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The results suggest that Wf-536 is a potentially valuable drug for preventing tumor metastasis both in monotherapy and in combination with an antineoplastic drug.

ABSTRACT. Immunological protection of hosts against tick infestation is at present the most practically sustainable alternative tick control method to the current use of acaricides that is riddled with serious limitations. The current focus of tick vaccine research is the identification, cloning and in vitro production of recombinant tick vaccine candidate antigens. We have examined a selected number of reports on the roles of parasite-encoded members of the serine proteinase inhibitor (serpin) superfamily in modulation of mammalian anti-parasite defense and developed some food for thought commentaries on the possibility of targeting this class of proteins for anti-tick vaccine development. KEY WORDS: ixodid tick, serpin, tick vaccine development.J. Vet. Med. Sci. 63(10): 1063-1069 Ixodid ticks are the most important blood feeding arthropod vectors of infectious agents to domestic livestock and wild animals, and they are second to mosquitoes as vectors of pathogens to man [37]. The livestock industry annually experiences monetary loses estimated in hundreds of millions of dollars due to direct tick feeding activities and the diseases they transmit. Suppression of tick populations remains the method of choice to reduce the tick impact on the livestock industry. Tick control is at present almost totally dependent on the use of acaricides. Limitations of this approach, such as ixodid ticks developing resistance to these chemicals and acaricidal contamination of the environment have stimulated research into alternative methods to control ticks. Among the several methods that have been considered so far [50], vaccination of hosts against ticks has been shown to be practical and sustainable. This was evidenced in a series of studies [42,57,61] leading to commercialization [62] of the first ever anti-arthropod vaccine against the cattle tick Boophilus microplus. While work on the anti-B. microplus tick vaccine is remarkably advanced and practical, studies on other major tick species such as Amblyomma, Hyalomma and Rhipicephalus are still far from being practical [30]. The focus of research in tick vaccine development at present is the identification, molecular cloning, in vitro production and characterization of tick proteins responsible for executing key roles such as acquisition and digestion of the blood meal, modulation of host immune response and pathogen transmission by ticks [30]. Figure 1 summarizes the postulated effect of tick saliva proteins on the host's immune response factors. During the long feeding periods, hard ticks provoke host immune defense which is aimed at expelling the intruding tick. In order to complete feeding successfully, ticks secrete an array of bioactive saliva proteins which modulate the host's homeostatic balance. Additionally tick gut proteins are also essential in ensuring that the imbibed blood remains in a fluid sate and available for digestion [21]. The authors of this review previously cloned and expressed in vitro two cDNAs encoding immunodominant 29 (p29) and 34 kDa (HL34) sali...

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