Further Observations on the Growth of Toxoplasma gondii in Roller Tube Cultures of Mouse and Primate Tissues

Abstract

The RH strain of T. gondii was propagated for 23 serial passages and a 2d strain for 13 serial passages in roller cultures of mouse embryonic tissues. Prolonged in vitro cultivation of the organism did not significantly alter its infectivity as measured in vivo and in vitro. The general sequence of multiplication of T. gondii and of the appearance of the specific cytopathic effects in roller cultures of mouse embryonic tissues was relatively constant, but failure to renew the nutrient medium at intervals reduced the number of organisms produced in culture, and the introduction of minimal inocula delayed their appearance by several days. Further experiments showed that: (1) T. gondii could be found intracellularly within 6 hours after inoculation; (2) during in vitro cultivation the organism probably multiplied intracellularly by binary fission; (3) Toxoplasma proliferated both in epithelial and fibroblastic cell types; and (4) all cells in inoculated cultures were ultimately destroyed. The elaboration of a stable soluble toxin by the organism in culture was not demonstrated. A strain of T. gondii propagated in cultures of mouse embryonic tissues retained its capacity to multiply in vitro within cells derived from various human tissues and within cells originating from rhesus testicular tissues.