Effectiveness of physical inactivation methods of dengue virus: heat-versus UV-inactivation

Introduction Complete inactivation of virus is crucial before samples are manipulated outside of biological containment areas or general cleaning. There are several control methods that could decrease the risk from viral contamination on surfaces, which include chemical disinfectants, heating sterilisation, and ultraviolet germicidal irradiation depending on the nature and properties of the materials to be sterilised. To date, there are limited studies reporting the effectiveness of physical inactivation methods of dengue virus. Therefore, this study was designed to evaluate the effectiveness of two physical inactivation methods, which are heat- and ultraviolet-inactivation, against dengue virus. Material and methods All dengue virus serotypes were subjected to heat treatment at various temperatures and exposed to UV light (wavelength of 250-270 nm) at a distance of approximately 75 cm in a Class II Biosafety cabinet (ESCO) at room temperature. The effectiveness of inactivation methods was tested using viability testing on Vero cells and immunofluorescence assay. Results Dengue virus can be effectively inactivated by heat treatment at 56°C for at least 30 minutes or at higher temperature. On the other hand, the virus required 45 minutes or longer of ultraviolet light exposure at 75 cm distance from the source to be completely inactivated. Conclusion The results indicated that DENV can be effectively inactivated using high temperature, i.e. 56°C or above, and UV light irradiation. This result would serve as guidelines in proper decontamination and control of dengue virus in laboratory settings, provided proper conditions are met.