Study on the effects of heat and ultraviolet fight radiation on hepatitis C virus JFH-1 strain inactivation

Abstract

Objective To investigate the inactivating effect of heat and ultraviolet(UV) light on HCV JFH-1 strain using the cell culture system. Methods The HCV JFH-1 virus stock, with an initial titer of 2.5 × 104 FFU/ml, was exposed in 56℃ water bath or to UV light for varying durations of time for explo-ring their inactivating effects on the virus. The kinetics of virus titer reduction was determined by an indirect immuno-fluorescence assay (IFA). If the cells infected with the exposed virus stock were IFA negative after three blind passages, the virus stock was considered to be inactivated completely. Results After incubation of the HCV JFH-1 virus stock (2.5 × 104 FFU/ml)in 56℃ water bath for 10 min, 20 min and 30 min, the virus titers were reduced to 1.6 × 103 FFU/ml, 3.1 × 102 FFU/ml and 3.3 × 10 FFU/ml, respectively. The exposure of the virus stock to UV light (wavelength 253.7 nm, intensity ≥60 μW/cm2, 30 cm below the UV lamp) for 15 s, 30 s and 45 s resulted in virus fiter reduction to 1.0 × 103 FFU/ml, 1.1 × 102 FFU/ml and 2.7 × 10 FFU/ml, respectively. After 40 min incubation of the virus stock at 56℃, or 1 min exposure to UV light (wavelength 253.7 nm, intensity ≥60 μW/cm2) the virus infectious titer was reduced below the detection limit of IFA, and the IFA was still negative even after three blind passages, indicating that the virus was inactivated completely. Conclusion HCV is sensitive to heat and UV light treatment. For HCV JFH-1 virus stock containing 2.5 × 104 FFU/ml virus, heat treatment at 56℃ for 40 min, or UV light expo-sure at an intensity of ≥60 μW/cm2 for 1 min, resulting in complete virus inactivation. Key words: Hepatitis C virus (HCV) : Cell culture: Infectious titer: Inactivation