A carbohydrate antigen specific to the larvae of the sheep nematode T. colubriformis was recognized by mucus antibodies of immune sheep, and passive-transfer experiments using IgG against this antigen indicate that it may be a target of protective immunity (93). Also, an anti-pathogenesis vaccine is being developed against the glycosylphosphatidylinositol (GPI) molecule of Plasmodium falciparum; when the synthetic carbohydrate was conjugated to a protein
carrier (keyhole limpet haemocyanin) and used to immunize mice, IgG specific for the native glycan were induced. While parasite numbers were not reduced in this model, mice were protected from severe malaria (94); further data indicate BVD-523 research buy that anti-GPI antibodies convey a similar mode of protection in humans (95). Similarly, a RXDX-106 molecular weight Leishmania carbohydrate antigen and vaccine candidate was synthesized, linked to a protein carrier and loaded onto virosomes
to increase its antigenicity (96). When mice were immunized with this construct, specific IgG1 was produced which bound to the parasite surface. These studies indicate that with the discovery of the right parasite glycan structures, immunization with synthetic forms is capable of inducing IgG, which can have a protective in vivo effect. Schistosomes induce a profound anti-carbohydrate response, primarily against the most Thalidomide abundant glycoconjugates present on the surface and secreted products of the different developmental stages (62,85). Thus, glycomics is currently a vibrant area of schistosome research, and many unique glycans have been found decorating the schistosome surface – although the entire glycome is far from complete (60). Some researchers consider the most abundant schistosome glycans, which are also highly immunogenic, to be important vaccine candidates (62,92). Adding weight to this argument is the observation that the protective antibody response produced after vaccination with radiation-attenuated
cercariae is predominantly against carbohydrates (97), and in vitro experiments show that an antibody against one of the most abundant surface glycans, lacdiNAc (LDN), can induce complement-mediated killing of newly transformed schistosomula (62). Despite this, others have proposed that this anti-glycan response is not in fact protective and that these abundant carbohydrates may function as evasive tools to divert and modulate the immune response (78,97). There are also conflicting reports on the importance of one glycan structure in vaccine-induced protection against H. contortus. One study found that IgG levels against a fucosylated form of LDN (LDNF), also present on schistosome antigens, correlated with protection against H. contortus with native secreted proteins (98).