Bovine immunoprotection against Rhipicephalus (Boophilus) microplus with recombinant Bm86-Campo Grande antigen

Abstract

The southern cattle fever tick, Rhipicephalus (Boophilus) microplus, is no doubt the most economically important ectoparasite of cattle globally. The inappropriate use of chemical acaricides has driven the evolution of resistance in populations of R. (B.) microplus. Anti-tick vaccines represent a technology that can be combined with acaricides in integrated control programs to mitigate the impact of R. (B.) microplus. The recombinant form of Bm86 antigen from the Campo Grande (rBm86-CG) strain of R. (B.) microplus was produced using the Pichia pastoris expression system to test its ability to immunoprotect cattle against tick infestation. Secretion of rBm86-CG by P. pastoris through the bioprocess reported here simplified purification of the antigen. A specific humoral immune response was detected by ELISA in vaccinated cattle. Immunoblot results revealed that polyclonal antibodies from vaccinated cattle recognized a protein in larval extracts with a molecular weight corresponding to Bm86. The rBm86-CG antigen showed 31% efficacy against the Campo Grande strain of R. (B.) microplus infesting vaccinated cattle. 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. (B.) microplus in the region that includes Mato Grosso do Sul.Keywords: Tick, Rhipicephalus (Boophilus) microplus, anti-tick vaccine, recombinant Bm86, Pichia pastoris. ResumoO carrapato Rhipicephalus (Boophilus) microplus é, sem dúvidas, o ectoparasito economicamente mais importante para o gado a nível mundial. A utilização inadequada de acaricidas tem impulsionado a evolução da resistência em populações de R. (B.) microplus. Vacinas contra o carrapato representam uma tecnologia que pode ser combinada com acaricidas em programas de controle integrado para diminuir o impacto de R. (B.) microplus. A forma recombinante da Bm86 da cepa Campo Grande (rBm86-CG) de R. (B.) microplus foi produzido utilizando o sistema de expressão em Pichia pastoris para testar sua capacidade de imunoproteção ao gado contra a infestação de carrapatos. A secreção de rBm86-CG em P. pastoris pelo bioprocesso, simplificou a purificação do antígeno. A resposta imune humoral específica foi detectada por ELISA em soros de bovinos vacinados. Resultados de "imunoblot" revelaram que anticorpos policlonais de bovinos vacinados reconheceram uma proteína em extratos de larvas com um peso molecular correspondente à Bm86. O antígeno rBm86-CG mostrou eficácia de 31% contra a amostra CG de R. (B.) microplus utilizada para infestar os bovinos vacinados. Pelos resultados obtidos, concluímos que a rBm86-CG é um antígeno que pode ser usado em uma vacina polivalente, como parte de um programa integrado para o controle de R. (B.) microplus no estado do Mato Grosso do Sul, Brasil.

Calculation of the efficacy of vaccines against tick infestations on cattle

“…Intramuscular injection was most commonly used (16/25), followed by subcutaneous injection (7/25). Two studies did not report the vaccine inoculation route (ANDREOTTI et al, 2012;CANALES et al, 1997).…”

“…The first 3 articles on cattle tick vaccines were published in this journal (CANALES et al, 1997;FRAGOSO et al, 1998;GARCÍA-GARCÍA et al, 2000). Years later, another 6 articles were published (ANDREOTTI et al, 2012;DE LA FUENTE et al, 2010;GALAÏ et al, 2012;HAJDUSEK et al, 2010;MERINO et al, 2011;MILLER et al, 2012). Notably, all studies were published in high impact journals in the fields of veterinary medicine, parasitology and animal health.…”

“…For Bm86, there is a direct correlation between the titer of antibodies to this antigen and the efficacy of vaccination, measured through the direct effect on the fertility of the ticks engorged on vaccinated grazing cattle (DE LA FUENTE et al, 1998). There is also a correlation between antibody titers to others antigens, such as Bm95, Subolisin (SUB), Elongation Factor 1a (EF1a), Ubiquitin (UBQ), akirin (AKR) and Trypsin Inhibitor (RmLTI), and the vaccine efficacy ANDREOTTI et al, 2012;CARREÓN et al, 2012;DE LA FUENTE et al, 1998;HAVLÍKOVÁ et al, 2013;MERINO et al, 2011;MORENO-CID et al, 2013). In some experiments, different Bm86 amounts were tested, and 100 µg was accepted as the optimal composition RODRÍGUEZ et al, 1994;WILLADSEN et al, 1989).…”

“…The latter formula fails to consider whether the eggs are fertile and may underestimate the vaccine efficacy. For example, the vaccinated group may have a normal production of eggs or even slightly above the control group, although these eggs are not as fertile as those in the control group (ANDREOTTI et al, 2012;CUNHA et al, 2012). Therefore, the most complete formula for calculating the percentage of efficacy includes the three effects and ultimately represents how much the vaccine reduced the infestation, the extent of its effect on the oviposition of ticks that survived and the fertility of the eggs that were laid were compared to the control population.…”

Immunoprotective potential of a Rhipicephalus (Boophilus) microplus metalloprotease

“…The glycoprotein Bm86, a tick gut epithelial cell protein (Rand et al, 1989;Muhammad et al, 2008), became the first tick antigen used in a commercial vaccine (Canales et al, 1997;Willadsen, 2004;de la Fuente et al, 2007). Since this antigen does not confer enough protection against several R. microplus populations (Garcia-Garcia et al, 2000;Cunha et al, 2012), the search for new recombinant proteins for an anti-tick vaccine gained a strong impetus (Willadsen, 2006;Willadsen, 2004;Guerrero et al, 2012). Potential candidate antigens in the composition of a vaccine against R. microplus include proteins with a role in several physiological process regulations (Willadsen et al, 1996;Parizi et al, 2012a;de la Fuente and Merino, 2013).…”