Methylene blue-mediated photodynamic inactivation as a novel disinfectant of enterovirus 71

Abstract

We tested whether methylene blue, an inexpensive and safe photosensitizer, is feasible for photodynamic inactivation of enterovirus 71 (EV71) in the environment. By escalating light doses and photosensitizer concentrations, photoinactivation of EV71 and other enteroviruses was examined in vitro. Viral transmission in the environment was simulated with a neonatal mouse model in vivo. Possible mechanisms were analysed with alterations of viral DNA and proteins after treatments. Photodynamic inactivation of EV71 in suspensions occurred in a dose-dependent manner. The optimal condition for photoinactivating EV71 required a light dose of 200 J/cm(2) in the presence of methylene blue. This photodynamic condition was also able to inactivate other enteroviruses, including poliovirus 1 and coxsackieviruses A2, A3, A16 and B3. In an imitation environment, EV71 spread on a solid surface was inactivated by methylene blue-mediated photodynamic inactivation and prevented EV71 transmission to mice. Western blot and RT-PCR analysis indicated that both the viral proteins and the genome were disrupted after photodynamic inactivation. Methylene blue-mediated photodynamic inactivation may provide a novel way to eliminate environmentally contaminated sources of EV71 to prevent infection.