Biochemical investigation with regard to infection and immunity of Eimeria acervulina in the fowl

Summary

Biochemical investigation of the fluid surrounding the sporocysts in the oocysts (“oocyst fluid”) showed the presence of the common amino acids, β-isoaminobutyric acid, glycerol, an unidentified carbohydrate and proteins.

Incubation experiments with D-glucose-¹⁴C (U) revealed the presence of enzymes able to convert glucose into lactic acid and other acids. Inside the sporocysts the common amino acids, glycerol and the unidentified carbohydrate were also present, but β-isoaminobutyric acid did not occur. The carbohydrate binding protein “carboglutelin”, carbohydrate phosphate and small amounts of glucose and fructose were mainly found inside the sporocysts.

Incubation experiments of oocyst fluid mixed with sporocysts with D-glucose-C¹⁴ (U) demonstrated an interchange between the fluid and the sporocysts. In the oocyst fluid lactic acid was formed, but inside the sporocysts the conversion appeared to stop mainly with formation of carbohydrate phosphate.

Incubation experiments of intestinal pieces both from immunized and not-immunized birds with oocyst fluid, sporocysts and labelled glucose showed that a stronger reaction took place in immunized birds than in not-immunized ones.

Similar experiments were performed with not-immunized birds at different days after a primary infection. The reaction of the intestinal wall, which seemed quite normal again since day 19 after infection, was comparable with that observed in immunized birds.

Finally the hypothesis is given, that in the first part of the intestine of immunized birds compounds are present originating from the first infection. These compounds might enhance the reaction between the oocyst fluid and the present feed to such an extent that the pH decreases and much epithelial cells are pushed off possibly together with the sporocysts. Then leakage of serum proteins might occur.