Three proteins were recognised by anti-(RA)HA serum also in R. 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 name and thus, the binding possibly results from the structure similarity between hemelipoglycoprotein and the fibrinogen domain name. Conclusions The presence of fibrinogen-related proteins was shown in the haemolymph of Rabbit Polyclonal to NDUFA3 four tick species in high large quantity. 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. Background Together with mosquitoes, ticks are the AZD5991 primary vectors of a broad-range of dangerous human and animal pathogens. Some of the well-known infections transmitted by hard ticks (Ixodidae) are Rocky Mountain spotted fever, ehrlichiosis, tick-borne encephalitis, Lyme borreliosis, theileriosis or babesiosis while soft ticks (Argasidae) are vectors of African AZD5991 swine fever and tick-borne relapsing fever [1,2]. Tick haemolymph is a complex fluid composed of plasma and haemocytes. It serves several functions such as transportation of nutrients but it contains also the components of the immune system and helps the tick to fight injuries. Until now, haeme-storage proteins [3,4], defensins [5-7], a tick haemolymph lectin Dorin M from Ornithodoros moubata [8,9], and several others have been described. Tick defence against pathogenic microorganisms is based on recognition of pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharides or peptidoglycans with lectins [10]. Invertebrate/arthropod lectins are believed to be functional analogues of immunoglobulins due to their specific binding to surface carbohydrate structures of pathogens [11]. AZD5991 In arthropods, fibrinogen-related proteins (FRePs) are described as humoral factors of the innate immune system with the ability to recognise PAMPs. FRePs are molecules containing fibrinogen-related domain in the C-terminus; some of these domains exhibit carbohydrate-binding activity [12,13]. FRePs from Tachypleus tridentatus (Tachylectin 5A and 5B) with high-sequence homology to human ficolins selectively bind terminal N-acetyl group of sugars [14] and this lectin-activity is important in the innate immunity processes [12]. Lectins/FRePs have been found in several ticks [8,15-17] in the haemolymph, the midgut, and salivary glands (SGs) [reviewed in [11]]. Generally, tick lectins display affinity towards sialic acid [8] and N-acetyl-D-glucosamine (GlcNAc) [15] as well as galactose [17]. Several FReP-encoding sequences were also described to date: Ixoderin A, Ixoderin B, Ixoderin A-like (Ixoderin ricinus), Dorin M, AZD5991 and OMFREP (O. moubata) [18]. The OMFREP mRNA is detected in haemocytes and SGs. Ixoderin A is expressed in haemocytes, SGs, and the midgut; Ixoderin B is expressed mainly in SGs and weakly in haemocytes [18]. Sequence similarity of the identified tick lectins with Tachylectins suggests their involvement in innate immunity [9]. Dorin M is still the only purified tick lectin. It is a 640 kDa homomer composed of subunits with 37 kDa [8] and exhibits haemagglutination activity, which is inhibited by N-acetylated hexoses, N-acetyl neuraminic acid, and sialylated glycoproteins [8,9]. The protein is glycosylated and as such it is recognised by several lectins specific for high-mannose and complex glycans [8]. Three N-glycosylated sites described in the protein bear two high-mannose glycans with up to nine mannose residues and a core-fucosylated paucimannosic structure [19]. In I. ricinus, 85 kDa lectin was partially characterised with specificity for N-acetyl neuraminic acid, N-acetyl glucosamine, and D-galactose; however, its sequence.