EXPERIMENTAL STUDIES ON INFECTION AND IMMUNITY IN LEPTOSPIROSIS : III. THE USE OF MICE FOR ESTIMATION OF LEPTOSPIRAE

Abstract

Basic studies on the use of the mice from dd strain for the estimation leptospirae, especially those in tissues and organs, were carried out. The results obtained are summarized as follows: 1) The preliminary agglutination-lysis test is applicable to the small amount of the blood obtained from the tail of each mouse. By this procedure, the use of intact mice is made possible for experiments on leptospirosis. 2) A serological survey of leptospirosis was carried out on mice from dd strain, using 5 antigens, including L. icterohaemorrhagiae, and L. ballum. Not one of all the 3, 038 mice examined, was positive. 3) The susceptibility of the mice to leptospirae was examined by inoculation with a small number of leptospiral cells. A marked rise in the agglutination-lysis titer, and the detection of leptospirae in the kidneys, were demonstrable even in the mice inoculated with a very small number of leptospiral cells. ID₅₀ of strain TR-1 (L. icterohaemorrhagiae) for mice, was calculated at 11.2±1.5, and of strain Saeki (L. autumnalis), at 1.9. 4) Experimental examinations were carried out on the cage infection of leptospirosis in mice, with negative results. 5) In view of the high susceptibility of the mice to leptospirae, estimation of leptospirae was considered to be possible by their use. A formula developed for calculating the number of leptospiral cells in tissues and organs, was presented.