The Observation Of Immune Protection Induced By Soluble Immature Eggs Antigen Of Schistosoma Japonicum Yunnan Strain

(Objectives] To observe ultrastructurally the testes and vitelline gland of Schistosoma japonicum in mice immunized by immature eggs antigen(SIEA) of S. Japonicum Yunnan strain to discuss the anti-fecundity mechanism. To observe the anti-pathology effect induced by SIEA. To study whether the anti-pathology immunity can be induced in mice immunized by SEEA Yunnan strain but challenged with Wan'e strain cercariae.[Methods] SIEA of S. Japonicum Yunnan strain was prepared. ICR mice were immunized by repeated subcutaneous injection antigen and adjuvant and then challenged with 30+2 cercariae of Yunnan and Wan'e respectively. On day 46 post challenge infection the mice were sacrificed and values were compared with those obtained from control groups. The values included worm reduction,the reduction rate of egg number in faeces,female uterus and liver, the number of egg node in liver surface, and proportion of different stages of egg in liver. The granulomas of mice liver were studied histopathologically and the mean size of granulomas was analyzed. The vitelline gland of adult female and testes of adult male worms were observed by transmission electron microscopy.[Results]There was no significant worms reduction between immunized and unimmunized mice. The egg reduction rate in faeces were 33.25%,34.45% (P<0.05) respectively in Dali and Huadong group and the eggs in female uterus reduced by 34.75%,23.69% (PO.05) respectively. The number of egg node in liver surface and the diameter of granulomas in liver were also significantly decreased, the former was 47.76 % ,29.03 % (P<0.05) respectively and the latterwas 49.06%,30.69% (P<0.05) respectively. The total egg counts in liver per female decreased by 41.83%,29.07% (P<0.05) respectively and the mature egg counts in liver per female decreased by 54.37%,48.4I % (P<0.05) respectively. The proportion of mature eggs decreased and which of immature eggs increased (P<0.05) . The inflammation granulomas was gently and a few of hepatocytes were necrotic accompanied with a few of granulocytes infiltration compared with control group.The ultrastructure of the main reproductive organs of adult worms showed that mature vitelline cells and lipid droplets in the cytoplasm of vitelline cell were decreased in vitelline gland and more sustentacular cells and few spermatid could be seen in testes in immunized mice.[Conclusions] The antigenicity of SIEA is strong and anti-fecundity and anti-embryonation immunity are induced in mice immunized with SIEA of S. Japonicum Yunnan strain and SIEA plays an important role in inhibition on liver granuloma formation. In immunized mice the main reproductive organs of adult worms are influenced and the antigen inhibits mature of germinal cells so that the anti-fecundity effect are produced. Anti-pathology immunity are also induced in mice challenged with S. Japonicum Wan'e strain cercariae. SIEA of S. Japonicum Yunnan strain has anti-pathology immunity effect and can be as a promising candidate antigen.