Comparative Observations on Virulence of Seven Strains in the Murine Leprosy Bacillus

Abstract

From the fact that this bacillus is present in a state of compatibility with the histiocyte in the host, it is suggested that the organism itself does not have a strong toxicity. In order to determine the virulence, therefore, the quantity of bacilli required to kill the host should not be taken as the index but evaluation should be based on the laproma development at the inoculation site.
A comparative study has been made on the virulence of the Kumamoto, Keishicho, Kurume-42, Fukuoka-1, Hawaiian, Douglas and Odessa strains.
Two strains of mouse with differing susceptibility, C3H (onset delayed but leproma large) and C57BL₆ (onset rapid but leproma small), were used. The strains of bacilli had been maintained for more than 10 generations in mice under the same conditions. Leproma emulsions of each strain were prepared, .
0.25ml of 10^-2-10^-3 diluted solution inoculated subcutaneously and the size of the leproma produced was measured up to 20 weeks. The animals were then sacrificed and the leproma weighed. The distribution of bacilli to the organs was also examined.
As can be seen in the table, no significant difference was noted between the 7 strains.