TABLE 1.

Characteristics of the purified C. parvum oocysts purchased from three different suppliers

Supplier	Strain	Supplier's lot no.	Purification method	50% Infective dose in mice (supplier's data)	Antibiotic solution used for storage	% Infectivity in cell culture (n)a
Pleasant Hill Farm	Iowa	99-23, 00-3, 00-11	Ethyl ether extraction, centrifugation, and a one-step sucrose gradient	NRb	PBS–penicillin (20 U/ml)–streptomycin (20 μg/ml)	1.48 ± 1.18 (7)
Sterling Parasitology Laboratory	Iowa	00619-25	Discontinuous sucrose gradients followed by cesium chloride gradients	121	Deionized water–penicillin (100 U/ml)–gentamicin (100 μg/ml)–0.01% Tween 20	2.31 ± 1.94 (2)
University of Alberta	Iowa	CP-020900-1	Sucrose flotation and cesium chloride gradient ultracentrifugation	103	Deionized water–penicillin (100 U/ml)–gentamicin (100 μg/ml)–streptomycin (100 μg/ml)–0.1% Tween 20	7.49 ± 2.11 (2)

^aResults are means and standard deviations. 

^bNR, not reported.