Studies on the excystation of different species ofEimeria in vitro
Tóm tắt
The role of enzymes in the excystation of an embryo-adapted strain ofE. tenella (TA) was investigated; 0.1% crude trypsin or pure trypsin in combination with 0.5% bile salt resulted in 75% and 58% excystation respectively. Both enzymes were more effective than chymotrypsin. Addition of 0.01% chymotrypsin to 0.1% purified trypsin resulted in 76% excystation suggesting that both trypsin and chymotrypsin may be important for excystation in vitro. Pre-incubation of sporocysts in 2% bile salt prior to the addition of enzyme resulted in lower excystation. Sporozoites released at various enzyme concentrations did not differ in infectivity when inoculated into chicken embryos. Excystation of the Houghton strains ofE. acervulina, E. praecox andE. maxima occurred more rapidly at lower concentrations of crude trypsin plus 0.5% bile salt than the Houghton strains ofE. brunetti orE. tenella. Sixty per cent of sporozoites ofE. acervulina had excysted after 25 min incubation with 0.001% crude trypsin plus 0.5% bile salt. At the same concentrations 72%E. praecox had excysted after 25 min, 43%E. maxima after 60 min, 20%E. brunetti after 105 min and 1%E. tenella after 105 min. Maximum numbers of sporozoites ofE. brunetti andE. tenella were found after 105 min incubation with 0.1% crude trypsin. Whereas incubation ofE. acervulina, E. praecox andE. maxima for 105 min in 0.01% crude trypsin resulted in sporozoite lysis, no lysis was found withE. brunetti orE. tenella after incubation in crude trypsin.
Tài liệu tham khảo
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