[Comparison of different methods of hepatitis C virus genotyping]

In order to introduce the approach of HCV genotyping in our laboratory, a comparative study of 3 molecular and 1 serological methods, was conducted on 62 HCV RNA positive sera. The molecular genotyping methods target the 5'untranslated (UTR) region of the virus genome and are based on an amplification of the viral genome, followed by partial sequencing, analyses of restriction fragment length polymorphisms (RFLP) or molecular hybridation (Inno LiPA, Innogenetics). The serological method or serotyping is based on the detection of antibodies to genotype specific epitopes derivated from the Non Structural (NS) 4 region of the viral genome (HCV 1-6 Serotyping Assay, Murex Biotech). "In house" methods, sequencing and RFLP, identified the genotype for 13 samples classified as non-typables by commercial kits Inno LiPA test and HCV 1-6 Serotyping Assay. Mixed infections revealed, especially by Inno LiPA, could not be identified by partial sequencing, which seems to detect only predominant genotype. For 4 samples, genotyping results of the methods targeting the 5'UTR were discordant with those of the serotyping of the NS4 region. Commercial kits are efficient to determine HCV genotypes, particularly in the context of antiviral therapy and patient's follow-up, sequencing remains the best alternative for more complete characterisation of viral strains and for epidemiological investigations.