The cobas® HCV GT is a new tool that accurately identifies Hepatitis C virus genotypes for clinical practice

OBJECTIVE We aimed to evaluate the correct assignment of HCV genotype/subtypes 1a and 1b by cobas® HCV genotyping (GT) assay (Roche Molecular Diagnostics) compared with nonstructural protein 5B (NS5B) sequencing. PATIENTS AND METHODS Clinical samples from 153 patients submitted for HCV genotyping were studied. After genotyping with the cobas® HCV GT, sequencing of a 387 bp fragment in the NS5B gene and phylogenetic analysis was employed to compare genotyping results. Major discrepancies were defined as differences in the assigned genotype by cobas® HCV GT and NS5B sequencing (including genotype 1 subtypes 1a and 1b misclassification). RESULTS Overall agreement between the cobas® HCV GT and NS5B sequencing was 98%; all the 1a, 1b, 2, 3 and 4 genotypes identified by cobas® HCV GT were concordant with NS5B sequencing. Three samples tested "indetermined" by cobas® HCV GT assay and were genotyped as 1a, 3a, and 4d by NS5B sequencing. CONCLUSSION These results indicate that the cobas® HCV GT assay correctly identifies HCV genotypes, and points out the importance of additional methods based on DNA sequencing for resolving indeterminate results.