Lindsay D S, Dubey J P, Blagburn B L, Toivio-Kinnucan M
Department of Pathobiology, College of Veterinary Medicine, Auburn University, Alabama 36849-5519.
J Parasitol. 1991 Feb;77(1):126-32.
Tissue cyst formation by a goat isolate (GT-1) of Toxoplasma gondii was examined in bovine monocyte, human fetal lung, and Madin-Darby bovine kidney cell cultures. Transmission electron microscopy (TEM) and cat feeding studies indicated that tissue cysts were present in all 3 cell lines examined. Tissue cysts were first seen 3 days postinoculation (PI) using TEM. Standard cell culture procedures were used and no additional condition was needed to induce tissue cyst formation. Cats fed cell cultures excreted T. gondii oocysts in their feces 5-7 days PI. These oocysts caused lethal infections in mice. Tissue cysts were produced in cell cultures regardless if the initiating inoculum consisted of bradyzoites, sporozoites, or a mixture of bradyzoites and tachyzoites. Tissue cyst formation has been followed through 40 subpassages of infected cells. By TEM tissue cysts still were present after 40 passages, but when 40th-passaged cultures were fed to cats, oocytsts were not excreted. This indicates that the parasite had become oocystless after repeated passage in vitro.
在牛单核细胞、人胎儿肺细胞和马迪达比牛肾细胞培养物中检测了刚地弓形虫山羊分离株（GT-1）形成组织囊肿的情况。透射电子显微镜（TEM）检查和猫喂食研究表明，在所检测的所有3种细胞系中均存在组织囊肿。使用TEM在接种后3天首次观察到组织囊肿。采用标准细胞培养程序，无需额外条件即可诱导组织囊肿形成。喂食细胞培养物的猫在接种后5至7天粪便中排出刚地弓形虫卵囊。这些卵囊在小鼠中引起致死性感染。无论起始接种物是缓殖子、子孢子还是缓殖子与速殖子的混合物，细胞培养物中均会产生组织囊肿。已对感染细胞进行了40次传代以追踪组织囊肿的形成。通过TEM观察，传代40次后仍存在组织囊肿，但将第40代培养物喂给猫后，未排出卵囊。这表明该寄生虫在体外反复传代后已变为无卵囊状态。
