This analysis provides evidence for the good sensitivity and specificity of ELISA3 assays particularly in high risk patient groups and confirms their use for screening in these populations. Further studies are needed to assess properly RIBA3 in general population and in risk patients. Clinical importance of HCV confirmatory testing in blood donors. HCV confirmatory testing of blood donors. Use of aminotransferase, hepatitis C antibody, and hepatitis C polymerase chain reaction RNA assays to establish the diagnosis of hepatitis C virus infection in a diagnostic virology laboratory.
Indeterminate second-generation hepatitis C recombinant immunoblot test: detection of hepatitis C virus infection by polymerase chain reaction. J Infect Dis. Detection of hepatitis C virus sequences in sera with controversial serology by nested polymerase chain reaction. Indeterminate hepatitis C. Learn More. Hepatitis C virus HCV infects approximately million individuals worldwide.
Prevention of HCV infection complications is based on antiviral therapy with the combination of pegylated interferon alfa and ribavirin. The use of serological and virological tests has become essential in the management of HCV infection in order to diagnose infection, guide treatment decisions and assess the virological response to antiviral therapy. The HCV genotype should be systematically determined before treatment, as it determines the indication, the duration of treatment, the dose of ribavirin and the virological monitoring procedure.
HCV RNA monitoring during therapy is used to tailor treatment duration in HCV genotype 1 infection, and molecular assays are used to assess the end-of-treatment and, most importantly the sustained virological response, i. Chronic HCV infection has been estimated to be responsible for approximately to deaths per year, essentially related to decompensation of cirrhosis, end-stage liver disease and hepatocellular carcinoma. The use of serological and virological tests has become essential in the management of HCV infection in order to diagnose infection, and most importantly guide treatment decisions and assess the virological response to antiviral therapy.
HCV is a member of the Flaviviridae family, genus Hepacivirus[ 2 ]. Six HCV genotypes[ 1 - 6 ] and a large number of subtypes 1a, 1b, 1c, etc. HCV only natural host is man. All HCV genotypes have a common ancestor virus.
In these areas, a large number of subtypes of these genotypes are found[ 2 ]. The rest of the world, in particular industrialized areas, harbor a small number of HCV subtypes that could widely spread because they met an efficient route of transmission, such as blood transfusion or the intravenous use of drugs. They include genotypes 1a, 1b, 2a, 2b, 2c, 3a, 4a and 5a[ 2 ].
The HCV virion is made of a single-stranded positive RNA genome, contained into an icosahedral capsid, itself enveloped by a lipid bilayer within which two different glycoproteins are anchored[ 3 ]. The 3' UTR has been divided into three regions: a variable sequence of approximately 40 bases, a variable length poly-UC rich tract, and a highly conserved 98 base region.
The HCV lifecycle starts with virion attachment to its specific receptor[ 3 ]. The HCV lifecyle is poorly known because of the lack, until very recently, of a productive culture system. It is supposed, by analogy with the Flaviviridae, that the virus linked to its receptor complex is internalized, and that the nucleocapsid is released into the cytoplasm. The virus is decapsidated, and the genomic HCV RNA is used both for polyprotein translation and replication in the cytoplasm.
Replication and post-translational processing appear to take place in a membranous web made of the non-structural proteins and host cell proteins called "replication complex", located in close contact with perinuclear membranes. Genome encapsidation appears to take place in the endoplasmic reticulum and nucleocapsids are enveloped and matured into the Golgi apparatus before newly produced virions are released in the pericellular space by exocytosis[ 3 ].
Recombinant antigens are used to capture circulating anti-HCV antibodies onto the wells of microtiter plates, microbeads, or specific holders adapted to closed auto-mated devices.
The presence of anti-HCV antibodies is revealed by anti-antibodies labeled with an enzyme that catalyzes the transformation of a substrate into a colored compound. Their sensitivity is more difficult to determine, given the lack of a gold standard method, but it is excellent in HCV-infected immunocompetent patients. EIAs can be fully automated and are well adapted to large volume testing.
Mixed serological reactivities can be observed that could be related to mixed infection although cross-reactivity or recovery from one genotype infection and persistence of viremia with another genotype cannot be ruled out. HCV RNA is extracted and reverse transcribed into a single-stranded complementary DNA cDNA , which is subsequently processed into a cyclic enzymatic reaction leading to the generation of a large number of detectable copies.
Detection of amplified products is achieved by hybridizing the produced amplicons onto specific probes after the reaction in "classic" PCR or TMA techniques[ 8 ].
In "real-time" PCR, each round of amplification leads to the emission of a fluorescent signal and the number of signals per cycle is proportional to the amount of HCV RNA in the starting sample[ 8 - 10 ].
Five standardized assays are commercially available. Detection of hepatitis C virus infection with recombinant immunoblot assay, synthetic immunoblot assay, and polymerase chain reaction. J Clin Lab Anal. Detection of antibody to hepatitis C virus by second-generation enzyme immunoassay. Am J Clin Pathol. Third-generation recombinant immunoblot assay to confirm hepatitis C virus-indeterminate serological samples.
Vox Sang. Improved detection of antibodies to hepatitis C virus by use of a new recombinant immunoblot assay. Second-generation anti-HCV tests predict infectivity. Evaluation of laboratory assays for screening antibody to hepatitis C virus. Detection of chronic hepatitis C virus infection by four diagnostic systems: first-generation and second-generation enzyme-linked immunosorbent assay, second-generation recombinant immunoblot assay and nested polymerase chain reaction analysis.
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