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| 2. |
- Neumüller, M, et al.
(författare)
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HIV-1 reverse transcriptase inhibiting antibody titer in serum : relation to disease progression and to core-antibody levels.
- 1992
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Ingår i: Journal of Medical Virology. - : Wiley. - 0146-6615 .- 1096-9071. ; 36:4, s. 283-291
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Tidskriftsartikel (refereegranskat)abstract
- A new assay for detecting inhibition of reverse transcriptase activity (the RT-i REA) was developed. This assay was standardized for screening serum samples for reverse transcriptase inhibiting antibodies (RT-iAb). High specificity (100%) and sensitivity (greater than 98%) were achieved with samples from HIV-negative individuals and HIV-infected individuals. The RT-i REA was also used in a study of the titers of RT-iAb in serum samples obtained from 33 HIV-infected homosexual men. The results confirmed the relation between decreasing RT-iAb levels and progression to late stages of the disease. Furthermore, a falling RT-iAb titer was observed in 14 of 15 individuals experiencing periods of severe clinical symptoms attributed to HIV-activity. In 7 of the patients the decline in RT-iAb titer began prior to severe clinical symptoms. The fall in RT-iAb titer also correlated with a reduction in core Ab level. The core Ab level has previously been reported to be a disease progression marker with considerable prognostic value. However, whereas all patients were positive for RT-iAb, 8 of the 33 patients did not have detectable core Ab. The use of RT-iAb titer as a marker of disease progression is discussed.
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| 3. |
- Neumüller, Magnus, et al.
(författare)
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HIV reverse transcriptase inhibiting antibodies detected by a new technique : relation to p24 and gp41 antibodies, HIV antigenemia and clinical variables.
- 1991
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Ingår i: Journal of Medical Virology. - : Wiley. - 0146-6615 .- 1096-9071. ; 34:1, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- A new assay for HIV reverse transcriptase activity inhibiting antibodies (RTI-ab) was used for the analysis of a large collection of sera sampled before and after confirmation of HIV infection. In this assay HIV-RT was preincubated with diluted serum, after which residual RT activity was determined by a technique using a template coupled to macrobeads and 125I-lodo-deoxyuridine-triphosphate as the tracer-substrate. Of the 936 sera analysed, 818 were found positive for RTI-ab, and 824 were positive in Western blot (Wb). The prevalence of RTI-ab compared to Wb was therefore 99.3%. The corresponding figure for 930 sera analysed for envelope-ab, i.e., gp41-ab, was 823 positive, and of these 930 sera 815 were Wb positive, giving a comparative prevalence of 101%. In contrast, only 678 samples of 993 analyzed for core ab, i.e., p24, were positive, giving a prevalence of 77.0% as 880 of these samples were Wb positive. Thus, RTI-ab was as prevalent as gp41-ab, and although the analyses of RTI-ab amounts in different stages showed decreasing levels in stage IV compared to stages II or III, all of the sera except 1 were found positive in stages III and IV. Further, it was found that both the few RTI-ab negative samples in stage II and the few RTI-ab positive samples among Wb negative sera were sampled in connection with seroconversion. The specificity of the RTI-ab assay was 100% in a test of 200 serum samples from HIV negative blood donors. It was concluded that RTI-ab analyses can be made highly sensitive and specific and useful for studies of HIV infection.
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| 4. |
- Nordenfelt, E, et al.
(författare)
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Hepatitis C virus infection in hemodialysis patients in southern Sweden: epidemiological, clinical, and diagnostic aspects
- 1993
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Ingår i: Journal of Medical Virology. - : Wiley. - 1096-9071 .- 0146-6615. ; 40:4, s. 266-270
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Tidskriftsartikel (refereegranskat)abstract
- A prevalence of hepatitis C virus (HCV) antibodies of 12% was found in 276 patients from 11 dialysis units. Between zero and 22% of the patients in the different units were anti-HCV positive. The epidemiology of HCV was studied in two units during a 2 year period by antibody assays and the polymerase chain reaction and correlated with clinical manifestations. Two types of epidemiologic patterns were found that may explain the wide difference of HCV prevalence described in different dialysis units. In one unit there was no evidence of spread within the unit, and the prevalence of HCV was dependent on the status of the patients entering for treatment. In the other unit, a clustering of infected patients could be seen in which 13 of 36 were infected during a 3 year period. Some patients who had not received blood transfusions were among the infected. Hepatitis C infection was the most common explanation for repeated abnormal transferase levels. Most of the HCV-infected patients reacted both for anti-HCV and HCV RNA. HCV RNA was in general detected earlier than anti-HCV seroconversion. Among 20 HCV RNA-positive serum samples that were anti-HCV ELISA-positive 18 had indeterminate and two negative reactions by immunoblot (RIBA 2). Thus the RIBA 2 test should be used with caution as a confirmatory antibody test in this group of patients.
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| 5. |
- Widell, Anders, et al.
(författare)
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Genotyping of hepatitis C virus isolates by a modified polymerase chain reaction assay using type specific primers: epidemiological applications
- 1994
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Ingår i: Journal of Medical Virology. - : Wiley. - 1096-9071 .- 0146-6615. ; 44:3, s. 272-279
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Tidskriftsartikel (refereegranskat)abstract
- A polymerase chain reaction (PCR)-based assay using primers against the hepatitis C core gene has been described [Okamoto et al. (1992a): Journal of General Virology 73:673-679]. Within the two major HCV genotypes 1 and 2, the Okamoto system identifies two subtypes each (1a, 1b and 2a, 2b, respectively). Typing is achieved by a primary PCR with consensus primers followed by a nested PCR with type specific primers. The original assay was modified by addition of a parallel second PCR identifying the recently described major genotype 3. The assay also identifies in duplicate subtype 1b (type II by Okamoto), suggested to respond poorly to interferon. Reaction conditions were reviewed and melting temperatures of all typing primers equalised to increase strigency. The modified system functioned well and typing results were supported by partial core sequencing. The following distribution of genotypes was found in 53 hepatitis C virus (HCV) infected Swedish blood donors: genotype 1a (57%), 3 (19%), 1b (13%), and 2b (11%). In six recipients of HCV infected blood identified in a retrospective study, the recipient HCV genotype was identical to donor HCV genotype. Furthermore, in HCV positive couples identical genotype was observed when only one partner had an external risk factor; whereas genotypes were often diverse if both sex partners had parenteral risk factors. Finally, a cluster of hepatitis C cases in a haemodialysis unit was evaluated retrospectively. Eight patients had genotype 1b, two had mixed 1a and 1b, and one had type 1a. The modified HCV genotyping assay was of value in examining different epidemiological situations and can be expanded presumably to include future genotypes.
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| 6. |
- Widell, Anders, et al.
(författare)
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Hepatitis C virus RNA in blood donor sera detected by the polymerase chain reaction: comparison with supplementary hepatitis C antibody assays
- 1991
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Ingår i: Journal of Medical Virology. - : Wiley. - 1096-9071 .- 0146-6615. ; 35:4, s. 253-258
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Tidskriftsartikel (refereegranskat)abstract
- The low specificity of screening ELISAs for antibodies to hepatitis C virus in blood donors has called for confirmatory tests. Two types of supplementary antibody assays are available, recombinant immunoblot assays (RIBA-1 and RIBA-2) and an antibody consumption test referred to as a neutralization assay. Amplification of viral nucleic acid by the polymerase chain reaction (PCR) provides an antibody independent mode of detecting viral infection. We applied reverse transcription-double PCR to detect an HCV 5'-noncoding viral RNA sequence in serum specimens and compared PCR findings with confirmatory antibody tests. This study includes sera from 37 blood donors found positive by the Ortho anti-HCV (C100-3) ELISA out of 14,591 donations. Of the 37 positive sera, 8 were positive by RIBA-1 and 1 further by RIBA-2. Seven of the RIBA positive sera contained HCV RNA by PCR. Among the 8 indeterminate and the 21 negative donor sera by RIBA-I, no PCR positive serum was found. The 37 anti-HCV positive donor sera identified by Ortho ELISA were also tested by Abbott anti-HCV (C100-3) ELISA whereby 22 were positive. Of these 22 sera plus 1 further with ELISA OD just below cutoff, 8 were positive by the neutralization assay, (Abbott Laboratories, North Chicago, IL, USA) and 6 of these, including the borderline serum, were PCR positive. One of the two neutralizable but PCR negative sera was RIBA positive and the other was indeterminate. However, one ELIS. A (Abbott Laboratories) positive (OD 1.99) serum was not neutralizable but nevertheless contained HCV RNA by PCR. Thus in blood donor sera, anti-HCV (C100-3) reactivity confirmed by RIBA or neutralization correlated well with the presence of HCV RNA.
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