COMPARISON OF HEPATITIS-C VIRUS SEROTYPING AND GENOTYPING IN FRENCH PATIENTS

Background: Hepatitis C virus (HCV) serotyping has been proposed as an alternative assay to determine the respective genotype as it is more rapid, simple and less expensive than polymerase chain reaction (PCR) based typing methods. Objectives: A serotyping assay was compared with a genotyping assay to determine the infecting hepatitis C virus type in chronically HCV infected patients eligible for interferon therapy. Study design: An enzyme immunoassay (HC01, Murex(TM)) was tested to id entify HCV types 1, 2 and 3 specific antibodies in 134 PCR-positive se ra from chronically infected patients which had been previously genoty ped by a reverse hybridization assay (INNO-LiPA HCV I, Innogenetics). Respectively nine and seven sera were from HIV-seropositive and hemodi alysis patients. Unreactive sera and those with discrepant results wer e retested by a new version (HC02) extended to types 4, 5 and 6. Resul ts: The distribution frequency of HCV genotypes was subtype 1a, 16.4%; subtype 1b, 46.3%; subtype 2a, 7.5%; subtype 3a, 20.9%; type 4, 4.5%; type 5, 0.7%; and co-infections, 3.7%. Among all the patients, 95% we re of type I, 2 or 3. The antibody reactivities of hemodialysis (1/7; P < 0.05) and HIV-seropositive patients (4/9; P = 0.06) were lower tha n for the patients seen at the hepatology unit (87/118). For these lat ter patients, the serotyping assay was interpretable in 71% and concor dant in 64% of the samples with the genotyping assay. Out of the 84 sa mples with interpretable results, 75 sera were correctly serotyped (89 % specificity). The two mixed results obtained by serotyping did not c orrespond to genotype coinfections (n=3) and reciprocally. Six discrep ancies were ruled out by the new assay, but the 2 untypeable sera rema ined unsolved, and four out of six sera with genotype 4 were serotyped as type 5. Conclusions: Serotyping could be an attractive approach if the reactivity was improved and the subtyping possible. (C) 1997 Else vier Science B.V.