Research Of Egg Yolk Antibodies Against Cryptosporidium (C.baileyi)

Cryptosporidium oocysts were isolated from the feces of Gu-Shi chicking in Henan and multiplicated with partridges to gain purebred Cryptosporidium oocysts.The figure of the oocyst is elliptical,and the average of the oocysts is of 6.5μm×4.7μm with shape index of 1.31. In the animal infective tests, mice not infected in the normal or using immunosuppressant ,but the oocyst were orally inoculated into chickens , mainly parasitized in trachea, cloaca and bursa of Fabricious of chicken.It can be identified C. baileyi basing on the peculiarity of figure and parasitized. The effect of inoculated quantity and using immunosuppressant on the oocyst sheded in the feces and clinical symptom of chicking.The results suggested that modest increase inoculated amount and using immunosuppressant can advance and prolong the fastigium of oocysts sheded, boost up the intensity of sheding oocyst,but using immunosuppressant can not gain a great deal of oocysts as a result of increasing the mortality of experimental animal and reducing appetite ,further more the cost of test is added.The oocyts of C. baileyi strain were purified by amelioration discontinuous sucrose gradients, then treated by filtration and low speed centrifugation for eliminating bacterium, and arfter freeze-thawed and sonicated., mixed with Freund compiete or incomplete adjuvant to immunize the five-month-old laying hens.Four immunity procedure are setup for choosing the fittest .The result confirmed that the best immunity procedure was gradually augment the dosage of antigen :the dosage of antigen in the 1 st time and the 2nd time all is 1×107 oocysts per hen, 3× 107 oocysts per hen in the 3rd time and the 4th time, 5×107 oocysts per hen in the 5th time and the 6th time.and 15—20 days arfter the next immunity injection.The titers of yolk antibodies gradually raise,and rise to 1: 20000 (ELISA titer) after the 4th time, rise to 1: 144000 (ELISA titer, the extent of peak titer is l:384000～1:512000) after the 6th time.It was found that the...