Bacterial effect of accelerated electrons on several pathogens

Full text: Applied radiobiology assumes the use of results of fundamental studies of radiobiological phenomena which can serve as the basis for the development of certain technological processes. Radiation biotechnology (RBT) arises from applied radiobiology and is its natural sequel. RBT includes the development of the methods and techniques to use the energy of ionizing radiation in various areas of human activities including scientific research which is aimed at the production of biological medications which are useful for veterinary [1]. It is known that in order to obtain the vaccine for veterinary it is necessary to use physical, in particular, thermal and chemical effects. It was noted that in these processes the antigenic structure of bacterial cells which is responsible for creation of immunity is destroyed. The use of ionizing radiation as one of the factors of influence on bacteria gives the possibility to reduce the virulence to a minimum while preserving immunogenic properties of microorganism and not destroying its antigenic structure. The issue of simultaneous vaccination of the cubs of farm animals against several infectious diseases is important not only in theoretical but also in applied area since it determines the choice of strategy to increase the efficiency of preventive measures. Taking into account frequent cases of cubs' infection by pasteurellesis, salmonellosis and colibacterillesis in mono- and mixed forms, the radiation biotechnology to construct radio vaccines against infectious diseases was developed in laboratory of radiobiology of Research Institute of Veterinary of Uzbekistan (RIVU) [2]. Radiation biotechnology allows to produce highly effective mono-associated and polyvalent radio vaccines against the most widespread diseases of farm animals, especially the cubs. Using the mentioned radiation biotechnology, 'Associated radio vaccine against colibacterillesis and salmonellosis of small cattle' and Associated radio vaccine against colibacterillesis and salmonellosis of calves' were developed in RIVU. By widening the application field of developed radiation biotechnology the 'Polyvalent vaccine against pasteurellesis, salmonellosis and colibacterillesis of farm animals' was created in recent years. The mentioned radio vaccines were successfully tested in laboratory and working environment and are widely used in veterinary practice in the farms of the Republic of Uzbekistan [3].For further broadening of the possibility to use the radiation biotechnology and to enrich the native arsenal of veterinary bio medication, it is presently planned to conduct large-scale research on the use of accelerated electrons (AE) to obtain in perspective new preventive materials. Several results of the beginning stage of this research are given in the present report.The suspensions of pathogenic strains of pasteurellesis, salmonellosis and Escherichia Coli strains were exposed to irradiation by accelerated electrons of microtron MT-22C. Taking into account the slightly higher resistance of bacteria against irradiation by accelerated electrons as compared to gamma-irradiation, the doses from 400 to 1100 kRad were used. At this, the special attention was paid to control the distribution of linear density of the current in scanning of AE beam, the distribution of linear density of the current in perpendicular scanning of AE beam and the value of absorbed dose. The studies showed that at AE irradiation by 400 kRad dose the bacterial survival rate is about 10 %, at 500 kRad-2-3 %, 600 kRad- less than 1 %. At the dose of 800 kRad only isolated colonies of bacteria survived. At AE irradiation by 900 kRad- 1.1 MRad dose, there was no increase the growth of bacteria's number. Since these data were obtained at the multiple repetition of results, it can be supposed that the minimal absolute devitalizing AE irradiation dose of bacteria lies in the region 0.9-1.0 MRad. At this, some inter-species and even intra species peculiarities in the sensitivity of pasteurellesis, salmonellosis and Escherichia Coli strains were discovered. It was determined that salmonellosis and Escherichia Coli strains are more stable to AE irradiation than the strains of pasteurellesis. In the nearest perspective it is planned to work through all physical and biological irradiation parameters for these bacteria in order to develop radiation biotechnology (using A E) for designing the vaccines for veterinary. (author)