Wang Lin, Huo Xing-Xing, Chen Zhao-Wu, Chen He, Yu Li, Song Xiao-Rong, Faustina Halm-Lai, Luo Qing-Li, Shen Ji-Long
Department of Parasitology, Provincial Laboratory of Microbiology & Parasitology and Key Laboratory of Zoonoses, Anhui Medical University, Hefei 230032, China.
Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi. 2012 Jun 30;30(3):179-83.
To determine the kinetics of infection and cyst formation in CD1 mice following oral infection with cyst-forming Chinese isolate of Toxoplasma gondii TgCtwh1(genotype China 1, ToxoDB#9).
50 CD1 female mice were obtained from specific pathogen-free (SPF) mouse colony in the Vital River Laboratories (VRL), Beijing. Mice were randomly divided into 10 groups each with 5 mice. All mice but control were peroral gavage infected with 50 cysts (1x10(4) bradyzoites) of TgCtwh1 isolate of T. gondii isolated from Wuhan, China. Cysts were isolated from the entire brain of mice infected with TgCtwh1 by density gradient centrifugation over Fycoll-paque plus. Animals were orally inoculated with cysts on day zero, and peripheral blood, lymph nodes, heart, liver, and brain of infected mice were collected on days 2, 4, 7, 10, 14, 21, 35, 50, and 72 post infection. Five mice were sacrificed by cervical dislocation under anesthesia at each time of collection, and the kinetic distribution was detected by fluorescence quantitative PCR and tissue inoculation into fresh mice. The cyst formation at various intervals after infection was also observed, as was the number of the cysts in brains and the cyst-forming rate.
The body weight of the mice lessened (3.650 +/- 0.252)g post oral infection on day 7, and the weight was progressively decreased between day 10 [(1.730 +/- 0.017)g] and day 14 [(-0.390 +/- 0.554) g] after infection (P<0.05). In the brain tissue, cysts were first observed on day 21 post oral infection and the cyst-forming rate was 80%, and the average diameter of cysts was 20-40 microm. While on day 35 after infection, the cysts were formed in all infected mice(cyst-forming rate was 100%) and the average diameter was 50-60 microm. In chronic infection, DNA copies of parasites were first detected in blood, heart, liver and lymph node at 3.51 +/- 0.152, 4.100 +/- 0.198, 4.220 +/- 0.209 and 4.960 +/- 0.052 respectively on day 2, then in the brain on day 4 (3.800 +/- 0.154). During the early days of infection, the parasite burden in blood was progressively increased until days 7 (5.240 +/- 0.115) then gradually decreased and become undetectable on day 35. The burden of T. gondii in the heart and brain tissues increased significantly and reached their maximum on day 14 (5.640 +/- 0.214) and day 10 (5.790 +/- 0.060), respectively, and remained a stable level thereafter. Liver and lymph tissues reached their maximum on day 7 (5.310 +/- 0.038) and day 10 (6.200 +/- 0.152), then gradually decreased and become undetectable on day 50.
The parasitemia in mice infected with T. gondii cyst-forming isolate lasts for 21 d at least, and cysts are detected in brain on day 21.
确定用形成包囊的中国弓形虫TgCtwh1分离株（基因型China 1，ToxoDB#9）经口感染CD1小鼠后感染及包囊形成的动力学。
从北京维通利华实验动物技术有限公司（VRL）的无特定病原体（SPF）小鼠种群中获取50只CD1雌性小鼠。将小鼠随机分为10组，每组5只。除对照组外，所有小鼠经口灌胃感染从中国武汉分离的50个TgCtwh1株弓形虫包囊（1×10⁴个缓殖子）。通过在Fycoll-paque plus上进行密度梯度离心从感染TgCtwh1的小鼠全脑中分离包囊。在第0天给动物经口接种包囊，在感染后第2、4、7、10、14、21、35、50和72天收集感染小鼠的外周血、淋巴结、心脏、肝脏和脑。每次收集时，在麻醉下通过颈椎脱臼处死5只小鼠，通过荧光定量PCR和接种到新鲜小鼠体内检测动力学分布。还观察了感染后不同时间间隔的包囊形成情况，以及脑中包囊数量和包囊形成率。
口服感染后第7天小鼠体重减轻（3.650±0.252）g，感染后第10天[(1.730±0.017)g]至第14天[(-0.390±0.554)g]体重逐渐下降（P<0.05）。在脑组织中，口服感染后第21天首次观察到包囊，包囊形成率为80%，包囊平均直径为20 - 40微米。而在感染后第35天，所有感染小鼠均形成包囊（包囊形成率为100%），平均直径为50 - 60微米。在慢性感染中，感染后第2天在血液、心脏、肝脏和淋巴结中首次检测到寄生虫DNA拷贝数分别为3.51±0.152、4.100±0.198、4.220±0.209和4.960±0.052，然后在第4天在脑中检测到（3.800±0.154）。在感染早期，血液中的寄生虫负荷逐渐增加直至第7天（5.240±0.115），然后逐渐下降，在第35天变得不可检测。弓形虫在心脏和脑组织中的负荷显著增加，分别在第14天（5.640±0.214）和第10天（5.790±0.060）达到最大值，此后保持稳定水平。肝脏和淋巴组织在第7天（5.310±0.038）和第10天（6.200±0.152）达到最大值，然后逐渐下降，在第50天变得不可检测。
感染弓形虫形成包囊分离株的小鼠的寄生虫血症至少持续21天，在第21天在脑中检测到包囊。
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