ARS | Publication request: Bovine immunoprotection against Rhipicephalus microplus with recombinant Bm86-Campo Grande antigen

Submitted to: Revista Brasileira de Parasitologia Veterinaria
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 14, 2012
Publication Date: N/A

Interpretive Summary: The southern cattle fever tick, Rhipicephalus microplus, is considered to be the most economically important external parasite of cattle globally. It is difficult to control populations of R. microplus that have become resistant to readily available chemical acaricides, which have been used inappropriately. Anti-tick vaccines represent a technology that can be combined with chemical acaricides in integrated control programs to mitigate the economic impact of R. microplus on livestock production systems. The recombinant form of the tick gut protein Bm86 from the Campo Grande (CG) strain of R. microplus was produced using a yeast expression system to test its ability to elicit a protective immune response in cattle against tick infestation. Purification of the antigen rBm86-CG was simplified through the bioprocess followed in these experiments. A specific antibody response in vaccinated cattle detected by enzyme-linked, immunosorbent assay confirmed that rBm86-CG stimulated the immune system of cattle. The rBm86-CG and native form of the protein had a similar shape as documented by the ability of antibodies from vaccinated cattle to recognize a protein in extracts of immature ticks with a molecular weight corresponding to Bm86. The rBm86-CG antigen showed 39% efficacy against the R. microplus CG strain infesting vaccinated cattle in a pen trial. The rBm86-CG is an antigen that could be used in a multi-antigen vaccine as part of an integrated program for the control of R. microplus in the region of Brazil that includes Mato Grosso do Sul.

Technical Abstract: The southern cattle fever tick, Rhipicephalus microplus, is arguably the most economically important external parasite of cattle globally. The inappropriate use of readily available chemical acaricides has driven the evolution of resistance in populations of R. microplus. Anti-tick vaccines represent a technology that can be combined with chemical acaricides in integrated control programs to mitigate the economic impact of R. microplus on livestock production systems. The recombinant form of Bm86 from the Campo Grande (CG) strain of R. microplus was produced using the P. pastoris expression system to test its ability to immunoprotect cattle against tick infestation. Secretion of rBm86-CG in P. pastoris through the bioprocess reported here simplified purification of the antigen. The specific humoral immune response in vaccinated cattle detected by ELISA confirmed the immunogenicity of rBm86-CG. Immunoblot results revealed that polyclonal antibodies from vaccinated cattle recognized a protein in larval extracts with a molecular weight corresponding to Bm86, which indicated conformational resemblance between rBm86-CG and the native protein form. The rBm86-CG antigen showed 39% efficacy against the Campo Grande strain of R. microplus infesting vaccinated cattle in a pen trial. The rBm86-CG is an antigen that could be used in a polyvalent vaccine as part of an integrated program for the control of R. microplus in the region that includes Mato Grosso do Sul.