Effect of polyions, Ca++, and enzymes on penetration of cultured cells by Eimeria meleagrimitis sporozoites.

Cell cultures from kidneys of turkeys were treated with four cations, two polyamions, or two proteolytic enzymes and then inoculated with Eimeria meleagrimitis sporzoites. After a 20-min incubation, cultures treated with three of the cations (poly-L-histidine, poly-L-lysine, or Ca++) or with chymotrypsin contained significantly fewer intracellular sporozoites than did the untreated control cultures. Increases in the concentration of poly-L-histidine or chymotrypsin produced linear decreases in the numbers of sporozoites. In contrast, after a 2-hr incubation, treated and control cultures contained the same numbers of intracellular sporozoites. Treatment of cell cultures with the fourth cation (DEAE-dextran), the two polyanions (heparin or dextran sulfate), or trypsin did not significantly affect the numbers of sporozoites after either 20-min or 2-hr incubation. Sporozoites that were pretreated with poly-L-histidine, Ca++, or chymotrypsin for 20 min and then inoculated into untreated cultures were found intracellularly in the same numbers as were untreated sporozoites. Apparently, the reduced number of intracellular sporozoites in treated cultures resulted from interactions between the treatment substances and the host cells, and was not caused by immobilization of the parasite.