CHARACTERIZATION OF PARASITE ANTIGENS ... - PAHO/WHO

complete Freund's adjuvant. A rabbit received six injections
over a three-week period, or a total of 12 mg of antigen. We
thought we were injecting-large doses of antigen. Biguet and
Capron use 20 mg of antigen per inoculation (14). The antisera
they employ after six months or one year of immunization con-
tain many more antibodies to major and trace components in the
antigens they assayed. It i's for this reason that Biguet et al
(19) reported so many cross-reactions between cestodes, helminths,
and nematode species. The differentiation of closely related
species is also difficult with such composite antisera (13).
Common antigen between adult S. mansoni and the laboratory
mouse host were demonstrated by Damian (28). At least four
common antigens were found between S. mansoni and serum antigen
of the mouse. In addition a Forssman hemolysin was demonstrated
in rabbit anti-schistosome sera. Analysis of the various stages
of the schistosome life cycle were made by Capron et al. (20).
These workers were able to demons¿rate 21 antigens in extracts
from adult worms, 11 shared by adult and egg, 14 with cercariae,
and 12 with excretions and secretious products. There were four '
bands common between the parasite and the hamster host and five
common between the parasite and the snail host (ustralorbias
glabratus). Dusanic and Lewert (34) labelled extracts of S. mansoni
with 1131 Utilizing this method they were able t!differentiate
14