Higher yields and increased purity of in vitro grown toxoplasma gondii

An improved method for in vitro cultivation of Toxoplasma gondii is described. Commonly, confluent cell monolayers are infected with Toxoplasma; higher yields and an increased purity could be obtained instead when host cells were immediately infected after subculture: Depending on the initial parasite inoculum 2–3 fold increased multiplication rates were achieved and simultaneously the amount of host cell debris was reduced to 10–20 per cent compared to that deriving from infected cell monolayers. This may be ascribed to a facilitated invasion of host cells by Toxoplasma when the cell's glycocalyx is irritated by trypsinization and to a more far-reaching exploitation of young separated host cells in contrast to cells of monolayers. Moreover, the Toxoplasma trophozoites could be harvested from tissue culture already four days after infection without any change of medium, which makes the method very economical.