Photosensitization of T2 coliphage with toluidine blue.

The photodynamic action of dyes upon biological systems has been reviewed by Blum (1941). Inactivation of bacteriophage by this process has been studied by Clifton (1931), Perdrau and Todd (1933), Burnet (1933), Morales (1941), and Pacheco and Morales (1941). More recently, Welsh and Adams (1954) and Yamamoto (1956, 1958) investigated the kinetics of photodynamic inactivation of coliphage. In the course of preliminary experiments to determine the action spectrum for photodynamic inactivation of T2 coliphage with toluidine blue, we were unable to obtain reproducible velocity constants for the reaction. The variation was found to be related to the time of contact between dye and virus prior to irradiation. Upon further investigation it became evident that T2 phage differs from T3 in rate of uptake and tenacity of binding of this dye, indicating that these two phages differ in their permeability.