[Hepatitis C virus genotyping: comparison of the Abbott RealTime HCV Genotype II assay and NS5B sequencing]

Abstract

Purpose of the study: Hepatitis C virus genotyping is needed for treatment decision and monitoring. The results of a genotyping assay based on real-time PCR and TaqMan chemistry were compared with the results of NS5B region sequencing.

Materials and methods: One hundred and two sera (genotypes 1-6) were tested. Amplification and detection of viral RNA were performed with the Abbott RealTime HCV Genotype II assay targeting 5'non-coded region (5'NC) for the identification of genotypes 1 to 6 and NS5B, for 1a and 1b subtypes detection. Sequencing of 5'NC fragment was used to resolve discrepant results.

Results: No indeterminate results were obtained. Concordance with NS5B sequencing was 93% (95 on 102), 96% at the genotype level (98 on 102) and 93% for genotype 1 subtyping (40 on 43). Discordant genotyping results were a 2f subtype identified as 5, a 6a typed as 1, a 3a identified as a 1-3 co-infection and a 4r identified as a 1-4 co-infection. Discordant subtyping results were 2 1b subtypes only typed as 1 and a 1e identified as 1a.

Conclusion: Abbott RealTime HCV Genotype II assay is a rapid, automated and simple to interpret method for HCV genotyping. It allows the detection of possible mixed infections which might have a negative impact on therapeutic response. However, the discrepant results found in this small series underline the need for assay optimization.