Photodynamic inactivation of newcastle disease virus with acridine orange.

Newcastle disease virus in allantoamnionic fluid was photosensitized with acridine orange, and then photodynamically inactivated. The inactivation rate was directly proportional to light intensity and to dye concentrations up to a level of approximately 100 to 200 mug/ml. Inactivation occurred at approximately an exponential rate for the first 4.5 log(10) units of virus, and then continued at a decreasing rate.