FACTORS AFFECTING M13-BACTERIOPHAGE INACTIVATION BY METHYLENE-BLUE PHOTOSENSITIZATION

We have investigated the factors that affect the virucidal activity of methylene blue (MB) photosensitization, The M13 bacteriophage was mor e rapidly inactivated at higher temperatures (6 degrees C < 24 degrees C < 38 degrees C). Rate constants for inactivation were 0.072, 0.139 and 0.260 (log(10) inactivation)/(J/cm(2)) at 6 degrees C, 24 degrees C and 38 degrees C, respectively, On the other hand, dye penetration i nto virus particles, which was monitored by the fluorescence of YOYO-1 , was unchanged with incubation temperature, These data suggest that t emperature dependency of M13 inactivation was due to factors other tha n dye permeability. The pH of the virus suspension also affected the r ate of M13 inactivation by MB. The M13 bacteriophage was inactivated f aster in basic suspensions and slower in acidic suspensions compared w ith neutral buffers, These results suggest that temperature and pH are factors that influence the extent of MB photosensitization, and hence , the control of these factors will be necessary for MB phototreatment of plasma products in transfusion medicine.