McColgan C, Buxton D, Blewett D A
Animal Diseases Research Association, Moredun Research Institute, Edinburgh.
Vet Rec. 1988 Oct 29;123(18):467-70. doi: 10.1136/vr.123.18.467.
Fifty-nine ewes, seronegative to Toxoplasma gondii, were allocated to four groups which received 2000, 200, 20 or no M1 strain toxoplasma oocysts 56 days before mating. Fifty-one of them subsequently became pregnant and were challenged with 10,000 oocysts between 78 and 83 days of gestation. Infection with 2000 oocysts induced a pyrexia, seroconversion and protective immunity in all the recipient animals. Ewes that received either 20 or no oocysts before pregnancy were susceptible to subsequent challenge and severe fetal mortality occurred. In this study 200 oocysts was the threshold value for the induction of toxoplasma infection in sheep, although not all the ewes that seroconverted to this dose were protected against further challenge.
59只对刚地弓形虫血清学阴性的母羊被分为四组，在配种前56天分别接受2000、200、20个或不接受M1株弓形虫卵囊。其中51只随后怀孕，并在妊娠78至83天之间接受10000个卵囊的攻击。接受2000个卵囊感染的所有受体动物均出现发热、血清转化和保护性免疫。怀孕前接受20个或未接受卵囊的母羊易受随后的攻击，且发生严重的胎儿死亡。在本研究中，200个卵囊是诱导绵羊感染弓形虫的阈值，尽管并非所有对该剂量血清转化的母羊都能免受进一步攻击。
