Excystation of Isospora brachyrhynchi Cawthorn and Wobeser, 1985, in vitro

I. brachyrhynchi were recovered from faeces of experimentally infected juvenile crows (Corvus brachyrhynchos) and stored for up to 12 months in a 2.5% (w/v) solution of potassium dichromate at 4 degrees C. Sporocysts were released from the oocysts by grinding in a homogenizer. Various bile salts, taurocholic acid, pooled chicken bile, sodium glycocholate and sodium taurodeoxycholate were used in conjunction with trypsin as media to excyst sporozoites of I. brachyrhynchi. These media were tested at different temperatures and on oocysts stored for varying lengths of time. The most effective excystation (94%) was seen in oocysts that had been stored for 1 month and were incubated with 5.0% sodium taurodeoxycholate and 0.25% trypsin at 41 degrees C for 60 min. Varying degrees of excystation were observed using different bile salts at different temperatures on oocysts stored for up to 12 months..