Vaccination against Rhipicephalusmicroplus: an alternative to chemical control? / Potenciais vacinas contra Rhipicephalus microplus: uma alternativa ao controle químico?

Rhipicephalus (Boophilus) microplus is a hard tick endemic in livestock-growing regions and causes economic losses in the largest beef-producing countries, including Brazil, Mexico, Argentina, Australia and Uruguay. The use of chemical acaricides is still the main strategy to control R. microplusinfestations. Nevertheless, immunological control of R. microplus with an anti-tick vaccine is a suitable alternative and has manifold advantages because it can avoid drug-resistance and the presence of acaricide residues in milk, beef and in the environment. Indeed, vaccines based on the Bm86 antigen have had relative commercial and technical success to control R. microplus in some regions. Although, the efficacy of such vaccines varies among tick populations and is insufficient to provide an acceptable level of protection. Therefore, the need to search for better antigens is impelling. This review focused on the restrictions imposed on the use of acaricides in Brazil and in the European Union, as well as on the impacts of Bm86-based vaccines on R. microplus control. The efficacy of experimental anti-tick vaccines (based on subolesin, glutathione S-transferase, ferritin 2; voltage-dependent anion channel; aquaporin, 60 S acidic ribosomal protein, metalloprotease and trypsin) that can elicit an immune response against the physiological functions of various ticks is discussed.

O Rhipicephalus (Boophilus) microplus é um carrapato duro que é endêmico de regiões de pecuária e causa perdas econômicas nos maiores países produtores de carne bovina, incluindo Brasil, México, Argentina, Austrália e Uruguai. O uso de acaricidas ainda é a principal estratégia para controlar infestações por R. microplus. No entanto, o controle imunológico do R. microplus com uma vacina contra carrapatos é uma alternativa adequada e possui diversas vantagens, por evitar a seleção de populações de carrapato resistentes a drogas, evitar a presença de resíduos de acaricidas no leite, na carne e no ambiente. As vacinas baseadas no antígeno Bm86 tiveram relativo sucesso comercial e técnico no controle do R. microplus em diversas regiões. No entanto, a eficácia dessas vacinas varia entre as populações de carrapatos e é insuficiente para fornecer um nível aceitável de proteção. Portanto, há uma necessidade de procurar novos antígenos. Esta revisão foca nas restrições impostas ao uso de acaricidas no Brasil e na União Europeia, bem como nos impactos das vacinas baseadas em Bm86 no controle do R. microplus. Também é discutida a eficácia de vacinas anti-carrapatos experimentais (baseadas em subolesina, glutationa S-transferase, ferritina 2; canal aniônico dependente de voltagem; aquaporina, proteína ribossômica ácida 60S, metaloprotease, tripsina) que podem elicitar uma resposta imune contra as funções fisiológicas de vários carrapatos.

Production of Proteolytic Enzymes by a Keratin-Degrading Aspergillus niger.

A fungal isolate with capability to grow in keratinous substrate as only source of carbon and nitrogen was identified as Aspergillus niger using the sequencing of the ITS region of the rDNA. This strain produced a slightly acid keratinase and an acid protease during cultivation in feather meal. The peak of keratinolytic activity occurred in 48 h and the maximum proteolytic activity in 96 h. These enzymes were partly characterized as serine protease and aspartic protease, respectively. The effects of feather meal concentration and initial pH on enzyme production were evaluated using a central composite design combined with response surface methodology. The optimal conditions were determined as pH 5.0 for protease and 7.8 for keratinase and 20 g/L of feather meal, showing that both models were predictive. Production of keratinases by A. niger is a less-exploited field that might represent a novel and promising biotechnological application for this microorganism.