Photodynamic inactivation of herpesvirus hominins by methylene blue (38524).

Methylene blue, in a concentraion of 10-5M was virostatic in the presence of light but not in the dark for 31 of 37 strains of fresh isolates of herpesvirus hominis. Resistance to the dye developed during treatment. This photodynamic pattern was almost identical to that of neutral red which produced an identical effect. This was not ture for proflavine which was active in the dark in many instances. Cross insensitivity between proflavine and methylene blue was not observed.