Dubey J P
Parasite Biology and Epidemiology Laboratory, Agricultural Research Service, Beltsville, Maryland 20705-2350, USA.
J Parasitol. 1995 Jun;81(3):410-5.
Cats that have shed Toxoplasma gondii oocysts are considered to be immune to reshedding of oocysts. To investigate if this immunity persists in cats for 6 yr, 12 4-6-mo-old cats without T. gondii antibodies were inoculated orally with tissue cysts of the ME-49 strain (6 cats) and the TS-2 strain (6 cats) of T. gondii. All of them shed > or = 20 million oocysts between 4 and 13 days after feeding tissue cysts. Two cats became ill between 11 and 13 days after primary infection; 1 died on the 13th day, and the other had to be killed on the 11th day because of generalized acute toxoplasmosis. Toxoplasma gondii oocysts were not found on the hair of 10 cats examined 7 days after cats had shed millions of oocysts. On day 39 after primary infection, 5 cats (2 infected with the ME-49 strain and 3 infected with the TS-2 strain) were challenged orally with tissue cysts of the ME-49 strain. None of the challenged cats shed oocysts. One cat died due to causes unrelated to toxoplasmosis. Seventy-seven months after primary infection, the remaining 9 cats were challenged orally with tissue cysts of the P89 strain of T. gondii. Four of these 9 cats re-shed T. gondii oocysts; 3 of them had been challenged also at 39 days after primary infection. Two control cats housed together with chronically infected cats for 6 yr remained seronegative for T. gondii; both of these shed oocysts after challenge with the P89 strain.
已排出刚地弓形虫卵囊的猫被认为对再次排出卵囊具有免疫力。为了研究这种免疫力在猫体内是否能持续6年，将12只4至6月龄且无刚地弓形虫抗体的猫经口接种刚地弓形虫ME - 49株（6只猫）和TS - 2株（6只猫）的组织包囊。在喂食组织包囊后的4至13天内，所有猫排出的卵囊均≥2000万个。2只猫在初次感染后的11至13天发病；1只在第13天死亡，另一只因全身性急性弓形虫病于第11天不得不被处死。在猫排出数百万个卵囊7天后，对10只猫的毛发进行检查，未发现刚地弓形虫卵囊。在初次感染后的第39天，5只猫（2只感染ME - 49株，3只感染TS - 2株）经口用ME - 49株的组织包囊进行攻击。所有受攻击的猫均未排出卵囊。1只猫因与弓形虫病无关的原因死亡。初次感染77个月后，其余9只猫经口用刚地弓形虫P89株的组织包囊进行攻击。这9只猫中有4只再次排出刚地弓形虫卵囊；其中3只在初次感染后的第39天也受到了攻击。与慢性感染猫共同饲养6年的2只对照猫对刚地弓形虫仍呈血清阴性；这2只猫在用P89株攻击后均排出了卵囊。
