UV Disinfection of Adenovirus: Present State of the Research and Future Directions

Adenoviruses are nonenveloped, double-stranded DNA viruses that infect humans, causing dysentery and respiratory infection. Adenovirus has become a focus of the water treatment community because of its apparent resistance to ultraviolet (UV) disinfection and is the basis for stringent new regulations from the U.S. Environmental Protection Agency regarding UV disinfection of all viruses. Most of the work done so far, however, has involved the use of monochromatic (254 nm) low-pressure UV sources and assay of viral inactivation in cell culture models. Adenovirus is most likely not truly resistant to UV damage but is instead damaged and then repaired in host cells during cell culture infectivity assays. Recent research has shown that newer, polychromatic UV sources are more effective than monochromatic low-pressure UV at inactivating adenovirus. The potential for viral DNA repair in cell culture necessitates the use of alternative assay methods to measure UV disinfection efficiency: these include molecular biology and animal infectivity assays. Research to help clarify the effects of UV on adenovirus should therefore address two major issues not addressed in most studies published so far: the nature of (a) the UV source used to inactivate the virus and (b) the assays used to determine inactivation and characterize viral response. In this review, the authors discuss previous work on UV inactivation of adenovirus as well as present and ongoing work designed to address these two issues.