Abstract
In spite of several attempts to cultivate the virus of typhus fever by the method of tissue culture, it seems that such cultures could not be carried through repeated successive generations. The methods employed have been practically the same; viz., the cultivation of tissues (generally brain and spleen) from typhus infected guinea pigs in homologous plasma. Thus Kuczynski 1 found the virus of typhus fever virulent for 4-19 days, Krontowski and Hach 2 for 8 days, Wolbach and Schlesinger 3 for 20 days (28 days by transferring the same piece of tissue into fresh medium), and Rix 4 for 6 days. Recently Zinsser and Batchelder, 5 using tunica tissue from testicles of guinea pigs infected with Mexican typhus, prepared cultures which were virulent for one week. They were able to demonstrate rickettsias in great numbers in smears from such cultures.
The strain of typhus used in our studies, was isolated from a case in the southeastern United States by the Hygienic Laboratory in Washington, D. C. This strain is in all respects quite similar to the Mexican strain of Mooser. While not all of our attempts to establish strains by the methods to be described were successful, the following results were obtained in a number of experiments.
Employing the technic of Rivers, Haagen and Muckenfuss 6 for the cultivation of the viruses of vaccinia and herpes in tissue cultures of rabbit cornea in coagulated plasma, it was possible to carry the virus of typhus fever through at least 7 generations covering a period of 10 weeks. Pieces of normal guinea pig tunica (about 2 mm. square), soaked for a few minutes in a saline suspension of tunica scrapings from guinea pigs infected with typhus, were imbedded in wide tubes in a medium of guinea pig plasma coagulated by means of saline extracts of normal guinea pig spleen.
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