title: Multiplex real-time reverse transcription-PCR assay for determination of hepatitis C virus genotypes.
abstract: A variety of methods have been used to determine hepatitis C virus (HCV) genotypes. Because therapeutic decisions for chronic HCV-related hepatitis are made on the basis of genotype, it is important that genotype be accurately determined by clinical laboratories. Existing methods are often subjective, inaccurate, manual, time-consuming, and contamination prone. We therefore evaluated real-time reverse transcription-PCR (RT-PCR) reagents that have recently become commercially available (Abbott HCV Genotype ASR). The assay developed by our laboratory starts with purified RNA and can be performed in 4 to 5 h. An initial evaluation of 479 samples was done with a restriction fragment length polymorphism (RFLP) method and the RT-PCR assay, and discrepant samples were sequenced. An additional 1,200 samples were then tested, and data from all assays were used to evaluate the efficiency and specificity of each genotype-specific reaction. Good correlation between results by the two methods was seen. Discrepant samples included those indeterminate by the RT-PCR assay (n = 110) and a subset that were incorrectly called 2a by the RFLP method (n = 75). The real-time RT-PCR assay performed well with genotype 1, 2, and 3 samples. Inadequate numbers of samples were available to evaluate fully genotypes 4, 5, and 6. Analysis of each primer-probe set demonstrated that weak cross-reactive amplifications were common but usually did not interfere with the genotype determination. However, in about 1% of samples, two or more genotypes amplified at roughly equivalent amounts. Further studies are necessary to determine whether these mixed-genotype samples are true mixtures or a reflection of occasional cross-reactive amplifications.
authors.affiliation: Department of Laboratory Medicine, University of Washington Medical Center, Seattle, Washington 98195, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Cook
authors.forename: KaWing
authors.initials: K
authors.lastname: Sullivan
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Krantz
authors.forename: Arthur
authors.initials: A
authors.lastname: Bagabag
authors.forename: Keith R
authors.initials: KR
authors.lastname: Jerome
mesh_terms: D003429:Cross Reactions; D005838:Genotype; D016174:Hepacivirus / Q000145:classification* / Q000235:genetics; D012150:Polymorphism, Restriction Fragment Length; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity