Development of a Therapeutic Agent Based on Escherichia coli, Assessment of Harmlessness and Antiradiation Activity

The development and assessment of the safety and antiradiation activity of a therapeutic agent based on a culture of Escherichia coli strains PL-6 and KV-1 are presented. To obtain the antiradiation agent, the causative agent of colibacillosis was grown in meat-peptone broth in a thermostat at a temperature of 37°C for three days. The grown suspension was centrifuged at 3000 rpm for 50 min, and the supernatant was decanted. The sediment was brought to one billion cm³ with distilled water. Smears were prepared from the cultures grown and stained according to Gram to determine the purity and species of the culture grown. The prepared suspension was poured into sterile vials of 10, 50, or 100 cm³, sealed with rubber stoppers, and rolled with aluminum caps. They were labeled with an indication of the strain, radiation dose, and date. Irradiation of the microbial material was carried out on the Issledovatel γ-installation, with a ⁶⁰Co source, an absorbed dose rate of 1.028 Gy/s, in the ranges of absorbed doses from 7.5 to 30.0 kGy with interdose intervals of 2.5 and 5.0 kGy. The degree of inactivation of γ-irradiated E. coli cultures was determined by seeding them on meat-peptone agar and thermostatting for 168 h, recording the presence or absence of microorganism growth. Studies have established that the timing and degree of growth of irradiated E. coli cultures of the PL-6 and KV-1 strains are directly dependent on the radiation dose; their complete inactivation occurs with irradiation at a dose of 25.0 kGy. Further studies have shown that the developed biopreparation obtained on the basis of E. coli is sterile, areactogenic, nontoxic, and harmless. The mechanism of formation of radioresistance of the organism against the background of application of antiradiation agents based on the E. coli strains PL-6 and KV-1 consisted in restoration of the hematological, biochemical, and immune parameters, which contributed to preservation of 66.7 to 83.3% of lethally irradiated animals.