Lectins and their glycosylated receptors in a system of the tick-transmitted pathogen are the addressed topics which the minireview is dealing with. They participate in the reciprocal protein-saccharide interactions in the transmission of the causative agents of the tick-borne encephalitis and Lyme borreliosis by the ticks. Functional significance of the tick tissue specific lectins as well the lectins/aggulutinis of the transmitted pathogens in molecular ecology of the tick borne diseases has been shown.
Lectins as carbohydrate recognition proteins other than enzymes or immunoglobulins play important roles in living systems, e.g., in celi celi recognition. They are considered to be involved in snail-trematode immune interactions, i.e., in a system where antibodies are lacking and lectins might at least partially substitute immunoglobulin functions. From the snail side, lectins can be located on haemocyte surfaces as receptors for foreignness and they can be found freely in plasma. The latter can function as agglutinins/opsonins helping in the recognition of parasites by haemocytes. They may also link immune cells and pathogens by recognition of surface carbohydrates on both. Lectins of parasite origin could also be involved in snail-trematode interactions. They might function as trematode surface receptors for snail glycoconjugates in parasite masking strategies. Functions other than the involvement in the snail's immune response or the parasite’s evasion strategies might be fulfilled by lectins as well. Among these may be host-finding, penetration, orientation in the host, nutrition. It cannot be omitted that lectin-saccharide reactions represent only a part of the snail-trematode interactions and thus, results obtained from lectin experiments are a rough simplification of the actual, very complicated situation. An array of immune and other reactions comprised of yet unknown bioactive molecules certainly exists in snails and, on the other hand, trematode mechanisms to escape or otherwise interact with these, might be involved at the same time. But we can certainly conclude that a more complete view of the complex snail-trematode interactions also necessitates a more profound knowledge of the identity and functioning of lectins and their ligands, in host and parasite.
Haemagglutination activity (HA) was found and characterized in a midgut homogenate of Ixodes ricinus (L.). HA was induced by tick feeding; it was not detected in starved ticks. In a haemagglutination inhibition test, HA showed an affinity for some carbohydrates (N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, rhamnose, and dulcit) and glycoconjugates (especially lipopolysaccharides). Midgut protein components of 37, 60, 65, and 73 kDa were identified by immunoblotting as potential structural subunits of the new agglutinin.