Evaluation of third-generation screening and confirmatory assays for HCV antibodies.
A third-generation (gen.) screening and immunoblot assay (Ortho EIA-3.0; Chiron RIBA-3 prototype), using antigens derived from the capsid and different nonstructural regions (NS3, NS4 and NS5) of the hepatitis C virus viral genome, were evaluated in comparison with the corresponding second-gen. assays (Ortho EIA-2.0; revised Ortho EIA-2.5; Chiron RIBA-2). In 203 depository sera of blood donors, positive in EIA-2.0, specificity of the screening assays was improved as shown by an increase in positive predictive value for viral carrier state from 0.23 (EIA-2.0) to 0.37 (EIA-2.5) and 0.52 (EIA-3.0). Comparing the confirmation patterns on RIBA-2 and RIBA-3, this amelioration was mainly due to the specific elimination of false-positive c22-3 and c100-3 reactions. Antibody response to the newly added NS5 antigen was not as prevalent as to the other antigens and had only a minor influence in sample allocation. In contrast, screening of 1,560 volunteer blood donors and 47 hemodialysis patients revealed 3 additional positive sera, only reacting with the NS5 antigen. However none of these isolated NS5 reactions could be confirmed on synthetic peptides [INNO-LIA: NS5(p)] and none was PCR positive. A documented seroconversion, detected earlier with EIA-3.0, was related to a better immunological response to the NS3 antigen and not to the additional NS5. From this pilot study third-gen. assays appeared extremely useful in the reevaluation of HCV-seropositive depository sera. However the additional value of the NS5 antigen in blood donor screening is still hypothetical and remains to be established in larger screening studies.
Uyttendaele
S
S
Belgian Red Cross Blood Transfusion Center, Leuven.
Claeys
H
H
Mertens
W
W
Verhaert
H
H
Vermylen
C
C
D000956:Antigens, Viral / Q000276:immunology; D001782:Blood Donors; D002213:Capsid / Q000276:immunology; D015331:Cohort Studies; D005189:False Positive Reactions; D016174:Hepacivirus / Q000276:immunology* / Q000302:isolation & purification; D006508:Hepatitis Antibodies / Q000097:blood*; D006526:Hepatitis C / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission; D018937:Hepatitis C Antibodies; D018936:Hepatitis C Antigens; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D008403:Mass Screening / Q000379:methods*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D010865:Pilot Projects; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000276:immunology; D006435:Renal Dialysis; D012680:Sensitivity and Specificity; D017361:Viral Nonstructural Proteins / Q000276:immunology; D014766:Viremia / Q000382:microbiology
D000956:Antigens, Viral; D006508:Hepatitis Antibodies; D018937:Hepatitis C Antibodies; D018936:Hepatitis C Antigens; D010446:Peptide Fragments; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins