Limited stability of Hepatitis B virus RNA in plasma and serum

Pregenomic hepatitis B virus RNA (HBV pgRNA) is a potential biomarker in the management of HBV infected patients. However, prior to the use in routine clinical practice potential confounders of test results need to be identified. This study investigates the stability of HBV pgRNA under various storage conditions. HBV-RNA level of 26 HBV patients were determined using the Roche cobas® 6800/8800 investigational HBV-RNA assay. Plasma and serum were stored for 6,48,169 h at 4,25 and 42 °C, respectively. Additionally, 10 serum and plasma samples underwent 4 or 11 cycles of freezing (-80 °C) and thawing (25 °C). A significant decline in mean pgRNA concentration compared to baseline was observed after storage for 48 h at 25 °C as well as after 6 h of storage at 42 °C. Accordingly, sub-analyses of predefined pgRNA baseline concentrations (≤ 10 cp/mL, > 10-100 cp/ml, > 100 cp/mL) revealed significant changes in pgRNA level after storage at 25 and 42 °C. No effect of freezing and thawing on pgRNA level was observed. A qualitative detection of HBV pgRNA is feasible in samples with > 100 cp/mL up to 48 h under storage temperatures of 4-42 °C. For most stable quantitative HBV pgRNA values storage at 4 °C should be preferred.