REVIEW ISJ 8: 231-240, 2011 ISSN 1824-307X REVIEW Immunomodulatory effects of tick saliva MI Camargo Mathias1, KC Scopinho Furquim2, PH Nunes1 1Department of Biology, Biosciences Institute, UNESP, Av. 24 A, nº 1515, Cx. Postal 199, CEP: 13506-900, Rio Claro, S.P., Brazil 2Department of Veterinary Pathology, FCAV, UNESP, Via de Acesso Prof. Paulo Castellane, s/n, CEP: 14884- 900, Jaboticabal, S.P., Brazil Accepted December 6, 2011 Abstract Ticks are bloodsucking ectoparasites that cause great damage to host organisms, so these ectoparasites are of great importance in medicine and veterinary medicine. All the biological success achieved by ticks is due to the action of bioactive components present in their saliva, which are synthesized by the salivary glands. These components have great diversity of functions such as enabling feeding and the permanence of ectoparasites on hosts, since they modulate immune system acting as complement inhibitors, immunosuppressors, cytokine expression modulator and chemokine binders of hosts. In addition, these components are an important source of protective antigens. In this sense, salivary glands/saliva are considered a potential source of multifunctional molecules. In this context, many studies have been conducted aiming at searching to establish a better understanding on the biology and morphophysiology of some organs such as salivary glands, as well as elucidate the complex relationship of these ectoparasites with their hosts. Such studies are conducted with the main objective of developing new immunobiological products aimed at the alternative control of ticks, as well as for the identification and isolation of bioactive molecules with pharmacological properties and with great therapeutic potential in the search for treatments for some diseases. Key Words: tick saliva; immunomodulation; immunosuppression; salivary glands Introduction Ticks are bloodsucking ectoparasites that can parasitize animals of different groups such as mammals, birds, reptiles, amphibians (Keirans and Durden, 2005; Anderson and Magnarelli, 2008) and even spiders, including ticks themselves (Labruna et al., 2007). These ectoparasites have broad geographic distribution, and can be found in all regions of the planet (Keirans and Durden, 2005; Anderson and Magnarelli, 2008). Ticks are animals belonging to the phylum Arthropoda, subphylum Chelicerata, class Arachnida, subclass Acari, order Parasitiformes and suborder Ixodes. These ectoparasites are divided into four families, namely: Ixodidae, Argasidae, Nutalliellidae and Laelaptidae, the first two being the most important, totaling 878 species (Anderson and Magnarelli, 2008). ___________________________________________________________________________ Corresponding author: Maria Izabel Camargo Mathias Department of Biology Biosciences Institute UNESP, Av. 24 A, nº 1515 Cx. Postal 199, CEP: 13506-900, Rio Claro, S.P., Brazil E-mail: micm@rc.unesp.br Ticks are arthropods of great medical and veterinary importance because they are vectors of bacteria, viruses, protozoa and helminthes to their hosts, affecting domestic animals, wildlife and humans (Jongejan and Uilemberg, 2004; Dantas- Torres et al., 2010), besides causing considerable economic losses. Considering that ticks remain attached to their hosts feeding for weeks, they must have a large, diverse and effective pharmacological arsenal to ensure their survival and feeding (Wikel, 1999, Sauer et al., 2000; Francischetti et al., 2005; Steen et al., 2006), which can be rapidly introduced into the host. Thus, throughout evolution, salivary glands have specialized in the production of a secretion called saliva, which has such capability. The present review will focus only on immunomodulatory effects of tick saliva. Salivary glands of ticks The salivary glands of ixodid (family Ixodidae) are vital organs for the biological success of this group, since they have wide variety of functions such as the production of substances necessary for 231 the fixing and feeding of ectoparasites (Binnington, 1978; Walker et al., 1985; Gill and Walker, 1987). The presence of these organs and their role in hosts to give these ectoparasites the status of one of the most important groups within the group of arthropods. Their salivary glands are also responsible for the transmission of infectious agents to other groups of animals (Balashov, 1983). Morphologically, salivary glands of ixodid ticks are formed by an excretory portion composed of a common excretory duct, intermediate ducts and acinar ducts responsible for collecting and secretion of saliva produced in the secretory portion. The latter consists of types I, II, III and IV acini, the latter present only in males (Binnington, 1978; Walker et al., 1985; Fawcett et al., 1986; Gill and Walker, 1987; Sonenshine, 1991; Furquim et al., 2008a, b, 2010). Type I acini are nongranular and act in the water balance of the ectoparasite, while type II, III and IV acini are granular and act in the feeding process (Binnington, 1978; Walker et al., 1985), in osmoregulation in the phase of large blood consumption (Kaufman and Sauer, 1982; Sonenshine, 1991) and in reproduction (Feldman- Muhsam et al., 1970). The salivary glands of ticks have no reservoir to store secretion, which is released as soon as it is produced (Binnington, 1978; Balashov, 1983; Walker, 1985; Nunes et al., 2008). Type I acini consist of a large central cell, surrounded by several smaller peripheral cells (Binnington, 1978; Walker et al., 1985; Fawcett et al., 1986; Gill and Walker, 1987). Type II acini are formed by types a, b, c1, c2, c3 and c4 secretory cells (Binnington, 1978) and in females of R. sanguineus, and in addition to those, c5 and c6 cells have been recently described (Furquim, 2007). It is known that a cells are involved in the secretion of the cement (Binnington, 1978; Walker et al., 1985; Fawcett et al., 1986; Gill and Walker, 1987), and b and c are involved with the manipulation of the host response (Binnington, 1978; Walker et al., 1985). Type III acini, in turn, are composed of three cell types, d, e and f (Binnington, 1978; Walker et al., 1985; Gill and Walker, 1987; Furquim, 2007), where d and e secrete components of the cement during attachment (Binnington, 1978; Walker et al., 1985; Gill and Walker, 1987), and f cells secrete substances related to the consumption of blood by the ectoparasite (Binnington, 1978). The new classification of the salivary gland cells of Rhipicephalus sanguineus established by Furquim (2007) included a larger number of secretory types present in type II acinus (females), unlike those previously described in literature (Binnington, 1978, Walker et al., 1985). Moreover, the author has shown that these new types (c5 and c6), and f of type III acini would be activated and inactivated at specific moments of the glandular cycle (when the tick had already fed for two and four days), while the other types would remain continuously active until the complete engorgement of the female, becoming inactive, beginning the death process (Furquim et al., 2008a, b). This was evidence that the activity of c5, c6 and f cells would be essential for feeding and permanence of ticks in the host, therefore acting specifically in the manipulation of their immune response. Type IV acinus, exclusive to males, consists of a single cell type, g (Binnington, 1978; Furquim et al., 2008a, 2010). In some ixodid, its product participates in the secretion of the cement (Fawcett et al., 1986) and can also produce other secretions important in the transfer of the spermatophore to the female (Feldman-Muhsam et al., 1970). Functions of the tick saliva The tick saliva is a mixture that plays a variety of roles during parasitism and non-parasitism periods, as: modulating the immune system of the host (Fawcett et al., 1986; Ribeiro et al., 1985; Wikel, 1999; Sauer et al., 2000); attaching the tick to the host skin through the secretion of cement to form the cone (Fawcett et al., 1986); excreting excess water and ions from the food (blood) (Sauer et al., 2000); secreting hygroscopic solution, which is deposited in the mouth region and absorbs atmospheric water, hydrating the ectoparasite during non-parasitism periods (Sauer et al., 2000; Bowman and Sauer, 2004); producing secretions that lubricate the spermatophore during its transfer to the female during copulation (Feldman-Muhsam et al., 1970); releasing toxins that cause paralysis in the host (Fawcett et al., 1986) and conveying pathogens to the host (Fawcett et al., 1986; Wikel, 1999; Sauer et al., 2000; Bowman and Sauer, 2004). Immunomodulation of host immune responses Given the importance of components synthesized by type II and III acini for the feeding and fixing of ticks (Binnington, 1978; Walker et al., 1985), these components should be studied in more depth (Jittapalapong et al., 2008). Proteins, glycoproteins, lipoproteins and lipids are among products with pharmacological and immunological properties present in the saliva of ticks (Binnington, 1978; Wheeler et al., 1991; Shipley et al., 1993), such as acid phosphatase, esterases, aminopeptidases, metalloproteases, calreticulin, esterase, prostaglandins, lipocalins (Binnington, 1978; Gill et al., 1986; Jaworski et al., 1995; Brossard and Wikel, 2004; Steen et al., 2006; Harnoi et al., 2007; Mulenga et al., 2007; Kaewhom et al., 2008; Konnai et al., 2010; Oliveira et al., 2011), among many others. Although the function of the cement of keeping the ectoparasite attached to the host has been widely reported, this substance has proteins that act both in the host modulation and in the formation and maintenance of the feeding lesion (Mulenga et al., 2007). In this sense, the chemical composition of the cement consists of a mixture of antigenic and non antigenic proteins containing carbohydrates and lipids in the inner layers of the cone, the outer layers being formed by lipoproteins and glycoproteins (Sonenshine, 1993). Binnington (1978) studied the salivary glands of females of Boophilus microplus and demonstrated the production of: a) glycoproteins by b, c1, c2, c3 cells of type II acinus, and f cells of type III acinus, b) acid phosphatase by the three types of acini, 232 mainly by type I acinus and by d cells of type III acinus , c) protease by cell of type II acinus, d) esterase by cells of all types of acini, especially b and c cells of type II acini and e) lipoproteins by a cells of type II acinus and d and e cells of type III acinus. The tick saliva is a complex and sophisticated pharmacological arsenal effectively interacting with elements of the immune-inflammatory and hemostatic system of the host that can hold its defenses quickly since the first days of ectoparasite feeding (Ribeiro et al., 1985; Wikel, 1989; Brossard and Wikel, 1997, 2004; Francischetti et al., 2005, Steen et al., 2006). Moreover, the tick saliva immunosuppresses the host, making these ectoparasites skilled transmitters of pathogens that are transmitted through their own saliva (Wikel, 1999; Singh and Girschick, 2003; Kovár, 2004). In this sense, the saliva of ticks plays vital functions in the hemostatic, inflammatory and immune processes of the host by: a) increasing blood flow (circulation) in the bite region through the secretion of vasoactive agents; b) inoculating anticoagulants that keep the host’s blood in the fluid form; c) inhibiting the inflammatory process in the host d) immunosuppressing the host and enabling the attachment of ticks, making their rejection by the host difficult (Sauer et al., 2000). The following elements present in the saliva of ticks with pharmacological and immunological properties stand out: a) enzymes (apyrase, kininase), enzyme inhibitors, b) proteins homologous to host proteins, c) proteins that bind to immunoglobulins, d) lipocalin that bind to amines, e) agonists / antagonists of receptors, f) calcium- carrier elements (calreticulin), g) cytokine expression modulators, and h) other non-protein bioactive components such as prostaglandins (PGE2) (Steen et al., 2006; Brossard and Wikel, 2004). The action of the tick saliva is a complex process, since this mixture has quantitative and qualitative variations due to the different glandular cycle periods within the same species (Binnington, 1978; McSwain et al., 1982; Sauer et al., 1982; Shipley et al., 1993; Sanders et al., 1996; Furquim, 2007; Mulenga et al., 2007; Xiang et al., 2009) or when considering different species (Kazimírová, 2007). In addition, another important factor that contributes to the heterogeneity of the tick saliva and that should be considered is the fact that the immunereactive activity of tick-derived factors may vary depending on the host species parasitized (Lawrie et al., 1999). Harnnoi et al. (2007) demonstrated the occurrence of the expression of six types of metalloproteases along the glandular cycle of Haemaphysalis longicornis. In addition, Oliveira et al. (2011) detected the presence of molecules of non protein origin, prostaglandin (PGE2) and purine nucleoside adenoside (Ado), with strong immunomodulatory properties in the saliva of R. sanguineus and found that isolated molecules have different ways of action, whereas when combined, their action becomes enhanced. Moreover, some elements produced by the salivary glands of ticks are likely to have more than one biological activity, for example, molecules that inhibit coagulation and enhance vasodilation contribute to the formation of fixation and feeding lesion, anti-inflammatory and immunosuppressive molecules those reduce host defenses impairing the feeding of ticks (Wikel, 1996). The bioactive molecules present in the saliva of ticks of different species and genera are: apyrase, which inhibits platelet aggregation through the hydrolysis of ATP and ADP into AMP and orthophosphate (Titus and Ribeiro, 1990; Kazimírová, 2008), and prevents neutrophil aggregation and degranulation of mastocytes (Ribeiro et al., 1985). Prostaglandins (PGs), found in high concentrations in the saliva of some species of ticks (Bowman et al., 1996) such as prostaglandin E (PGE ), with anti-hemostatic, vasodilator and immunosuppressive activity (Bowman et al., 1996), which inhibit platelet aggregation and cause vasodilation (Champagne, 1994; Ribeiro et al., 1985; Kazimírová, 2008), suppress the production of interferon (IFN)-γ (Hasler et al., 1983; Betz and Fox, 1991) and interleukin (IL)-2 (Hasler et al., 1983; Betz and Fox, 1991; Krause and Deutsch, 1991) and inhibit the bioactivity of IL-2 in cells that dependent on this cytokine by reducing the expression of IL- 2 receptors in these cells (Krause and Deutsch, 1991) - thus, prostaglandins can inhibit the function of T lymphocytes (Singh and Grischick, 2003), and in Ixodes dammini, inhibit IL-2 production by these lymphocytes (Ribeiro and Spielman, 1986); prostacyclin (PGI ), found in the saliva of I. dammini, which blocks platelet aggregation, inhibits degranulation of mastocytes and induces vasodilation (Ribeiro and Spielman, 1986; Kazimírová, 2008). Elements that in Dermacentor andersoni act in factors V and VII inhibiting intrinsic (activated tissue factor) and extrinsic pathways (activated collagen) of the blood coagulation cascade (Gordon and Allen, 1991). Peptides found in the saliva of Ornithodoros savigny also inhibit the extrinsic pathway of the coagulation cascade (Ehebauer et al., 2002). Variegin found in the saliva of Amblyomma variegatum, which is a thrombin inhibitor (Koh, 2007). Anti-coagulant, which in R. appendiculatus inhibits the activity of factor Xa or other components of the prothrombinase complex (Limo et al., 1991). Another factor Xa inhibitor, TAP protein, was found both in the saliva of O. moubata (Waxman et al., 1990) and in O. Savigny (Joubert et al., 1998). Kininase, found in I. dammini, has the capacity to act in the cleavage of bradykinin (enhanced by PGE 2) (Ribeiro et al., 1985) and reduce skin irritation (itching) caused by this substance, leading to reduced removal of ticks by self-cleaning mechanism through licking. Molecules with anti- chemokine activity in adult ticks of the species R. sanguineus, which act against human chemokines CXCL8, CCL2, CCL3, CCL5, and CCL11 (Vancová et al., 2010). According to these authors, males of I. ricinus have molecules that act against these chemokines, while in females of the same species, no activity against chemokines CCL5 and CCl11 was detected (Vancová et al., 2010). Elements that bind to growth factors transforming them. In A. variegatum, these elements react with growth 2 2 2 233 factor-β (TGF-β1), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF-2) and hepatocyte growth factor (HGF), In D. reticulatus and R. appendiculatus with TGF-β1, FGF-2 and HGF and in I. ricinus and I. scapularis with PDGF (Hajinická et al., 2010). Peptides found in I. scapularis are potent inhibitors of the complement system (Tyson et al., 2007). Calcium-binding proteins (calreticulins), whose functions in the parasite-host relationship would facilitate feeding through their actions in the immune system, immunosuppressive and antihemostatic (Jaworski et al., 1995; Brossard and Wikel, 2004; Jittapalapong et al., 2008; Steen et al., 2006). Lipocalins, present both in ixodid and argasids, act in the modulation of the immune response by inhibiting platelet (Keller et al., 1993) or complement aggregation (Nunn et al., 2005; Mans and Ribeiro, 2008a), inflammation through association with histamine, serotonin, leukotrienes C4, D4, E4 (Paesen et al., 1999; Sangramnatdej et al., 2002; Mans and Ribeiro, 2008b; Mans et al., 2008c) and induction of toxicoses (Mans et al., 2001, 2002, 2003). Metalloproteases detected in the saliva of I. scapularis with anti-fibrinogen activity (Francischetti et al., 2003). Peptides that form and maintain feeding lesion (Mulenga et al., 2007). Elements that are potent inhibitors of angiogenesis and proliferation of endothelial cells (Francischetti et al., 2005). Anti-inflammatory proteins that bind to lipocalin and histamines (Mulenga et al., 2007). Also with regard to the biochemical and functional complexity of the saliva, Ribeiro (1987) reported that the pharmacology of tick saliva can adapt to specific homeostatic defenses of the host. In this sense, Furquim et al. (2011) demonstrated that the secretory behavior of the salivary glands of females of R. sanguineus is modified according to the resistance of the host through immunization. These authors found that the glandular secretion of these females showed increased amounts of many components such as proteins, lipids, polysaccharides, acid phosphatase and calcium (probably calreticulin), which enhanced the pharmacological action and biochemical complexity of the saliva produced by them, thereby modifying its action on the parasite-host relationship. Resistance acquisition of hosts In ticks, the salivary glands are important sites for producing antigens (Wikel et al., 1978; Gill et al., 1986; Almeida et al., 1994; Ferreira et al., 1996; Szabó and Bechara, 1997; Jittapalapong et al., 2000a; Nunes et al., 2011). Therefore, after the first contact of these ectoparasites with some hosts, the latter develop resistance (Wikel et al., 1978; Gill et al., 1986; Jittapalapong et al., 2000a, Zhou et al., 2006). In this sense, many studies have been carried out to verify the acquisition of resistance by hosts when they are immunized by successive infestations (Jittapalapong et al., 2000a, b; Monteiro et al., 2008, 2011; Caperucci et al., 2009, 2010; Veronez et al., 2010; Nunes et al., 2011) or by inoculation of extracts made of whole ticks (or parts of them) (Wikel, 1981; Ferreira et al., 1996; Szabó and Bechara, 1997; Jittapalapong et al., 2000a, b, 2008). In relation to the modulating capacity of tick saliva, it is known that this mixture acts on hosts affecting the proliferation of lymphocytes (Kopecky et al., 1999), decreasing the oxidative activity of macrophages (Kuthejlova et al., 2001), inhibiting neutrophils, including their oxidative and phagocytic activity (Ribeiro et al., 1990), inhibiting the activity of "natural killer-NK" cells (Kubes et al., 1994), reducing the development of the primary IgM response (Fivaz, 1989; Wikel, 1985), which remains evident for a few days after the infestation (Wikel, 1985), and decreasing cytokine production by Th1 lymphocytes (IL-2 and IFN-γ) and cytokines of macrophages, while increasing the production of cytokines by Th2 lymphocytes (IL-4, IL-5 and IL-10) (Wikel, 1999), in order to influence the class of immunoglobulin produced, causing the host to the preferential production of IgG1 and IgE immunoglobulins instead of IgG2 (Wikel, 1996). Cytokines IL-2 and IFN-γ are vital to the development of an effective immune response in the attachment and feeding lesion of the tick, including the recruitment, activation and proliferation of immunocompetent cells, thereby mediating an inflammatory response to the ectoparasite (Singh and Grischick, 2003). The acquisition of resistance by hosts is measured analyzing food and reproductive parameters of ticks infesting animals previously immunized (Wikel, 1981; Szabó and Bechara, 1997; Jittapalapong et al., 2000b), as well as analyzing the impact of this resistance on the salivary glands (Sanders et al., 1996; Jittapalapong et al., 2008; Furquim et al., 2011; Nunes et al., 2011) and intestine (Caperucci et al., 2009, 2010; Veronez et al., 2010) of different species. According to Wikel (1981) and Jittapalapong et al. (2000b, 2008), immunization obtained from antigens derived from salivary glands would stimulate the host immune response that would affect ticks of subsequent infestations due to the direct action of resistance acquired by the host in the secretory cycle of the salivary glands, reducing the efficiency of the feeding process and pathogen transmission by ticks (Jittapalapong et al., 2008). Considering that ticks are able to modulate local hemostatic reactions in the host, this ability can be affected by the immune status (resistance) of the host. In resistant hosts, large amounts of inflammatory cells are recruited and the expression of anti-coagulant molecules in the salivary glands of ticks is reduced, and this glandular alteration may hinder the consumption of blood by ticks (Carvalho et al., 2010). Recent studies have shown that the saliva of different tick species, among them R. sanguineus, modulates different steps of the biology of dendritic cells, such as maturation and migration (Oliveira et al., 2008, 2010). Anticoagulant proteins have been identified in the saliva of ticks such as Boophilina (obtained from the saliva of B. microplus) (Macedo- Ribeiro et al., 2008) and ixolaris and penthalaris (obtained from the saliva of I. scapularis) (Francischetti et al., 2002, 2004). According to Turner et al. (2002), much information can be obtained on the resistance 234 Table 1 Examples of bioactive components in tick saliva Tick species Molecule name Target/ Function Reference Ticks in general Salp15 (Anti-alarmin) Chemotactic properties of Chemokines Marchal et al., 2010 Salp 25 Antioxidant Kovar, 2004 MIF homologue (cytokine homologue) Inhibits the migration of human macrophages similarly of humam MIF Kovar, 2004 Ixodidae HBPs (lipocalins with 1 or 2 binding sites) Suppress inflammation by hystamin or serotonin binding Kovar, 2004 Hyalomma asiaticum BIF Inhibits LPS-induced proliferation of B-Cells Yu et al., 2006 Ixodes TSLPI Lectin pathway inhibitor Schuijt et al., 2011 PGs Inhibits lymphocytes L2 Ribeiro and Splielman, 1986 Isac Alternate complement pathway, interacts with C3 convertase Valenzuela et al., 2000 Salp20 C3 convertase Tyson et al., 2007 Salp15 Impairs IL-2 production and T- Cell proliferation; binds Borrelia burgdorferi OspC, protects the spirochete from antibody- mediated killing Ramamoorthi et al., 2005 IL-2 binding protein Inhibits proliferation of human T- Cells and CTLL2 Cells Gillespie et al., 2001 Ixodes scapularis Sialostatin L Inhibits cathepsin L activity Kotsyfakis et al., 2006 BIP Inhibitorof B-Cell proliferation Hannier et al., 2004 Iris Modulates T-lymphocytes and macrophage responsiveness, induce T-h2 type responses; inhibitor of homeostasis Leboulle et al., 2002 Ixodes ricinus IRAC I, II, Isac paralogues Alternate complement pathway, interacts with C3 convertase Daix et al., 2007 Ornithodoros moubata OMCI C5, prevention of interaction C5 with C5 convertase Nunn et al., 2005 Evasin-1 binds Chemokines CCL3, CCL4 and CCL18 Frauenschuh et al., 2007 Rhipicephalus sanguineus PGE2 Modulations of DCs Oliveita et al., 2011 235 acquired by hosts sensitized to different tick species or even to the same species, because immunosuppressive molecules synthesized by the salivary glands are differentially expressed during tick feeding. In addition, the salivary glands of different species have different antigens, in quantities and concentrations also different (Jaworski et al., 1990; Inokuma et al., 1994). Data are summarized in Table 1. Therapeutic properties and prospects of tick saliva The saliva of ticks has several types of molecules that modulate the immune-inflammatory and hemostatic system of their hosts (Wikel and Bergman, 1997; Steen at al., 2006; Hajnická et al., 2011). This complex mixture is considered to be a potential reservoir of multifunctional molecules, i.e., the saliva of these ectoparasites, as well as the saliva of hematophagous organisms in general has bioactive compounds of great interest (Batista et al., 2010). Thus, tick saliva has been the subject of different studies due to the great interest in the identification and isolation of bioactive molecules with vasodilating, anti-inflammatory, immunosuppressive and anticoagulant activity (Oliveira et al., 2010). The tick saliva has presented mitigating action of angiogenesis (Francischetti et al., 2005), as well as anti-tumor properties (Simons et al., 2011). In relation to the bioactive molecules present in the saliva of ticks, the evasin-1, a chemokine binding protein is used in the idiopathic pulmonary fibrosis therapy (Russo et al., 2011) a protein recently found in the saliva of A. cajennense that acts in the coagulation process, also showed cytotoxic activity in different tumor cells, among them pancreatic cells and melanomas (Chudzinski- Tavassi et al., 2010). The effects of crude saliva are also promising, since it triggered cell death and morphological changes in human melanoma cells (SK-MEL-28) and human pancreatic carcinoma (MIA PaCa-2), without causing changes in normal human fibroblasts exposed to it (Simons et al., 2011). Previous results have shown that molecules present in extracts of the salivary glands of R. appendiculatus and A. variegatum were able to hold the growth of human HeLa cells (cervical cancer cells) through an apoptotic process (Kazimírová et al., 2008). Thus, ticks seem to be a source of bioactive molecules with great potential for the treatments for some diseases, including cancer, because as already mentioned, among the known species of ticks, as well as among genera, there are differences in bioactive compounds present in their salivary glands (Kazimírová, 2008). Moreover, the acquisition of resistance by the host can affect the biochemical composition of the salivary glands / saliva of ectoparasites that feed on them. This change becomes an additional factor that contributes to the quantitative and qualitative variation of bioactives found in the saliva of ticks (Furquim et al., 2011). References Almeida APG, Bechara GH, Varma RMG. Cross- reactivity between hard tick antigens. Braz. J. Med. Biol. Res. 27: 697-707, 1994. Anderson JF, Magnarelli LA. Biology of ticks. Infect. Dis. Clin. North. Am. 22: 195-215, 2008. Balashov, YuS. An Atlas of Ixodid Tick Ultrastructure. In: Raikhel AS, Hoogstraal II (eds), Entomological Society of America (Special Publication), pp 99-128, 1983. Batista FC, Chudzinski-Tavassi AM, Faria F, Simons SM, Barros-Battesti DM, Labruna MB, et al. Expressed sequence tags (ESTs) from the salivary glands of the tick Amblyomma cajennense (Acari: Ixodidae). Toxicon 51: 823- 834, 2008. Bergman DK, Palmer MJ, Caimano MJ, Radolf JD, Wikel SK. Isolation and molecular cloning of a secreted immunosuppressant protein from Dermacentor andersoni salivary gland. J. Parasitol. 86: 516-525, 2000. Betz M, Fox BS. Prostaglandin E2 inhibits production of Th1 lymphokines but not of Th2 lymphokines. J. Immunol. 146: 108-113, 1991. Binnington KC. Sequential changes in salivary gland structure during attachment and feeding of the cattle tick Boophilus microplus. Int. J. Parasitol. 8: 97-115, 1978. Bowman AS, Dillwith JW, Sauer JR. Tick salivary prostaglandins: presence, origin and significance. Parasitol. Today 12, 388-396, 1996. Bowman AS, Sauer JR. Tick salivary glands: Function, physiology and future. Parasitology 129: S67-S81, 2004. Brossard M, Wikel SK. Immunology of interactions between ticks and hosts. Med. Vet. Entomol. 11: 270-276, 1997. Brossard M, Wikel SK. Tick immunobiology. Parasitology 129: S161-S176, 2004. Champagne DE. The role of salivary vasodilators in bloodfeeding and parasite transmission. Parasitol. Today 10: 430-433, 1994. Caperucci D, Bechara GH, Camargo-Mathias MI. Histopathology and ultrastructure features of the midgut of adult females of the tick Amblyomma cajennense Fabricius, 1787 (Acari: Ixodidae) in various feeding stages and submitted to three infestations. Ultrastr. Pathol. 33: 249-259, 2009. Caperucci D, Bechara GH, Camargo-Mathias MI. Ultrastructure features of the midgut of the female adult Amblyomma cajennense ticks Fabricius,1787 (Acari: Ixodidae) in several feeding stages and subjected to three infestations. Micron 41: 710-721, 2010. Carvalho WA, Maruyama SR, Franzin AM, Abatepaulo ARR, Anderson JM, Ferreira BR, et al. Rhipicephalus (Boophilus) microplus: Clotting time in tick-infested skin varies according to local inflammation and gene expression patterns in tick salivary glands. Exp. Parasitol. 124: 428-435, 2010. Chudzinski-Tavassi AM, Sá-Júnior PL, Simons SM, Maria DA, Ventura JS, Batista IFC, et al. A new 236 tick Kunitz type inhibitor, Amblyomin-X, induces tumor cell death by modulating genes related to the cell cycle and targeting the ubiquitin- proteasome system. Toxicon 56: 1145-1154, 2010. Dantas-Torres F. Biology and ecology of the brown dog tick, Rhipicephalus sanguineus. Parasites & Vectors 3: 26, 2010. Daix V, Schroeder H, Praet N, Georgin JP, Chiappino I, Gillet L, et al. Ixodes ticks belonging to the Ixodes ricinus complex encode a family of anticomplement protein. Insect Mol. Biol. 16: 155-166, 2007. Ehebauer MT, Mans BJ, Gaspar AR, Neitz AW. Identification of extrinsic blood coagulation pathway inhibitors from the tick Ornithodoros savignyi (Acari: Argasidae). Exp. Parasitol. 101: 138-148, 2002. Fawcett DW, Binnington KC, Voight WR. The cell biology of the ixodid tick salivary gland. In: Sauer JR, Hair JA (eds), Morphology, physiology and behavioral biology of ticks, Ellis Horwood, pp 22-45, 1986. Feldman-Muhsam B, Borut S, Saliternik-Givant S. Salivary secretion of the male tick during copulation. J. Insect Physiol. 16: 1945-1949, 1970. Ferreira BR, Machado RZ, Bechara GH. Western blot analysis of tick antigens from a Rhipicephalus sanguineus unfed larval extract and identification of antigenic sites in tick sections using immunohistochemistry. A comparative study between resistant and susceptible host species. Vet. Parasitol. 62: 161-174, 1996. Fivaz BH. Immune suppression induced by the brown ear tick Rhipicephalus sanguineus Neuman, 1901. J. Parasitol. 75: 946-952, 1989. Francischetti IM, Valenzuela JG, Anderson JF, Mather TN, Ribeiro JM. Ixolaris, a novel recombinant tissue factor pathway inhibitor (TFPI) from the salivary gland of the tick Ixodes scapiularis identification of factor X and factors Xa as scaffolds for the inhibition of factor VIIa/ tissue factor complex. Blood 99: 3602-3612, 2002. Francischetti IM, Mather TN, Ribeiro J. MCloning of a metalloprotease and characterization of gelatinase and fibrin (ogen)lytic activities in the saliva of the lyme disease tick vector Ixodes scapularis. Biochem. Biophys. Res. Commun. 13: 869-875, 2003. Francischetti IM, Mather TN, Ribeiro JM. Penthalaris a novel recombinant five-Kunitz tissue factor pathway inhibitor (TFPI) from the salivary gland of the tick vector of Lyme disease, Ixodes scapularis. Thrombosis & Haemostasis 91: 886-898, 2004. Francicchetti IMB, Mather TN, Ribeiro JNC. Tick saliva is a potent inhibitor of endothelial cell proliferation and angiogenesis. Thrombosis & Haemostasis, 94: 167-174, 2005. Francischetti IMB, Sá-Nunes A, Mans BJ, Santos IM, Ribeiro JMC. The role of saliva in tick feeding. Front. Biosci. 14: 2051-2088, 2010. Frauenschuh A, Power CA, Déruaz M, Ferreira BR, da Silva J, Teixeira MM, et al. Molecular cloning and characterization of a highly selective chemokine-binding protein from the tick Rhipicephalus sanguineus. J. Biol. Chem. 282: 27250-27258, 2007. Furquim KCS. Estudo das glândulas salivares de fêmeas e de machos de carrapatos Rhipicephalus sanguineus (Latreille, 1806) (Acari, Ixodidae): caracterização do ciclo secretor com ênfase no processo de degeneração. Tese de Doutorado, Instituto de Biociências, UNESP, Rio Claro, Brasil, 2007. Furquim KCS, Bechara GH, Camargo-Mathias MI. Death by apoptosis in salivary glands of females of the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae). Exp. Parasitol. 119: 152-163, 2008a. Furquim KCS, Bechara GH, Camargo-Mathias MI. Markers of cell death in salivary glands of males of the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari, Ixodidae). Parasitol. Int. 57: 396-404, 2008b. Furquim KCS, Bechara GH, Camargo-Mathias MI. Morpho-histochemical characterization of salivary gland cells of males of the tick Rhipicephalus sanguineus (Acari: Ixodidae) at different feeding stages: description of new cell types. Exp. Appl. Acarol. 50: 59-70, 2010. Furquim KCS, Camargo-Mathias MI, Hebling LMGF, Roma GC, Bechara GH. Ticks’ response to feeding on host immunized with glandular extracts of Rhipicephalus sanguineus females fed for 2, 4, and 6 days. I. Inactivity or early degeneration of salivary glands? Parasitol. Res. 109: 147-162, 2011. Gill HS, Bois R, Ross CA. Isolation and characterization of salivary antigens from Hyalomma anatolicum. Parasite Immunol. 8: 11-25, 1986. Gill HS, Walker AR. The salivary glands of Hyalomma anatolicum anatolicum: nature of salivary gland components and their role in tick attachment and feeding. Int. J. Parasitol. 18: 83-93, 1987. Gillespie RD, Dolan MC, Piesman J, Titus RG. Identification of an IL-2 binding protein in the saliva of the Lyme disease vector tick Ixodes scapularis. J. Immunol. 166: 4319-4326, 2001. Gordon JR, Allen JR. Factor V and VII anticoagulant activities in the salivary glands of feeding Dermacentor andersoni ticks. J. Parasitol. 77: 167-170, 1991. Hajnická V, Vancová I, Slovák M, Kocáková P, Nuttall PA. Ixodid tick salivary gland products target host wound healing growth factors. Int. J. Parasitol. 41: 213-223, 2011. Hannier S, Liversidge J, Sternberg JM, Bowman AS. Characterization of the B-cell inhibitory protein factor in Ixodes ricinus tick saliva: a potencial role in enhanced Borrelia burgdoferi transmission. Immunology 113: 401-408, 2004. Harnnoy T, Sakaguchi T, Nishikawa Y, Xuan X, Fujisaki K. Molecular characterization and comparative study of 6 salivary gland metalloproteases from the hardy tick, 237 Haemaphysalis longicornis. Comp. Biochem. Physiol. 147B: 93-101, 2007. Hasler F, Bluestein HG, Zvaifler NJ, Epstein LB. Analysis of the defects responsible for the impaired regulation of Epstein-Barr virus- induced B cell proliferation by rheumatoid arthritis lymphocytes. 1. Diminished gamma interferon production in response to autologous stimulation. J. Exp. Med. 157: 173- 188, 1983. Inokuma H, Kemp DH, Willadsen P. Prostaglandin E2 production by the cattle tick (Boophilus microplus) into feeding sites and its effect on the response of bovine mononuclear cells to mitogen. Vet. Parasitol. 53: 293-299, 1994. Jaworski DC, Muller MT, Simmen FA, Needham GR. Amblyomma americanum: identification of tick salivary gland antigens from unfed and early feeding females with comparasions to Ixodes dammini and Dermacentor variabilis. Exp. Parasitol. 70: 217-226, 1990. Jaworski DC, Simmen FA, Lamoreaux W, Coons LB, Muller MT, Needham GR. A secreted calreticulin protein in ixodid tick (Amblyomma americanum) saliva. J. Insect Physiol. 41: 369- 375, 1995. Jittapalapong S, Phichitrasilp T, Chanphao H, Rerkamnuychoke W, Stich RW. Immunization with tick salivary gland extracts. Impact on salivary gland ultrastructure in Rhipicephalus (Boophilus) microplus collected from immunized naturally infested cattle. Anim. Biodiv. Emerg. Dis. 1149: 200-204, 2008. Jittapalapong S, Stich RW, Gordon JC, Wittum TE, Barriga OO. Performance of female Rhipicephalus sanguineus (Acari: Ixodidae) fed dogs exposed to multiple infestations or immunization with tick salivary gland or midgut tissues. J. Med. Entomol. 37: 601-611, 2000a. Jittapalapong S, Stich RW, Gordon JC, Bremer CA, Barriga OO. Humoral Immune Response of Dogs Immunized with Salivary Gland, Midgut, or Repeated Infestations with Rhipicephalus sanguineus. Ann. NY Acad. Sci. 916: 283-288, 2000b. Joubert AM, Louw AI, Joubert F, Neitz AWH. Cloning nucleotide sequence and expression of the gene encoding factor Xa inhibitor from the salivary glands of the tick Ornithodoros savignyi. Exp. Appl. Acarol. 22: 603-610, 1998. Kaewhom P, Stich RW, Needham GR, Jittapalapong S. Molecular analysis of calreticulin expressed in salivary glands of Rhipicephalus (Boophilus) microplus indigenous to Thailand. Anim. Biodiv. Emerg. Dis. 1149: 53-57, 2008. Kaufman WR, Sauer JR. Ion and water balance in feeding ticks: mechanism of tick excretion. In: Obenchain FD, Galun R (eds), Physiology of ticks. Pergamon Press, pp 213-243, 1982. Kazimírová M. Pharmacologically active compounds in tick salivary glands. Adv. Arachnol. Dev. Biol. 12: 281-296, 2008. Keirans JE, Durden LA. Tick systematics and identification. In: Goodman JL, Dennis DT, Sonenshine DE (eds), Tick-borne diseases of humans, ASM Press, pp 123-140, 2005. Keller PM, Waxman L, Arnold BA, Schultz LD, Condra C, Connolly TM. Cloning of the cDNA and expression of moubatin, an inhibitor of platelet aggregation. J. Biol. Chem. 268: 5450- 5456, 1993. Koh CY, Kazimirova M, Trimnell A, Takac P, Labuda M, Nuttall P, et al. Variegin, a novel class of fast and tight-binding thrombin inhibitor from the tropical bont tick. J. Biol. Chem. 282: 29101-29113, 2007. Konnai S, Nishikado H, Yamada S, Imamura S, Ito T, Onuma M, et al. Molecular identification and expression. Analysis of lipocalins from blood feeding taiga tick, Ixodes persulcatus schulze. Exp. Parasitol. 127: 467-474, 2011. Kopecky J, Kuthejlova M, Pechova J. Salivary gland extract from Ixodes ricinus ticks inhibits production of interferon-gama by the upregulation of interleukin-10. Parasite Immunol. 21: 351-356, 1999. Kotsyfakis M, Sa-Nunes A, Francischetti IM, Mather TN, Andersen JF, Ribeiro JMC. Antiinflammatory and immunosuppressive activity of sialostatin L, a salivary cystatin from the tick Ixodes scapularis. J. Biol. Chem. 281: 26298-26307, 2006. Kovár L. Tick saliva in anti-tick immunity and pathogen transmission. Folia Microbiol. 49: 327-336, 2004. Krause DS, Deutsch S. Cyclic AMP derectly inhibits IL-2 receptor expression in human T cells: expression of both p55 and p75 subunits is affected. J. Immunol. 146: 2285-2296, 1991. Kubes M, Fuchsberger N, Labuda M, Zuffova E, Nuttall PA. Salivary gland extracts of partially fed Dermacentor reticulatus ticks decrease natural killer cell activity in vitro. Immunology 82: 113-116, 1994. Kuthejlova M, Kopecky J, Stepanova G, Macela A. Salivary gland extract inhibits killing of Borrelia afzelli spirochetes by mouse macrophages. Infect. Immun. 69: 575-578, 2001. Labruna MB, Ahid SMM, Soares HS, Suassana ACD. Hyperparasitism in Amblyomma rotundatum (Acari: Ixodidae). J. Parasitol. 93: 1531-1532, 2007. Leboulle G, Crippa M, Decrem Y, Mejri N, Brossard M, Bollen A, et al. Characterization of a novel salivary immunosuppressive protein from Ixodes ricinus ticks. J. Biol. Chem. 277: 10083- 10089, 2002. Limo MK, Voigt WP, Tumbo-Oeiri AG, Ole-Moi Yoi OK. Purification and characterization of an anticoagulant from the salivary glands of the ixodid tick Rhipicephalus appendiculatus. Exp. Parasitol. 72: 418-429, 1991. Lawrie CH, Randolph SE, Nuttall PA. Ixodes ticks: serum species sensitivity of anticomplement activity. Exp. Parasitol. 93: 207-214, 1999. Macedo-Ribeiro S, Almeida C, Calisto BM, Friedrich T, Mentele R, Sturzebecher J, et al. Isolation cloning and structural characterization of boophilin a multifunctional Kunitz-type proteinase inhibitor from the cattle tick. PLoS One 3, e1624, 2008. Mans BJ, Venter JD, Vrey PJ, Louw AI, Neitz AW. Identification of pupative proteins involved in 238 granule biogenesis of tick salivary glands. Electrophoresis 22: 1739-1746, 2001. Mans BJ, Steinmann CM, Venter JD, Louw AI, Neitz AW. Pathogenic mechanisms of sand tampan toxicoses induced by the tick, Ornithodoros savignyi. Toxicon 40: 1007-1016, 2002. Mans BJ, Louw AI, Neitz AWH. The major tick salivary gland proteins and toxins from the soft tick, Ornithodoros savignyi, are part of the tick lipocalin family: Implications for the origins of tick toxicoses. Mol. Biol. Evol. 20: 1158-1167, 2003. Mans BJ, Ribeiro JM. Function mechanism and evolution of the moubatin-clade of soft tick lipocalins. Insect Biochem. Mol. Biol. 38: 841- 852, 2008a. Mans BJ, Ribeiro JM. A novel clade of cysteinyl leukotriene scavengers in soft ticks. Insect Biochem. Mol. Biol. 38: 862-870, 2008b. Mans BJ, Ribeiro JM, Andersen JF. Structure, function and evolution of biogenic amine- binding proteins in soft ticks. J. Biol. Chem. 283: 18721-18733, 2008c. Marchal M, Schramm F, Kern A, Luft BJ, Yang X, Schuijt T, et al. Antialarmin effect of tick saliva during the transmission of Lyme disease. Infect. Immun. 79: 774-785, 2011. McSwain JL, Essemberg RC, Sauer JR. Protein changes in the salivary glands of the female lone star tick, Amblyomma americanum, during feeding. J. Parasitol. 68: 100-106, 1982. Monteiro GER, Bechara GH. Cutaneus basophilia in the resistance of goats to Amblyomma cajennense nymphs after repeated infestations. Ann. NY Acad. Sci. 1149: 221-225, 2008. Monteiro GER, Bechara GH, Franzin AM, Miranda Santos IKF. Antigen-presenting in draining lymph nodes of goads repeatedly infested by the Cayenne tick Amblyomma cajennense nymphs. Exp. Appl. Acarol. 53: 63-69, 2011. Mulenga A, Blandon M, Khumthong R. The molecular basis of the Amblyomma americanum tick attachment phase. Exp. Appl. Acarol. 41: 267-287, 2007. Nunn MA, Sharma A, Paesen GC, Adamson S, Lissinna O, Willis AC, et al. Complemente inhibitor of C5 activation from the soft tick Ornithodoros moubata. J. Immunol. 174: 2084- 2091, 2005. Nunes PH, Bechara GH, Camargo-Mathias MI. Morphological changes in the salivary glands of Amblyomma cajennense females (Acari: Ixodidae) in different feeding stages on rabbits at first infestation. Exp. Appl. Acarol. 45: 199- 209, 2008. Nunes PH, Bechara GH, Camargo-Mathias MI. Secretory process of salivary glands of female Amblyomma cajennense (Acari: Ixodidae) ticks fed on resistant rabbits. Exp. Appl. Acarol. 53: 179-187, 2011. Oliveira CJ, Cavassani KA, Moré DD, Garlet GP, Aliberti JC, Silva JS, et al. Tick saliva inhibits the chemotactic function of MIP-1 and selectively impairs chemotaxis of immature dendritic cells by down-regulating cell-surface CCR5. Int. J. Parasitol. 38: 705-716, 2008. Oliveira CJ, Carvalho WA, Garcia GR, Gutierrez FR, de Miranda Santos IK, Silva JS, et al. Tick saliva induces regulatory dendritic cells: MAP- kinases and Toll-like receptor-2 expression as potential targets. Vet. Parasitol. 167: 288-297, 2010. Oliveira JC, Sá-Nunes A, Francischetti IMB, Carregaro V, Anatriello E, Silva JS, et al. Deconstructing saliva. Non-protein Molecules with potente immunomodulatory properties. J. Biol. Chem. 286: 10960-10969, 2011. Paesen GC, Adams PL, Harlos K, Nuttall PA, Stuart DI. Tick histamine-binding proteins: isolation, cloning, and three-dimensional structure. Mol. Cell 3: 661-671, 1999.573-577, 2005. Ramamoorthi N, Narasimhan S, Pal U, Bao F, Yang XF, Fish D, et al. The Lyme disease agent exploits a tick protein to infect the mammalian host. Nature 436: Ribeiro JMC, Makoul GT, Levine J, Robinson DK, Spilman A. Antihaemostatic, anti-inflammatory and immunosupressive properties of the saliva of a tick, Ixodes dammini. J. Exp. Med. 161: 332-344, 1985. Ribeiro JMC, Spielman A. Ixodes dammini: salivary anaphylatoxin inactivating activity. Exp. Parasitol. 62: 292-297, 1986. Ribeiro JMC, Weiss JJ, Telford SR. Saliva of the tick Ixodes dammini inhibits neutrophil function. Exp. Parasitol. 70: 382-388, 1990. Russo RC, Alessandri AL, Garcia CC, Cordeiro FB, Pinho V, Cassali GD, et al. Therapeutic Effects of Evasin-1, a Chemokine Binding Protein, in Bleomycin-Induced Pulmonary Fibrosis. American Journal of Respiratory Cell Mol. Biol. 45: 72-80, 2011. Sanders ML, Scott AI, Glass GE, Schwartz BS. Salivary gland changes and host antibody responses associated with feeding of male lone star ticks (Acari: Ixodidae). J. Med. Entomol. 33: 628-634, 1996. Sangramnatdej S, Paesen GC, Slovak M, Nuttall PA. A high affinity serotonin- and histamine-binding lipocalin from tick saliva. Insect Mol. Biol. 11: 79-86, 2002. Sauer JR, Essenberg RC, Bowman AS. Salivary glands in ixodid ticks: control and mechanism of secretion. J. Insect Physiol. 46: 1069-1078, 2000. Schuijt TJ, Coumou J, Narasimhan S, Dai J, Deponte K, Wounters D, et al. A tick mannose- binding lectin inhibitor interferes with the vertebrate complement cascade to enhance transmission of the lyme disease agent. Cell Host Microb. 18: 136-146, 2011. Shipley MM, Dillwith JW, Bowman AS, Essemberg RC, Sauer JR. Changes in lipids of the salivary glands of the lone star tick, Amblyomma americanum, during feeding. J. Parasitol. 79: 834-842, 1993. Simons SM, Sá-Júnior PL, Faria F, Batista IFC, Barros-Battesti DM, Labruna MB, Chudzinski- Tavassi, A.M. The action of Amblyomma cajennense tick saliva in compounds of hemostatic system and cytotoxicity in tumor cell lines. Biomed. Pharmacother. 65 : 443-450, 2011. 239 http://lattes.cnpq.br/2382374201685423 http://lattes.cnpq.br/2194016802158346 http://www.ncbi.nlm.nih.gov/pubmed?term=%22Nunes%20PH%22%5BAuthor%5D http://www.ncbi.nlm.nih.gov/pubmed?term=%22Bechara%20GH%22%5BAuthor%5D http://www.ncbi.nlm.nih.gov/pubmed?term=%22Camargo%20Mathias%20MI%22%5BAuthor%5D http://www.ncbi.nlm.nih.gov/pubmed/clipboard http://www.ncbi.nlm.nih.gov/pubmed/19836139 http://www.ncbi.nlm.nih.gov/pubmed/19836139 http://www.ncbi.nlm.nih.gov/pubmed/19836139 http://www.ncbi.nlm.nih.gov/pubmed/19836139 Singh SK, Girschick HJ. Tick-host interactions and their immunological implications in tick-borne diseases. Curr. Sci. 85: 1284-1298, 2003. Waxman L, Smith DE, Arcuri KE, Vlasuk GP. Tick anticoagulant peptide (TAP) is a novel inhibitor of blood coagulation factor Xa. Science 248: 593-596, 1990. Sonenshine DE. Biology of ticks. Oxford University Press, 1991. Wheeler CM, Coleman JL, Benach JL. Salivary gland antigens of Ixodes dammini are glycoproteins that have interspecies cross- reactivity. J. Parasitol. 77: 965-973, 1991. Steen NA, Barker SC, Alewood PF. Proteins in the saliva of the Ixodida (ticks): Pharmacological features and biological significance. Toxicon 47: 1-20, 2006. Wikel SK, Graham JE, Allen JR. Acquired resistance to ticks. IV. Skin reactivity and in vitro lymphocyte responsiveness to salivary gland antigen. Immunology 34: 257-263, 1978. Szabó MPJ, Bechara GH. Immunization of dogs and guinea pigs against Rhipicephalus sanguineus ticks using gut extract. Vet. Parasitol. 68: 283- 294, 1997. Titus RG, Ribeiro JMC. The role of vector saliva in transmission of arthropod-borne desease. Parasitol. Today 6: 157-160, 1990. Wikel SK. The induction of host resistance to tick infestation with salivary gland antigen. Am. J. Trop. Med. Hyg. 30: 284-288, 1981. Turni C, Lee RP, Jackson LA. Effect of salivary gland extracts from the tick, Boophilus microplus, on leucocytes from Brahman and Hereford cattle. Parasite Immunol. 24: 355-361, 2002. Wikel SK. Effects of tick infestation on the plaque- forming cell response to a thymic dependent antigen. Ann. Trop. Med. Parasitol. 79: 195-198, 1985. Wikel SK. Host immunity to ticks. Annu. Rev. Entomol. 41: 1-22, 1996. Tyson K, Elkins C, Patterson H, Fikrig E. Biochemical and functional characterization of Salp20, as Ixodes scapularis tick salivary protein thar inhibits the complement pathway. Insect Mol. Biol. 16: 469-479, 2007. Wikel SK, Bergman DK. Tick host immunology: Significant advances and challenging opportunities. Parasitol. Today 13: 383-389, 1997. Valenzuela JG, Charlab R, Mather TN, Ribeiro JM. Purification, cloning, and expression of a novel salivary anticomplement protein from the tick Ixodes scapularis. J. Biol. Chem. 275: 18717- 18723, 2000. Wikel SK. Tick modulation of host immunity: an important factor in pathogen transmission. Int. J. Parasitol. 29: 851-859, 1999. Xiang F, Zhang J, Zhou Y, Li Z, Gong H, Zhou J. Proteomic analysis of proteins in the salivary glands of the fed and unfed female tick Rhipicephalus haemaphysaloides. Agricultural Sciences in China, 8: 121-127, 2009. Vancová I, Hajnická V, Slovák M, Nuttall PA. Anti- chemokine activities of ixodid ticks depend in tick species developmental stage, and duration of feeding. Vet. Parasitol. 167: 274-278, 2010. Yu D, Liang J, Yu H, Wu H, Xu C, Liu J, et al. A tick B-cell inhibitory protein from salivary glands of the hard tick Hyalomma asiaticum. Biochem. Biophys. Res. Commun. 343: 585-590, 2006. Veronez VA, Castro MB, Bechara GH, Szabó MPJ. Histopathology of Rhipicephalus sanguineus (Acari: Ixodidae) ticks fed on resistant hosts. Exp. Appl. Acarol. 50: 151-161, 2010. Zhou J, Gong H, Zhou Y, Xuan X, Fujisaki K. Identification of a glycine-rich protein from the tick Rhipicephalus haemaphysaloides and evaluation of its vaccine potential against tick feeding. Parasitol. Res. 100: 77-84, 2006. Walker A, Fletcher JD, Gill HS. Structural and histochemical changes in the salivary glands of Rhipicephalus appendiculatus during feeding. Int. J. Parasitol. 15: 81-100, 1985. 240