title: Hepatitis C virus RNA quantitation in venous and capillary small-volume whole-blood samples.
abstract: Quantitation of hepatitis C virus (HCV) RNA in plasma and serum samples is a costly procedure in both time and reagents. Additionally, cell-associated viral RNA may not be detected. This study evaluated the accuracy of HCV RNA quantitation in small-volume whole-blood (WB) samples, which would be appropriate for point-of-care diagnostic devices. HCV RNA was extracted from 222 clinical plasma and WB samples of 82 patients with chronic hepatitis C by a specific locked nucleic acid-mediated capture method and quantified by real-time reverse transcription-PCR. The results were compared to the reference plasma viral load determined with the COBAS AmpliPrep/TaqMan (CAP/CTM) HCV test. This assay had an analytical sensitivity of 9 IU per 10-microl sample (95% limit of detection [95% LOD]), a linearity range of 500 to 5 x 10(6) IU/ml, and was accurate in testing 10 HCV subtypes (<0.22 log10 unit) in plasma. The assay was matrix equivalent for plasma and WB samples (coefficient of determination [R2] of 0.943) and had a specificity of 100% (n = 20) in WB samples. The HCV RNA concentration in clinical WB samples exceeded the estimated hematocrit-corrected plasma viral loads by 0.22 log10 unit, but absolute quantitation results in plasma and WB samples were identical (95% confidence interval, -0.06 to 0.04 log10 unit). The sensitivity in WB samples was 100% (n = 141) for plasma concentrations above the 95% LOD. Quantitation results in 10-microl WB samples correlated linearly with the CAP/CTM HCV plasma test results (R2 = 0.919; n = 140) and did not differ between capillary and venous samples (R2 = 0.960; n = 40). This study shows that HCV RNA quantitation in 10-microl WB samples is appropriate for monitoring viral loads of >900 IU/ml, although the use of WB does not increase the diagnostic sensitivity.
authors.affiliation: Division of Gastroenterology, Hepatology and Infectious Disease, Department of Internal Medicine II, Friedrich Schiller University, Jena University Hospital, Jena, Germany. tony.bruns@med.uni-jena.de
authors.forename: Tony
authors.initials: T
authors.lastname: Bruns
authors.forename: Katrin
authors.initials: K
authors.lastname: Steinmetzer
authors.forename: Eugen
authors.initials: E
authors.lastname: Ermantraut
authors.forename: Andreas
authors.initials: A
authors.lastname: Stallmach
mesh_terms: D001769:Blood / Q000821:virology; D002196:Capillaries / Q000821:virology; D016174:Hepacivirus / Q000302:isolation & purification*; D019698:Hepatitis C, Chronic / Q000821:virology; D006801:Humans; D012367:RNA, Viral / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D019562:Viral Load / Q000379:methods*
chemical_list: D012367:RNA, Viral
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