STAg联合ESA鼻内免疫小鼠对弓形虫垂直传播的阻断作用

观察弓形虫可溶性速殖子抗原（Soluble tachyzoite antigen,STAg）与排泄-分泌抗原（Excreted/secreted antigens,ESA）单独或联合鼻内免疫小鼠对弓形虫垂直传播的阻断作用。分别用PBS 20μL和STAg 20μg、ESA 20μg及联合抗原（STAg 10μg＋ESA 10μg）鼻内免疫BALB/c处女鼠2次,间隔2周。末次免疫后第13天处女鼠与雄鼠以2∶1同居。妊娠第8天用弓形虫速殖子（8000个/只）灌胃攻击所有孕鼠。妊娠第18天处死,计算活胎率,并测定孕鼠肝、胎盘和胎鼠脑组织弓形虫抗原和孕鼠脾组织内虫荷,同时测定孕鼠小肠冲洗液SIgA、血清IgG水平。结果表明,ESA组和联合抗原组活胎率显著高于PBS组,STAg组、ESA组和联合抗原组胎盘及胚胎感染率均低于PBS组,联合抗原组最低。孕鼠在弓形虫速殖子攻击后,PBS组明显出现竖毛、倦怠、腹部塌陷等异常表现,感染率为100%,死亡率为22.22%,而STAg组、ESA组和联合抗原组有轻微症状,感染率分别为85.71%、57.14%、57.14%,死亡率分别为16.67%、0%、0%。STAg组、ESA组和联合抗原组脾组织内虫荷均显著低于PBS组,减虫率分别为72.19%、72.29%、78.45%,ESA组和联合抗原组小肠冲洗液特异性SIgA均显著高于PBS组,联合抗原组最高,血清特异性IgG抗体水平差异不显著。由此可见,ESA单独或与STAg联合免疫可诱导孕鼠小肠液高水平SIgA,显著降低脾组织虫荷,显著提高胚胎存活率,表现出明显的垂直传播阻断的作用。

INTRANASAL VACCINATION WITH STAG AND ESA AGAINST VERTICAL TRANSMISSION OF TOXOPLASMA GONDII IN MICE

To observe the effect of intranasal vaccination with ESA, STAg and the combination against vertical transmission of Toxoplasma gondii in mice, forty BALB/c virginal mice were randomly divided into four groups. Mice were immunized with PBS 20 μL, STAg 20μg, ESA 20μg and combination of 10μg STAg and 10 μg ESA, respectively. All mice were immunized intranasally twice at the interval of 14 days. Females were mated with males on the 13^th day after the last immunization. The mice were orally infected with 8 000 tachyzoites of T. gondii RH strain on day 8 of gestation. On day 18 of gestation, the mice were killed and the infection rate, average live embryo rate and tachyzoites of their spleens were computed. The specific SIgA antibodies in intestinal washes and Serum IgG and the Toxoplasma antigen in livers, placentas and fetuses of the pregnant mice were detected by ELISA. The results showed the mortality and infectious rate of each group had no significant change. The average live embryo rate of PBS was lower than the STAg and ESA group. Compared with PBS group, the tachyzoite load in spleens in the immunized groups were significantly lower. The level of SIgA in intestinal washes of the combination of STAg and ESA group and ESA group were higher than the PBS group. The level of IgG in serum showed increasing tendency in the PBS, STAg, ESA and the combination of STAg and ESA group in order. The infection rate of embryos of the combination of STAg and ESA group was lower than those of other groups. These results suggested that BALB/c mice intranasal vaccination with the combination of STAg and ESA before the 29 days of pregnancy can induce higher level of SIgA in intestinal washes, the tachyzoite load in spleens decreased and higher embryo survival rate.