Assessment of viral disinfection by means of bacteriophage OX 174

A method was developed for evaluating the viricidal effectiveness of chemical disinfectants. The method uses the DNA bacteriophage phi X 174 (ATCC 13706-B1), whose host is Escherichia coli C (ATCC 13706-1), as the model virus. The bacteriophage has particles of icosahedral symmetry, 26 nm in diameter, and resembles animal entero- and parvoviruses by its resistance to physicochemical factors. Disinfection effectiveness was evaluated in suspension medium and on carriers of different materials that are disinfected in practice. The Horvath-Alföldi method on plexiglass panels containing 21 dishes of 40-mm diameter and 2-mm depth was used. A volume of 0.2 ml of phage suspension or one flat carrier 25 mm X 25 mm was put per panel dish and overlaid with 3 ml of dissolved soft agar medium containing at 37 degrees C, quantitatively as VE = log (No/Nd) in suspension tests and semiquantitatively on a 0-5 scale in tests on carrier materials. The viricidal effect of disinfectant-containing washing agents was tested on textile carriers during washing in an experimental washing machine. The method can be adjusted to evaluate the viricidal effectiveness of disinfection under different environmental conditions, e.g. in sanitary, agricultural, veterinary or food-industry facilities.