Quantitative signal of anti-HCV by an automated assay predicts viremia in a population at high prevalence of hepatitis C virus infection.
OBJECTIVE
The diagnosis of ongoing hepatitis C virus (HCV) infection involves the detection of specific antibodies and of HCV-RNA. We aimed to assess the relationship between these two parameters in a representative sample of a population at high risk for HCV infection.


METHODS
Plasma and serum samples were respectively tested for HCV-RNA by a qualitative PCR (Cobas Amplicor HCV, Roche) and for HCV antibodies by a MEIA screening assay (AxSYM HCV 3.0, Abbott) and an immunoblot (Inno-LIA-III, Innogenetics).


CONCLUSIONS
Out of 888 samples assayed, 579 (65.2%) were positive for HCV-RNA, while anti-HCV antibodies were detected respectively in 802 sera by AxSYM (90.3%) and in 783 by LIA (706 positive and 77 indeterminate, 88.2%). The anti-core antibodies displayed the best correlation with viremia, since they were present in 97.1% of the PCR+ samples, followed by anti-NS3 (90.2%) and anti-NS4 (89.6%). Only one HCV-RNA positive sample was negative by LIA and MEIA (early seroconversion). The AxSYM sample/cutoff (S/CO) values were directly correlated with the presence of HCV-RNA: a PCR positivity was found in 4.9% of samples with a S/CO < or =10, in 60.8% of samples with a S/CO between 11 and 50 and in 93.6% of cases with a S/CO >50, (P < 0.005). The immunoblot adds little, on a single specimen, to the information yielded by the AxSYM screening test. A suitable diagnostic algorithm for HCV in high-risk settings could be the anti-HCV screening by MEIA and a qualitative assay for HCV-RNA on samples with low reactivity.
Bossi
Vincenzo
V
Virology, Ospedale Amedeo di Savoia, corso Svizzera 164, 10100 Turin, Italy.
Galli
Claudio
C
D001331:Automation; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D006526:Hepatitis C / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D018937:Hepatitis C Antibodies / Q000097:blood*; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D012367:RNA, Viral / Q000097:blood; D011933:Reagent Kits, Diagnostic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014758:Viral Core Proteins / Q000276:immunology; D014759:Viral Envelope Proteins / Q000276:immunology; D017361:Viral Nonstructural Proteins / Q000276:immunology; D014766:Viremia / Q000175:diagnosis; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; D012324:RNA-Dependent RNA Polymerase
D018937:Hepatitis C Antibodies; D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic; D014758:Viral Core Proteins; D014759:Viral Envelope Proteins; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C093542:NS4 protein, hepatitis C virus; C069130:nucleocapsid protein, Hepatitis C virus; C091015:glycoprotein E2, Hepatitis C virus; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase