Nutrition of the Host and Natural Resistance to Infection

Abstract

The double strain inoculation (DSI) method of testing for natural resistance to infection has been examined in the instance of mouse salmonellosis. The DSI method has been found capable of detecting differences in natural resistance due to genetic as well as nutritional causes. A difference in response to Salmonella infection was found for the first time between the two "susceptible" inbred mouse strains, BSVR and BSVS. Whereas BSVS mice for the most part survived an intraperitoneal injection of 103 "avirulent" S. typhimurium, BSVR mice all succumbed. The relationship of the DSI test to the usual single infection test has been discussed and it is suggested that such single infection tests are special cases of the DSI test, since they involve a heterogeneous bacterial population which can be considered as a mixture of cultures of differing virulence and in which, by a single injection, the usual time interval between the two injections of the DSI method has been reduced to 0.

Some Physiopathological Parameters of Natural Resistance to Infection in Murine Salmonellosis

“…In the present investigation we have elected the genetic arrangement of host differences in survivorship. Now, although the physiological mechanism responsible for such genetically arranged differences is unknown it has been shown that these very survivorship differences are operationally dependent on the genetic structure of the pathogen population, demanding a genetic heterogeneity in terms of virulence (6). It is still moot whether this operational necessity can be generalized to embrace other infectious diseases, but in the present concern with mouse salmonellosis we have felt obliged to retain this prescription and have employed the double strain inoculation infection test (7) as a precise means of providing the appropriate pathogen populational structure.…”