Enzyme immunoassay for separate detection of anti-HCV antibodies to individual HCV antigens as a confirmatory assay in diagnostics of HCV infection

Abstract

Dijagnostika hepatitisa C temelji se na određivanju protutijela anti-HCV probirnim imunoenzimskim testovima (EIA). Svaki reaktivni nalaz anti-HCV probirnog testa prema recentnim smjernicama zahtijeva daljnje određivanje HCV RNK. U slučajevima negativnog nalaza HCV RNK, reaktivni nalaz EIA anti-HCV treba potvrditi imunoblot testom (IB). Komercijalno su dostupni i EIA testovi koji imaju mogućnost određivanja specifičnih protutijela na pojedinačne antigene HCV koji daju rezultate usporedive sa standardnim potvrdnim IB testovima. Cilj ovog rada bio je prikazati EIA potvrdni test, EIA-Anti-HCV-Spectrum (DSI, Italija) i usporediti rezultate testiranja sa standardnim IB testom. Analizirali smo 50 nasumično odabranih seruma koji su imali reaktivni odgovor protutijela na HCV u probirnom EIA testu (Monolisa HCV Ag-Ab ULTRA, Bio-Rad, Francuska). Za isključenje lažno pozitivnih rezultata serumi su dalje testirani potvrdnim IB testom (Deciscan HCV PLUS, Bio-Rad, Francuska). Odabranih 50 uzoraka testirano je testom EIA-Anti-HCV-Spectrum za određivanje pojedinačnih protutijela anti-HCV na antigene jezgre te antigene NS3, NS4 i NS5. Od 50 seruma s reaktivnim odgovorom protutijela na HCV u probirnom testu u oba potvrdna testa pozitivno je bilo 40, negativno 1 i granično 3 uzorka. Nepodudarnih rezultata potvrdnih testova bilo je 6: svi su bili granično pozitivni u IB testu, a negativni u alternativnom potvrdnom testu EIA-Anti-HCV-Spectrum. Predstavili smo imunoenzimski potvrdni test za protutijela anti-HCV koji je pokazao dobru korelaciju sa standardnim imunoblot testom premda je potrebno napraviti evaluaciju na ve}em broju uzoraka za sigurnije zaključke.Diagnostics of hepatitis C is based on the determination of anti-HCV antibodies by screening enzyme immunoassays (EIA). Each reactive anti-HCV screening result, according to recent guidelines, requires further determination of HCV RNA. In cases of negative HCV RNA findings, reactive anti-HCV results should be confirmed by immunoblotting (IB). Alternative confirmatory EIA with the ability to determine the antibodies against individual HCV antigens, which are comparable with the results of immunoblot tests, are commercially available. The aim of this study was to present an EIA test, the EIA-Anti-HCV-Spectrum (DSI, Italy) and compare the test results with standard IB test. We analyzed 50 randomly selected serum samples with reactive screening EIA (Monolisa HCV Ag-Ab ULTRA, Bio-Rad, France) results. In order to exclude false positives, serum samples were further tested with confirmatory IB test (Deciscan HCV PLUS, Bio-Rad, France). A total of 50 selected samples were tested with EIA-Anti-HCV-Spectrum for separate detection of anti-HCV antibodies against core, NS3, NS4 and NS5 antigens. Out of the 50 primary reactive samples, anti-HCV antibodies were positive in both confirmatory tests in 40, negative in 1 and borderline in 3 samples. Discordant results of confirmatory tests were recorded in 6 samples: all borderline in IB test and negative in the alternative EIA-Anti-HCV-Spectrum test. We present an EIA confirmatory test for anti-HCV antibodies which showed a good correlation with the standard immunoblot test, although it is ecessary to perform the evaluation on a large number of samples for safer conclusions