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The presence in nature of species with genetic resistance to ticks, or with acquired resistance after repeated tick infestations, has encouraged the scientific community to consider vaccination as an alternative to the unsustainable chemical control of ticks. After numerous attempts to artificially immunize hosts with tick extracts, the purification and characterization of the Bm86 antigen by Willadsen et al. in 1989 constituted a revolutionary step forward in the development of vaccines against ticks. Previously, innovative studies that had used tick gut extracts for the immunization of cattle against Rhipicepahalus microplus (previously named Boophilus microplus) ticks, with amazingly successful results, demonstrated the feasibility of using antigens other than salivary-gland-derived molecules to induce a strong anti-tick immunity. However, the practical application of an anti-tick vaccine required the isolation, identification, and purification of the responsible antigen, which was finally defined as the Bm86 protein. More than thirty years later, the only commercially available anti-tick vaccines are still based on this antigen, and all our current knowledge about the field application of immunological control based on vaccination against ticks has been obtained through the use of these vaccines. [ABSTRACT FROM AUTHOR]

The southern cattle fever tick (SCFT) Rhipicephalus (Boophilus) microplus , is considered the most important ectoparasite of livestock in the world because of high financial losses associated with direct feeding and transmission of the hemoparasites Babesia bovis , B. bigemina , and Anaplasma marginale. Unfortunately, SCFT in many parts of the world have evolved resistance to all market-available pesticides thus driving development of new control technologies. Vaccination against ticks using the tick gut protein Bm86 has been shown to be effective against acaricide-resistant ticks. This technique has been successfully implemented in Puerto Rico for the control of acaricide-resistant R. microplus on dairy and beef cattle. Observations from Puerto Rico indicate a potentially positive interaction between anti-tick vaccination when used in conjunction with systemic acaricide treatment. In this project, controlled animal studies were completed directly comparing efficacy of anti-tick vaccination with and without systemic acaricide. Results show that the Bm86 anti-tick vaccine in combination with the macrocyclic lactone, Moxidectin, expressed a synergistic interaction, providing greater and longer efficacy than either treatment alone. [ABSTRACT FROM AUTHOR]

Abstract: Cattle ticks, Rhipicephalus (Boophilus) spp., infestations are a major veterinary problem that impacts cattle production worldwide. Recently, vaccination has emerged as an alternative to control tick infestations that has shown the advantage of being cost-effective, avoids environmental contamination and prevents selection of drug-resistant ticks resulting from repeated acaricides applications. However, the success of vaccination is highly dependent on the availability of effective vaccines at affordable prices. Recombinant DNA technology has provided the mean for producing antigens in large quantities making possible the development and commercialization of anti-tick vaccines. In the early 1990s, a technology was developed to produce a commercial anti-tick vaccine based on the recombinant BM86 (rBM86) antigen isolated from R. (Boophilus) microplus and intracellularly expressed in Pichia pastoris. However, the technological process for its production was expensive. Herein we conducted an economical analysis of this technology in comparison with other reported processes. The results allowed the identification of critical steps in the technology and addressed research for bioprocess optimization. As a result, two alternative bioprocesses were developed to produce anti-tick vaccines based on the rBM86 protein secreted in P. pastoris and by displaying antigenic peptides on the Escherichia coli membrane (BM95-MSP1a antigen). Vaccine production costs were reduced from US$0.92/dose for the intracellular rBM86 to US$0.72/dose and US$0.56/dose for the secreted rBM86 and BM95-MSP1a, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The Rhipicephalus (Boophilus) microplus BM86 and BM95 glycoproteins are homologous proteins that protect cattle against tick infestations. In this study, we demonstrated that the recombinant chimeric protein comprising tick BM95 immunogenic peptides fused to the A. marginale MSP1a N-terminal region for presentation on the Escherichia coli membrane was protective against R. microplus infestations in rabbits. This system provides a novel and simple approach for the production of tick protective antigens by surface display of antigenic protein chimera on live E. coli and suggests the possibility of using recombinant bacterial membrane fractions for vaccination against cattle tick infestations. [Copyright &y& Elsevier]

Abstract: Dermanyssus gallinae has a worldwide distribution and is considered to be the most serious and economically significant ectoparasite affecting egg-laying poultry in Europe. Recombinant Bm86 and subolesin proteins derived from Boophilus microplus ticks and Aedes albopictus mosquitoes were used to immunise poultry in an attempt to control D. gallinae in vitro. Immunisation with subolesin and Bm86 stimulated different profiles of IgY response, whilst Bm86 but not subolesin was recognized by IgY on western blots. Orthologues for Bm86 were not found in D. gallinae by PCR, but a 150bp fragment aligned with mammalian akirin 1 and a 300bp fragment aligned with Amblyomma hebraeum were amplified by subolesin PCR. D. gallinae mortality after feeding was 35.1% higher (P= 0.009) in the Subolesin group and 23% higher (not significant) in the Bm86 compared to the Control group. Thus it can be concluded that immunisation with recombinant subolesin can stimulate a protective response in laying hens against D. gallinae. [Copyright &y& Elsevier]

Abstract: The use of RNA interference (RNAi) to assess gene function has been demonstrated in several three-host tick species but adaptation of RNAi to the one-host tick, Boophilus microplus, has not been reported. We evaluated the application of RNAi in B. microplus and the effect of gene silencing on three tick-protective antigens: Bm86, Bm91 and subolesin. Gene-specific double-stranded (dsRNA) was injected into two tick stages, freshly molted unfed and engorged females, and specific gene silencing was confirmed by real time PCR. Gene silencing occurred in injected unfed females after they were allowed to feed. Injection of dsRNA into engorged females caused gene silencing in the subsequently oviposited eggs and larvae that hatched from these eggs, but not in adults that developed from these larvae. dsRNA injected into engorged females could be detected by quantitative real-time RT-PCR in eggs 14 days from the beginning of oviposition, demonstrating that unprocessed dsRNA was incorporated in the eggs. Eggs produced by engorged females injected with subolesin dsRNA were abnormal, suggesting that subolesin may play a role in embryonic development. The injection of dsRNA into engorged females to obtain gene-specific silencing in eggs and larvae is a novel method which can be used to study gene function in tick embryogenesis. [Copyright &y& Elsevier]

The new antigen Bm95 from the cattle tick Boophilus microplus was recently isolated, cloned and expressed in the methylotrophic yeast Pichia pastoris. The recombinant protein has shown to induce protection in cattle against infestations of B. microplus under controlled and production conditions. In this paper we report the production and large-scale purification of the Bm95 protein, following a simple and cost-effective process. The antigen was obtained highly aggregated, forming particles ranging from 26 to 30nm and with purity higher than 80%. The process yield was 0.55 g of pure Bm95 protein per liter of culture. The 98% of the primary structure of the recombinant protein was verified by mass spectrometry. Three amino acid changes in comparison with the sequence deduced from cDNAwere detected by LC-MS=MS. The antigen was also obtained N-glycosylated, as previously reported for heterologous protein expression in P. pastoris. [ABSTRACT FROM AUTHOR]