[Biological effects of gamma rays on Salmonella gallinarum and their use in controlling fowl typhoid].

The results are given of following up some biologic effects produced by gamma-rays on Salmonella gallinarum with a view of disclosing the possibilities of their use in the control of fowl typhoid. Used were strains of Salmonella gallinarum isolated from birds affected with acute typhoid. The possibility is stated of the detoxication of an endotoxin of Salmonella gallinarum parallel to the growing intensity of the gamma-rays (1 to 10 Mrad). It was found that the process of detoxication was better expressed in the irradiation of the bacterial cell in vivo. Rates of 20 Mrad were said to substantially modify the endotoxin, rendering it slightly toxic, it retaining its antigenic properties and haptene activity. The same modification could successfully be used as an allergen in the diagnosis of typhoid of birds when alive. It was also established that the use of sublethal rates of gamma-rays from 30 to 80 krad induced various morphologic and biochemical changes in Salmonella gallinarum. Of interest were likewise the studies of the R-strains and a histidine-dependent strain of Salmonella gallinarum which had retained their immunogenic properties.