Fibrinogen-related proteins in ixodid ticks

Abstract

BackgroundFibrinogen-related proteins with lectin activity are believed to be part of the tick innate immune system. Several fibrinogen-related proteins have been described and characterised mainly on the basis of their cDNA sequences while direct biochemical evidence is missing. One of them, the haemolymph lectin Dorin M from the tick Ornithodoros moubata was isolated and characterised in more depth.ResultsSeveral fibrinogen-related proteins were detected in the haemolymph of ixodid ticks Dermacentor marginatus, Rhipicephalus appendiculatus, R. pulchellus, and R. sanguineus. These proteins were recognised by sera directed against the tick lectin Dorin M and the haemagglutination activity of the ticks R. appendiculatus and D. marginatus. Cross-reactivity of the identified proteins with antibodies against the fibrinogen domain of the human ficolin was also shown. The carbohydrate-binding ability of tick haemolymph was confirmed by haemagglutination activity assays, and this activity was shown to be inhibited by neuraminic acid and sialylated glycoproteins as well as by N-acetylated hexosamines. The fibrinogen-related proteins were shown to be glycosylated and they were localised in salivary glands, midguts, and haemocytes of D. marginatus. Hemelipoglycoprotein was also recognised by sera directed against the fibrinogen-related proteins in all three Rhipicephalus species as well as in D. marginatus. However, this protein does not contain the fibrinogen domain and thus, the binding possibly results from the structure similarity between hemelipoglycoprotein and the fibrinogen domain.ConclusionsThe presence of fibrinogen-related proteins was shown in the haemolymph of four tick species in high abundance. Reactivity of antibodies directed against ficolin or fibrinogen-related proteins with proteins which do not contain the fibrinogen domain points out the importance of sequence analysis of the identified proteins in further studies. Previously observed expression of fibrinogen-related proteins in haemocytes together with the results of this study suggest involvement of fibrinogen-related proteins in tick immunity processes. Thus, they have potential as targets for anti-tick vaccines and as antimicrobial proteins in pharmacology. Research on fibrinogen-related proteins could reveal further details of tick innate immunity processes.

A Deep Insight into the Sialotranscriptome of the Gulf Coast Tick, Amblyomma maculatum

“…Pathogen-recognition proteins of the peptidoglycan-recognition family, of the ixoderin/ficolin family of fibrinogen-domain containing proteins [148], [149], [150], and of the ML domain family [2], [151] are also represented.…”

Interaction of the tick immune system with transmitted pathogens

“…The activity of lectins/hemagglutinins with preferential binding specificity for N-acetyl-D-hexosamines, sialic acids and glycoconjugates have been identified in the hemolymph of several hard and soft tick species (Grubhoffer et al, 2008; Sterba et al, 2011) and is mainly attributed to the presence of fibrinogen-related proteins (FREPs) related to Dorin M, isolated and characterized from the soft tick O. moubata (Kovar et al, 2000; Rego et al, 2006). In contrast to mammalian ficolins, Dorin M lacks the N-terminal collagen-like domain and is closely related to the lectins of tachylectin-5 type known to function as pattern recognition molecules in the horseshoe crab immune system (Gokudan et al, 1999; Kawabata and Tsuda, 2002; Ng et al, 2007).…”

Transmission-Blocking Vaccines: Focus on Anti-Vector Vaccines against Tick-Borne Diseases

“…Fibrinogen-related proteins are shown to be important for tick innate system and are suggested to be potential candidates for the development of anti-tick vaccines (Hajdusek et al 2013 ). Recent study has identified fibrinogen-related proteins from D. marginatus , Rhipicephalus appendiculatus , R. pulchellus and R. sanguineus (Sterba et al 2011 ). Dermacentor ticks feed for 6–10 days with varying expression levels of several tick proteins involved in the process of blood feeding (Sonenshine and Roe 2014 ).…”