| 1. |
- Viazov, Sergei, et al.
(författare)
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Typing of hepatitis C virus isolates by DNA enzyme immunoassay
- 1994
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Ingår i: Journal of Virological Methods. - : Elsevier BV. - 1879-0984 .- 0166-0934. ; 48:1, s. 81-91
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Tidskriftsartikel (refereegranskat)abstract
- Recently, at least six types of hepatitis C viruses (HCV) have been identified. Different types of HCV appear to possess different pathogenic properties and a different sensitivity to interferon treatment. Typing of HCV isolates may therefore be an important diagnostic procedure. We report on a new method for identification of HCV types 1a, 1b, 2a, 2b and 3a which are most prevalent in Europe, North America and Japan. The assay is based on a combination of two well established techniques, the polymerase chain reaction (PCR) and DNA enzyme immunoassay (DEIA). In the first step of the method a cDNA of about 250 bp corresponding to the HCV core-region is amplified by nested PCR. The target cDNA is then hybridized to type-specific oligonucleotides fixed to a solid phase through an avidin-biotin bridge. The formed hybrids are detected by a standard ELISA using monoclonal antibodies reacting with double-stranded DNA. Typically, signal-to-noise (S/N) ratios between 18.2 and 48.6 could be observed when different HCV types/subtypes were analyzed by this method. The test was evaluated using cloned HCV cDNAs of known types and by sequence determination of some of the typed cDNAs. Typing of 115 isolates from Germany, Russia and Turkey revealed that subtype 1b (59-100%) and 1a (24-32%) are most prevalent in these countries.
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| 2. |
- Bååth, Lena, et al.
(författare)
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A comparison between one first generation and three second generation anti-HCV ELISAs: an investigation in high- and low-risk subjects in correlation with recombinant immunoblot assay and polymerase chain reaction
- 1992
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Ingår i: Journal of Virological Methods. - 1879-0984. ; 40:3, s. 287-296
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Tidskriftsartikel (refereegranskat)abstract
- One first generation assay (manufactured by Ortho, test I) and 3 second generation anti-HCV ELISAs (manufactured by Ortho, Abbott, and UBI, tests II-IV) were compared. Sera from 4 different sources were used: (1) intravenous drug-users (IVDUs, n = 50), (2) blood donors (n = 1055), (3) all clinical samples from one day of routine anti-HCV testing (n = 89), (4) hemodialysis patients previously found negative by test I but clinically suspected to have a HCV infection (n = 11). Confirmatory anti-HCV tests were carried out with a second generation recombinant immunoblot assay (RIBA II). In sera positive exclusively by test IV, one antibody consumption test (UBI HCV Neutralization EIA) and one further immunoblot assay (INNO-LIA HCV Ab) were used. PCR for HCV RNA was carried out on all hemodialysis patient sera and in the RIBA II positive blood donor sera. The second generation ELISAs discriminated 11 more positive samples than the first generation test (2 IVDUs, 5 blood donors, 4 clinical samples). The 9 sera from blood donors and clinical samples were all RIBA II positive or indeterminate. The second generation tests thus showed increased sensitivity. The second generation tests also showed increased specificity in that 4 samples that were positive by test I but negative by the second generation tests, were also negative by RIBA II. With few exceptions, all RIBA II-positive and most of the indeterminate samples were positive by the second generation ELISAs. With few exceptions, all the RIBA II-negative samples were negative by the second generation ELISAs. Eleven blood donor sera were positive by test IV exclusively where RIBA II and other supplementary assays were negative. The recently introduced second generation anti-HCV ELISAs were found to have a higher sensitivity than the first generation test. The tests also showed a good concordance with the exception of test IV in the group of blood donor sera.
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