus and the ability to predict antiviral treatment response.
2008
Summary. Hepatitis C virus (HCV) infects approximately 3% of the world population. The chronicity of hepatitis C seems to depend on the level of genetic variability. We have recently (Torres-Puente et al., J Viral Hepat, 2008; 15: 188) reported genetic variability estimates from a large-scale sequence analysis of 67 patients infected with HCV subtypes 1a (23 patients) and 1b (44 patients) and related them to response, or lack of, to alpha-interferon plus ribavirin treatment.. Two HCV genome regions were analysed in samples prior to antiviral therapy, one compressing the three hypervariable regions of the E2 glycoprotein and another one including the interferon sensitive determining region …
Hepatitis C virus antibody secretion in vitro by peripheral blood lymphocytes.
1992
A recombinant polypeptide corresponding to a virus-specific cDNA clone (c100-3) serves as the antigen for a hepatitis C virus (HCV) antibody assay. Previous investigations have shown an 80% prevalence of HCV antibodies in sera of patients suffering from post-transfusional chronic hepatitis non-A, non-B, but positive results were also obtained for 30 to 70% of sera from patients with chronic hepatitis B or autoimmune hepatitis. In this study we show that HCV antibodies are secreted by peripheral blood lymphocytes (PBL) in vitro. PBL from 12/35 patients with chronic non-A, non-B hepatitis and 1/6 patients with chronic active hepatitis B spontaneously secreted HCV antibodies in cell culture su…
Novel artemisinin derivatives with potential usefulness against liver/colon cancer and viral hepatitis.
2013
Antitumor and antiviral properties of the antimalaria drug artemisinin from Artemisia annua have been reported. Novel artemisinin derivatives (AD1-AD8) have been synthesized and evaluated using in vitro models of liver/colon cancer and viral hepatitis B and C. Cell viability assays after treating human cell lines from hepatoblastoma (HepG2), hepatocarcinoma (SK-HEP-1), and colon adenocarcinoma (LS174T) with AD1-AD8 for a short (6h) and long (72h) period revealed that AD5 combined low acute toxicity together with high antiproliferative effect (IC50=1-5μM). Since iron-mediated activation of peroxide bond is involved in artemisinin antimalarial activity, the effect of iron(II)-glycine sulfate …