in vitro culture and isoenzyme analysis of giardia lamblia

cultivation in vitro (Kasprzak & Majewska, 1985; Isaac-Renton et al., 1986; Meloni
& Thompson, 1987; Hautus et al., 1988; AI-Tukhi et al., 1991; Feely et al., 1991;
Korman et al., 1992).
Bingham et al. (1979) investigated the effects of several factors on Giardia spp.
excystation in vitro and noted that temperature, pH, time and incubation medium
affect the levels of excystation achieved. They deduced that in general, those
conditions most closely approximating the organism's in vivo environment induced
the highest levels of excystation. Similarly, Schaeffer et al. (1984) studied the
factors promoting in vitro excystation of Giardia muris cysts. They reported similar
conditions to those noted by Bingham et al. (1979) and further deduced that in
addition, the presence of C02 and positive oxidation-reduction potentia Is were
equally essential. Various combinations of solutions were used to induce
excystation, some containing pepsin digest and others with trypsin. They reported
that trypsin accentuated excystation as it enhanced the escape of the trophozoites
from cysts. There was a significant increase to over 90% excystation when a
solution containing trypsin was used in place of a pepsin digest. However, Buchel
et al. (1987) studied in vitro excystation of G.lamblia in detail using a scanning
electron microscope and indicated that for G./amb/ia, best excystation is obtained
when pepsin is used.
The effector mechanisms of the excystation process are not completely
understood, however, many enlightening findings have been reported. Feely et al.
(1984) described contractile systems that are responsible for excystation. Coggins
and Schaefer (1986) proposed the possibility that enzymatic agents are
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