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目的观察流行我国的刚地弓形虫(Toxoplasma gondii)主要基因型China 1成囊株在感染小鼠体内的动态分布和包囊形成。方法采自武汉的猫源性刚地弓形虫株(TgCtwh1,基因型为China 1,即ToxoDB#9)包囊50个(约含1×104个缓殖子)经口感染SPF级CD1雌性小鼠50只,于感染后第2、4、7、10、14、21、35、50和72天,分别大体观察小鼠健康状况并测定体重;颈椎脱臼法处死小鼠,脑组织压片观察弓形虫包囊形成时间,计算成囊率,测量包囊直径;荧光定量PCR和组织接种方法检测弓形虫在血液、心、肝、脑和淋巴结组织中的动态分布。结果实验小鼠感染后第7天体重减轻(3.650±0.252)g;第10天[(1.730±0.017)g]与第14天体重差值[(-0.390±0.554)g]比较,有统计学意义(P<0.05)。感染后第21天,在脑组织中查获包囊,成囊率为80%,直径为20～40μm;至感染后第35天,小鼠成囊率增为100%,包囊直径为50～60μm。感染后第2天,TgCtwh1虫体即出现在血液、心、肝和淋巴结组织中,拷贝数分别为3.510±0.152、4.100±0.198、4.220±0.209和4.960±0.052,感染后第4天见于脑组织(3.800±0.154);血液中的虫体在第7天达峰值(5.240±0.115),随后逐渐下降,至第35天消失;心和脑组织中的虫体分别于第14天和第10天达峰值后(5.640±0.214和5.790±0.060)维持相对稳定的水平;肝和淋巴组织中的虫体分别于第7天和第10天达峰值(5.310±0.038和6.200±0.152),此后虫体逐渐减少,至第50天转阴。结论流行中国的弓形虫China 1基因型成囊株在感染小鼠体内虫血症可持续至少21 d,感染后第21天首次在小鼠脑组织内检测到包囊。
OBJECTIVE To observe the dynamic distribution and cyst formation of China 1 Toxoplasma gondii, a major genotype of Toxoplasma gondii, infected in mice. Methods Fifty (containing about 1 × 104 bradyzoites) were en bloced into SPF-like CD1 female mice from TgCtwh1 strain of GenBank (China ToxoDB # 9) 50 mice were sacrificed on the 2nd, 4th, 7th, 10th, 14th, 21st, 35th, 50th and 72th day after infection respectively. The mice were generally observed their health status and body weight. The mice were sacrificed by cervical dislocation, Toxoplasma cyst formation time was calculated, cyst formation rate was calculated, and the cyst diameter was measured. The dynamic distribution of Toxoplasma gondii in blood, heart, liver, brain and lymph node tissues was detected by quantitative PCR and tissue inoculation. Results The body weight of mice in experimental group was 3.650 ± 0.252 g on the 7th day after infection. Compared with the difference of body weight on the 14th day [(1.730 ± 0.017) g] on the 10th day [(-0.390 ± 0.554) g] Significance (P <0.05). On the 21st day after infection, the cysts were seized in the brain tissue. The rate of cyst formation was 80% and the diameter was 20 ~ 40μm. At the 35th day after infection, the cyst formation rate of the mice increased to 100% and the cyst diameter was 50 ~ 60 μm. On the second day after infection, TgCtwh1 was found in blood, heart, liver and lymph node tissues with copy numbers of 3.510 ± 0.152, 4.100 ± 0.198, 4.220 ± 0.209 and 4.960 ± 0.052, respectively. The fourth day after infection, (3.800 ± 0.154). The number of parasites in blood reached a peak on the seventh day (5.240 ± 0.115), then decreased gradually and disappeared on the 35th day. The parasites in the heart and brain tissue were on the 14th and 10th days (5.640 ± 0.214 and 5.790 ± 0.060), respectively. The number of parasites in liver and lymphoid tissues peaked at day 7 and day 10 (5.310 ± 0.038 and 6.200 ± 0.152 respectively) Gradually reduced to the first 50 days negative. Conclusion The Chinese cysticercosis of China Toxoplasma gondii China 1 in the infected mice could be sustained for at least 21 days. The cysts were detected in the brain of mice for the first time on the 21st day after infection.