A. Joachim et al., Changing surface antigen and carbohydrate patterns during the development of Oesophagostomum dentatum, PARASITOL, 119, 1999, pp. 491-501
Living and fixed specimen of Oesophagostomum dentatum were labelled in situ
with serum antibodies or a panel of biotin-labelled lectins. Specific bind
ing of antibodies was observed in all parasitic stages - freshly exsheathed
3rd-stage larvae (L3), 3rd- and 4th-stage (L4) larvae cultured in vitro an
d L3 and L4 and adults isolated from pig intestines. The shedding of the st
ained layer by motile larvae was inhibited by levamisole-induced paralysis.
Larvae cultured in vitro exposed serum-derived proteins on their surface w
hich could be labelled with secondary antibody directed against the respect
ive serum donor species. While freshly exsheathed larvae were recognized by
O. dentatum-positive serum only, older larvae and adults cross-reacted wit
h serum from pigs infected with O. quadrispinulatum, a closely related spec
ies. Lectin binding varied considerably between stages. While binding was n
ot observed in pre-parasitic stages, Concanavalin A, Soybean Agglutinin, Wh
eat Germ Agglutinin, Ricinus communis Agglutinin and Peanut Agglutinin boun
d to developing larvae in varying degrees. Dolichos biflorus Agglutinin onl
y bound to advanced (luminal) larval stages, while adults generally display
ed only weak or partial lectin binding (except with Concanavalin A and Whea
t Germ Agglutinin). Ulex europaeus Agglutinin only labelled larvae derived
from cultures containing 10% pig serum. Cleavage of the carbohydrate residu
es by sodium periodate treatment resulted in reduction of antibody binding
to cultured larvae, but not to freshly exsheathed L3. Concanavalin A, Soybe
an Agglutinin, and Peanut Agglutinin binding was also reduced by periodate
treatment, while binding of Wheat Germ Agglutinin and Ricinus communis Aggl
utinin was inhibited only in early L3, but not in older stages. The differe
nt lectin labelling patterns are related to the different stages of the nem
atode - infective, invasive, histotropic, and luminal - and may serve as a
mode of adaptation for the parasite against the host's immune attack by sur
face glycoprotein variation, together with antigen shedding (as demonstrate
d by labelling of motile larvae) and a possible acquisition of host molecul
es at the parasite's surface. Furthermore, a possible role of this developm
ental variation in surface carbohydrates in parasite-parasite interactions
is discussed.