| Purpose of studyBy via of creating animal model of immunosuppressed rabbits infected with toxoplasma, we observed desease episoding , antibody developing changes, distribution of toxoplasma and antigen in each organ and histopathological features of constitutions in order to analysis and investigate episoding characteristic, immunological features and pathogenic phenomenon when rabbits infected with toxoplasma. So we can deduce immunity and pathogenic mechanism exactly and trustly while immunocompromised persons infected by toxoplasma for exact diagnosis of toxoplasmosis and reasearch of anti-toxoplasma infection,and it is of important themry and instruction significance for preventing and controlling toxoplasmosis.Methods of studyTwenty rabbits whose body weight(BW)was about 2kg and antibody(IgM and IgG)in serum was negative after ELISA detecting were randomly divided into four groups: A group: normal control group, B group: immunosuppressed group injected with DEX, C group: control group infected with T gondii, D group: immunosuppressed group injected with T gondii after injecting desamethasone(DEX). A group had no any treatment, B group was muscularly injected with DEX (2mg/each/day), C group was peritoneally infected with tachyzoites of RH strain(5×104/each), D group was muscularly injected with DEX (2mg/each/day)72 hours prior to inoculation and was peritoneally infected tachyzoites of RH strain(5×104/each)after 72 hours. We observed hairs, body weight, appetite, secretion of eyes and changes of fundus of eyes with funduscope. We collected blood from ear-border vein at the day of 0,5,7,9,12,15,18,22,26,30,34,38,42,46 after inoculation and detected toxoplasma antibody(IgM and IgG)contents in serum with ELISA. We put rabbits to death at the day of 50 after administration, dissected , selected eye, brain, lung, heart, liver, spleen and observed having lesions or not with naked eyes; then printing constitutions on slides, staining in Gimesa-Wright liquid to observe distribution of tachyzoites for light microscopy; embed liver and brain fixed in paraffin and cut sections and detected with immunohistochemistry(SABC method) to observe distribution of toxoplasma antigen for light microscopy;embed constitutions fixed in paraffin and cut sections and stained with hematoxylin-eosin to observe histopathological features of constitutions for light microscopy.Results and discussion1. rabbits episoding During the experiment, appearance and behavior of rabbits of normal control group and immunosuppressed group had no changes. Rabbits of control group infected with toxoplasma presented hairs rarefaction at the day of 6 and basicly presented normal after ten days. There was no dying throughout the experiment; immunocompromised rabbits presented hairs rarefaction at the day of 4 and presented dehairing, activities decreasing, anorexia, BW descending, abdomen exponding, having secretion in eyes; symptom gradually relieved and tended to be normal after drug withdrawal; after administration again, presented above symptom again, respiring urgently, opic papilla hyperemia gently. A rabbit presented limbs paralysing, convulsion, coma and died, which indicated that the more episoding, the severer lesions.We can detected from the experiment that rabbits of control group infected with toxoplasma occurred temporary attack, following protective immunity yielded, symptom gradually relieved and disappeared, probably transformed into subclinical infection. Rabbits of immunosuppressed group injected with toxoplasma presented overt disorder after two administration replicatedly, which indicated immunosuppressive agent can induce toxoplasmosis episoding, and symptoms are severe but last for a long time, the severe person can endanger life to die. 2. antibody developing changes of rabbits in serum Rabbits of both normal control group and immunosuppresed group were not inoculate toxoplasma, so had no specific antibody ,and curves had no developing changes yet. IgM of rabbits injected wi...
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