DIRECT-DETECTION OF HEPATITIS-C VIRUS (HCV) RNA FROM WHOLE-BLOOD, ANDCOMPARISON WITH HCV RNA IN PLASMA AND PERIPHERAL-BLOOD MONONUCLEAR-CELLS

Hepatitis C virus (HCV) requires reverse transcriptase-polymerase chai n reaction (RT-PCR) or branched DNA signal amplification assays to be detected in patient samples. Although conventional methods of RNA isol ation are employed for samples of serum, plasma, and peripheral blood mononuclear cells (PBMCs), whole blood is generally considered an unsu itable source of RNA because of abundant RNases and polymerase inhibit ors. Using a cationic surfactant, Catrimox-14, we adapted a procedure for RNA isolation from whole blood, plasma, and PBMCs that yields RNA template suitable for HCV RT-PCR. RNA isolation required less than 2 h r, and HCV sequences were easily detected in sample volumes of 50 mu l whole blood or plasma, and in less than 1 x 10(4) PBMC. Following the addition of blood to Catrimox, HCV RNA was stable in the mixture when incubated for at least 7 days at room temperature prior to RNA extrac tion. Comparison of whole blood HCV RNA and plasma HCV RNA from indivi duals with chronic hepatitis suggests that HCV RNA can be more reliabl y detected in whole blood. Three of 15 HCV antibody positive patients (20%) had HCV RNA present in whole blood but simultaneously obtained p lasma samples were negative. Two of five HCV antibody negative individ uals with chronic hepatitis contained HCV RNA in whole blood, yet one of these patient's plasma was negative for viral RNA. The Catrimox-14 method of RNA purification is useful for detecting HCV RNA in whole bl ood and blood subfractions, and provides a practical method of measuri ng plasma and PBMC HCV RNA from clinical specimens. (C) 1995 Wiley-Lis s, Inc.