The impact of storage time on HCV RNA quantitative detection in serum samples by TaqMan real-time PCR

Information on the concentration of hepatitis C virus (HCV) RNA is useful for patient management, including assessing treatment initiation and treatment response, and monitoring follow-up. Previous studies have reported that poor sample processing and storage conditions might influence the stability of HCV RNA, and hence its detectability. We analyzed 30 patients known to be positive with high/intermediate/low HCV RNA load, and kept their serum samples in storage at 4°C for 0, 1, 2, 3, 7, 14, 21 and 28 days. Quantitative detection of HCV RNA was performed by TaqMan real-time PCR. The results showed that no decrease in the concentration of HCV RNA was detected over the 14 days period at 4°C (P > 0.05) for the high and intermediate HCV RNA load groups. However, after 21 and 28 days of storage, the mean viral loads in both groups differed significantly from those at Day 0 (P > 0.005). For the low HCV RNA load group, an important loss of HCV RNA concentration was observed when the serums were stored at 4°C after 14 days, 21 days and 28 days (P < 0.001). These data demonstrated that serum samples with HCV RNA levels up to 104 IU/ml can be stored at 4°C for 14 days, and that lower than 104 IU/ml can be performed for up to only 7 days when the samples are stored at 4°C.