Sensitivity of Vi phages III to γ-radiation in the presence of cisplatin

In this study we determined Vi bacteriophage III sensitivity to native cisplatin, γ radiation (60Co) or to irradiated cisplatin, and checked the possibility of enhanced Vi bacteriophage III inactivation under combined exposure to cisplatin and γ radiation. We used highly purified phage suspensions in 0.9% NaCl solution or phosphate-buffered saline. Phage suspensions were titrated using a double agar layer method. Our study implies that survival of Vi bacteriophage III shows an exponential inverse correlation with cisplatin concentration in the incubation medium and the time of phage incubation in the presence of cisplatin. The use of irradiated cisplatin reduces phage survival in comparison with suspensions containing non-irradiated cisplatin. Irradiation of phage suspension with cisplatin causes a significant increase of phage inactivation in comparison with either treatment alone. Our results suggest that presence of cisplatin in irradiated medium enhances the radiobiological effect on Vi bacteriophages III.