The Bm86 Discovery: A Revolution in the Development of Anti-Tick Vaccines

Abstract

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.

Development and field evaluation of PCR assays based on minimum length Bm86 cDNA fragments required for Rhipicephalus and Hyalomma tick species delineation

“…Second, research showed that the phylogeny based on the complete or almost complete sequence of this transcript was in perfect agreement with the recent taxonomy of hard ticks ( 31 , 77 ). This made it an ideal candidate for species identification as it had already demonstrated its utility in representing the genetic diversity of these ticks ( 78 – 81 ). Furthermore, using this transcript as a marker for species identification would help to better understand the evolution and ecology of these ticks, which are important vectors of various diseases affecting livestock and humans.…”

Cross-species immunoprotective antigens (subolesin, ferritin 2 and P0) provide protection against Rhipicephalus sanguineus sensu lato

“…The cattle tick Rhipicephalus microplus -derived midgut protein Bm86 is currently the only commercialized anti-tick vaccine antigen available [ 1 – 3 ], but its anti-tick vaccine efficacy varies against different strains and species of ticks from different parts of the world [ 4 ]. This limitation has led several research groups to test novel antigens for anti-tick vaccine development [ 5 ], but only a few antigens have been found to induce adequate immune protection against multiple tick species [ 6 – 13 ], and some antigens failed to affect the physiological parameters of the tick tested[ 14 – 16 ].…”

Testing Efficacy of a Conserved Polypeptide from the Bm86 Protein against Rhipicephalus microplus in the Mexican Tropics

“…Hence, alternative approaches have been proposed, including pasture rotation, selection of resistant cattle ( Bos indicus ), and biological control using tick-predatory organisms, such as fungi, nematodes, bacteria, and arthropods [ 10 , 11 , 12 , 13 ]; most of these practices are desirable to reduce chemical residues in cattle products and the environment [ 14 ]. On the other hand, immunological control is one of the most important approaches developed since the 1990s and uses the Bm86 antigen, a glycoprotein located at the epithelial cell membrane of the R. microplus tick gut [ 15 , 16 , 17 ]. Commercial tick vaccines have been distributed as TickGARD TM (Australia), GAVAC TM (Latin America), and, more recently, Bovimune Ixovac TM (Mexico).…”

“…These patterns also have been observed in the Bm86 protein in Mexican R. microplus strains [ 23 ]. Nevertheless, field trials with Bm86-derived vaccines have been established in Latin America and Australia as an integrated tick management program; the program controlled R. microplus infestations through reduced tick feeding, decreased reproductive capacity and egg lying, and the reduction of larvae in the field in subsequent generations [ 15 , 24 ].…”