Inherent Photosensitivity of Herpes Virus and Other Enveloped Viruses

Except for herpes virus, a number of enveloped viruses have previously been reported to be sensitive to white light in the absence of photoreactive dyes. We have shown that herpes virus, like measles, Sindbis and vesicular stomatitis viruses, can also be rendered photosensitive if the virions are removed from the protective effects of organic compounds contained in the virus harvest. Under the very same conditions, non-enveloped viruses (vaccinia, polio and adenoviruses) are completely photoresistant. The photosensitivity of enveloped viruses can be enhanced by the presence of salts or increased pH values. Enveloped viruses are photosensitive even when replicated in cells grown and maintained in the absence of serum and riboflavin. Human herpes virus strains obtained from herpetic lesions and never passaged in cultures were also readily inactivated by white light. Experiments with monochromatic light showed the 425 nm. wavelength to be most effective in inactivating the virus. The virus envelope behaves like a functional membrane, since neutral red, which is taken up only by living cells, markedly increases the photosensitivity of enveloped viruses, but has no effect on naked viruses.