The Study For Pathology In KM Mice Toxoplasma Gondii Tachyzoites Intraperitoneal Infection And The Distribution Of MIC3 In Tachyzoites

To research the pathological changes of Kunming Mice after the acute Toxoplasma gondii infection and the Distribution of Microeme Protein 3 (MIC3) in Toxoplasma gondii, in this paper, we selected 25 45 to 55-day-old female KM Mice to be infected with Toxoplasma gondii by intraperitoneal injection. Each mouse was injected 0.2mL, which contains 1×105 international standard RH type I strain of Toxoplasma gondii. Through the clinical symptoms, they all have been infected. In the sterile environment, broke the neck of KM Mice infected with Toxoplasma gondii and collected the peritoneal fluid. Tachyzoites vitality were observed with the microscopy and the number of tachyzoites in the collected peritoneal fluid was counted by hemocytometer. Gondii strains were stored at 4℃,-20℃,-80℃ respectively and the length of Toxoplasma gondii survival time was observed under certain circumstances. Immunofluorescence staining was used on peritoneal fluid smear to observe the expression of MIC3 in Toxoplasma gondii. Heart, liver, spleen, lung, kidney and brain were taken to make paraffin sections and then the distributions of Toxoplasma gondii in various tissues and organs were determined by the pathological autopsy examination, HE staining, immunohistochemistry, Indirect immunofluorescent assay and transmission electron microscopy. The experiment alresults are as follows:1. Clinical Diagnosis:Attacking-larvae test was used to KM Mice and its clinical symptoms were observed. After 24 hours, its spirit and activity slightly decreased, but the eating and drinking were normal. After 48 hours, it was in a poor mental condition and the feed water intake decreased. After 72 hours, it depressed and lay down. It couldn’t move unless it was stimulated, the feed water intake obviously decreased and the erect back hair, arched back and intumescent abdomen appeared. Then the KM Mice had been infected with Toxoplasma gondii. Hanging drop slides could be made by collecting peritoneal fluid. With the microscope, a lot of viable Toxoplasma gondii tachyzoite and cell components of macrophages, lymphocytes, mast cells were observed.2. Toxoplasma conservation experiment results:In 4℃, Toxoplasma gondii tachyzoite still had vitality after 15 days and could infect the mouse; in-20℃, live tachyzoite still was observed under the microscope after 30 days and the mouse became sick after vaccinated; in-20℃ for 50 days, after the mouse was infected by larvae and were surely sick, lots of tachyzoite can be seen in peritoneal fluid.3. Post-mortem of the mice:abdominal congestion; liver, spleen enlargement; white necrosis in liver; mesenteric lymph nodes, intestinal congestion was seen.4. Histopathological changeHE staining showed that:in a 20 infected groups, tachyzoite, cysts and pseuddcyst were found in liver and spleen among the 18 KM Mice. Alveolar wall capillary dilatation and congestion, cardiac interstitial widened and congestion, arteries expanded, tubular epithelial cell swelling, necrosis and renal tubular capillary congestion were observed.Immunohistochemical staining showed that:the heart, liver, spleen, lung, kidney and brain of the infected mice were positive. In the abdominal tissue, there was a strong edge positive, which had a relationship with the tissues and organs’s direct contact with tachyzoite when did the intraperitoneal injection. Results indicated that Toxoplasma gondii antigens expressed in various tissues entered into various tissues with the blood circulation and sickened the mice.5. Immunofluorescence staining showed that:Through the immunofluorescence staining, we observed that its immunogenicity of expression MIC3 on the toxoplasma was positive.All of these results indicated that KM Mice was susceptible to Toxoplasma gondii. After the intraperitoneal injection, Toxoplasma gondii first invaded the liver, spleen. Through the blood circulation, Toxoplasma gondii entered into various organs and caused certain pathological changes. KM Mice’s infection of Toxoplasma gondii was an acute process, necropsy lesions was relatively minor and Toxoplasma gondii invaded all nucleated cells.