Inactivation of Viruses by the Photodynamic Action of Toluidine Blue

Abstract

In a study of the rates of inactivation of 11 different viruses by the photodynamic action of toluidine blue and visible light, a wide range of variation was encountered. Relative velocity constants, determined under standard conditions of dye concentration and light intensity, ranged from 1.0 for T3 coliphage and vaccinia virus to less than 0.001 for poliovirus and Coxsackie B2 and appeared to correspond at least approximately with accepted taxonomic groupings. According to a hypothetical mechanism for this reaction, the dye combines at sites essential for infectivity, providing “marked targets” for the destructive action of the light energy. The dye then acts as a photosensitizer by absorbing light of specific quantum energy and transferring the energy increment to the virus particle at the site of combination.