Our laboratory focuses on glycobiology of ticks and tick-borne pathogens, as well as protein-saccharide interactions important for the process of tick feeding and infection of tick vector and the vertebrate host. Laboratory members participate on projects studying the glycobiology of other organisms as well.
A) Fibrinogen-related proteins in ticks
Fibrinogen-related proteins (FRePs) with lectin activity were studied in the Dermacentor and Rhipicephalus ticks. These proteins participate in the tick innate immune response. All of the proteins were found to be glycosylated and a cross-reaction of anti-FReP antibodies with the tick storage protein Hemelipoglycoprotein (HLGP) was discovered; however the cross-reactivity is most probably dependent on the epitope similarity as sequence similarity was not found between fibrinogen and FRePs on one hand and HLGP on the other. The hemagglutination activity of Rhipicephalus ticks was inhibited by sialic acid and sialylated glycoproteins, GalNAc, and GlcNAc, suggesting similarity to another FReP from Ornithodoros moubata, the Dorin M protein. (Sterba et al., Parasite Vector 2011)
Mass spectrometric analysis of D. marginatus HLGP N-glycans in a collaborating Novotny laboratory (Indiana University, Bloomington, IN) showed the presence of high-mannose and complex type; paucimannosic type glycans were not observed. Furthermore, lectin-activity of HLGP was studied in collaboration with Wimmerova lab (Central European Institute of Technology, Masaryk University, Brno, Czech Republic). Highest binding activity was found for galactose. (Dupejova et al., Parasite Vector 2011).
B) Sialic acid in ticks
Sialylated N-glycans were detected in Ixodes and Dermacentor ticks – both N-acetylneuraminic and N-glycosylneuraminic acid (NeuGc) were detected again in collaboration with Prof. Novotny's group in Bloomington, IN. Antibodies against NeuGc were utilized for tracking of sialylated glycans in tick tissues and thus we showed the route of sialylated host glycoproteins from the tick gut through the hemolymph to the salivary glands, where they are in part excreted back into the host. (Vancova et al., J. Insect Physiol. 2012).
Next, we used a combination of sialic acid quantitation and detection of metabolically incorporated sialic acid (Click-iT chemistry) to determine expression of sialylated glycoproteins by the ticks themselves. Using this approach we showed, that majority of sialic acid present in fed female Ixodes ricinus ticks is coming from the host and not the tick itself. This can be one of the immune system evasion strategies employed by ticks (Sterba et al., Carbohydr. Res. 2014).
Recently, we work on the determination the importance of glycan moieties (NeuAc and NeuGc) for the infection of tick and host cells by the Anaplasma marginale MSP1a in collaboration with Prof. de la Fuente's laboratory (IREC, Universidad de Castilla-La Mancha, Ciudad Real, Spain). While it was previously shown, that Anaplasma infection of tick cells is dependent on the presence of core-fucosylated N-glycans, here we are showing for the first time the importance of sialic acid for the infection of tick cells. The presence of host sialylated molecules in tick tissues and on the surface of tick cells could explain these findings.
In the past years, the scope of our research in tick glycobiology moved from lectin-based analyses to up-to-date methods including mass spectrometry, SPR. In the future, the team will use newly acquired instrumentation at our campus as well as well-developed collaborations to further broaden our knowledge in basic tick glycobiology and also to better explain the role of protein-saccharide interactions for pathogen transmission. New goals will possibly arise to cope with new collaborations and new upcoming challenges related to tick-borne pathogens.