Bioactive Compounds in Tick and Mite Venoms (Saliva)

Abstract

Ticks and mites are bloodsucking ectoparasites containing anticoagulants as well as many other bioactive compounds. Because of their extremely small size, collection of venom (saliva) is very difficult. Therefore, the scientific study of tick and mite venoms is far less well developed than that of other venoms such as snake, scorpion, and bee. In this review article, anticoagulant components, paralytic toxins, and the effect of venom on the immune system are reviewed. Anticoagulants are discussed in three parts, namely inhibition of thrombin, inhibition of factor X activation, and effect on other blood coagulation factors. Among the venom (saliva) components, lipids, enzymes, and other bioactive components are discussed. Paralysis is discussed without further subdivision. Immunological considerations are reviewed in two ways: their effect on host immune system, and efforts to develop vaccines and toxoids. All together 142 references were quoted.

Venomous and Poisonous Australian Animals of Veterinary Importance: A Rich Source of Novel Therapeutics

“…The toxicity of ticks, which are hematophagic ectoparasites, comes from antigens in their saliva that modulate the host's immune response in order to facilitate blood feeding. Tick salivary anticoagulants are reported to act through either the inhibition of thrombin or inhibition of factor X activation [ 62 ]. Ixodes tick paralysis is a toxin-mediated type of acute flaccid paralysis caused by the presynaptic neurotoxin holocyclotoxin, which acts to inhibit acetylcholine release at the neuromuscular junction [ 63 – 65 ].…”

How do Vampires Suck Blood?

“…They act as 'local hormones' and regulate a plethora of physiological processes 31,48 . PGs are a group of well-studied blood-sucking related metabolites, and they have been discovered in many bloodsuckers, including ticks [25][26][27][28] , salmon louses 29,30 and forest leeches 31 . Among them, PGE2 is the most commonly found PGs in the secretions, and it has demonstrated prolonged parasitic feeding (anticoagulant), increased blood flow to the site of attachment (vasodilation), and/or evasion of host immune responses (immunomodulator).…”

“…It has been also reported that PGE2 could inhibit wound healing by recruiting fibroblasts to the feeding lesion 27 . In addition to PGE2, PGF2 alpha was also commonly detected in bloodsuckers with reported functions of vasodilation, platelet aggregation inhibition, anti-inflammation, and pain alleviation 25, 31 . In this study, we have detected another two PGs, i.e., PGJ2 and PGE3, in lamprey buccal gland.…”

“…3e). PGs are a group of well-studied blood-sucking related metabolites with vasodilatory and immunomodulatory capabilities, and they have been discovered in the saliva of many bloodsuckers such as tick [25][26][27][28] , salmon louse 29,30 and forest leech 31 . It is well established that there is great similarity in the salivary components among different bloodsuckers, and one consistency is the presence of PGs.…”

Vampire Venom: Vasodilatory Mechanisms of Vampire Bat (Desmodus rotundus) Blood Feeding

“…In addition, sand flies contain a potent vasodilator (maxadilan) that acts via the PAC1 receptor [21,22], and horse fly disintegrins inhibit platelet aggregation like those from snake venoms [23]. Interestingly, tick prostaglandins constrict blood vessels [24]. The maintenance of blood flow during feeding is a major rate limiting step and challenge for blood feeders to overcome.…”