title: Comparison of the Bayer VERSANT HCV RNA 3.0 and the Roche COBAS Amplicor HCV Monitor, Version 2.0, assays in HCV genotype 4 infection.
abstract: Prediction of treatment response is clinically important in chronic hepatitis C virus (HCV) genotype 4 infection. Early viral kinetics is useful in this respect for genotype 1 but interpretation is dependent on assay linearity and reproducibility. The VERSANT HCV RNA 3.0 (bDNA-3.0) and the COBAS Amplicor HCV Monitor 2.0 (HCM-2.0) have been widely used quantitative assays. We wanted to comparatively evaluate the two tests in a large genotype 4 sample. Genotyping was performed by NS5b sequencing. Viral load was tested in parallel in 32 patients at least six times on antiviral therapy with interferon alpha (IFNalpha). Totally, 198 samples within a quantitative range from undetectable to about 7 x 10(6) IU/mL (bDNA-3.0) were obtained and compared. Twenty-two samples with viral load above 500 000 IU/mL tested by HCM-2.0 were 1:100 diluted and retested. Quantitative values were fitted to a third order polynomial (M = 0.118303 + 1.07503 x V+ 0.0112128 x V(2) - 0.0055504 x V(3); M...HCM-2.0, V...bDNA-3.0, both log IU/mL) showing progressive nonlinearity of HCM-2.0 above 100 000 IU/mL but better clinical sensitivity with respect to bDNA-3.0. Dilution lead to a gain of at least a factor of 2.7 and thus, overestimation compared with bDNA-3.0. Deviation from linearity and overestimation upon dilution by HCM-2.0 are similar with HCV genotype 4, compared with other HCV genotypes. Differences in test performance were not detected for subtypes but for individual patients possibly related to specific quasi-species patterns. The interpretation of viral kinetic data becomes difficult due to overestimation upon dilution of baseline values by HCM-2.0.
authors.affiliation: Department of Internal Medicine IV, Gastroenterology and Hepatology, Vienna Medical University, Vienna, Austria.
authors.forename: W
authors.initials: W
authors.lastname: Jessner
authors.forename: T
authors.initials: T
authors.lastname: Watkins-Riedel
authors.forename: C
authors.initials: C
authors.lastname: Müller
authors.forename: E
authors.initials: E
authors.lastname: Formann
authors.forename: M
authors.initials: M
authors.lastname: Gschwantler
authors.forename: P
authors.initials: P
authors.lastname: Ferenci
mesh_terms: D005838:Genotype; D006515:Hepatitis B virus / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000097:blood / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000627:therapeutic use; D011092:Polyethylene Glycols; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000097:blood* / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D018709:Statistics, Nonparametric; D019562:Viral Load / Q000379:methods; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011092:Polyethylene Glycols; D012367:RNA, Viral; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; C417083:peginterferon alfa-2b