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United States Department of Agriculture

Agricultural Research Service

Research Project: MINING THE GENOME OF RHIPICEPHALUS MICROPLUS TO DEVELOP NOVEL CONTROL TECHNOLOGY AND VACCINES

Location: Tick and Biting Fly Research

Title: Protective Immunity Against Tick Infestation in Cattle Vaccinated with Recombinant Trypsin Inhibitor of Rhipicephalus Microplus

Authors
item Andreotti, Renato -
item Casquero Cunha, Rodrigo -
item Aparecida Soares, Mariana -
item Guerrero, Felix
item Leivas Leite, Fabio -
item Perez De Leon, Adalberto

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 28, 2012
Publication Date: September 7, 2012
Citation: Andreotti, R., Casquero Cunha, R., Aparecida Soares, M., Guerrero, F., Leivas Leite, F.P., Perez De Leon, A.A. 2012. Protective immunity against tick infestation in cattle vaccinated with recombinant trypsin inhibitor of Rhipicephalus microplus. Vaccine. 30:6678-6685.

Interpretive Summary: The southern cattle fever tick, Rhipicephalus microplus, and the related cattle fever tick species, R. annulatus, collectively referred to herein as Cattle Fever Ticks (CFT), transmit the microbes that cause bovine babesiosis and anaplasmosis. Direct effects of CFT on animal health are associated with their obligate blood feeding habit. Coordinated efforts by the Cattle Fever Tick Eradication Program that began in 1907 resulted in the eradication of CFT from the United States in 1943. A permanent quarantine zone is maintained in south Texas along the border with Mexico to buffer tick incursions from this neighboring country where CFT are established. Livestock production is impacted wherever CFT are present and R. microplus is regarded as the most economically important external parasite of cattle in the world. Synthetic chemicals have been widely used to try to control CFT. A drawback with this approach now is the inability of the chemicals used to kill certain CFT populations. This problem is caused by the indiscriminate use of chemicals designed to kill ticks, also known as acaricides. This practice selects for resistance among CFT populations. Vaccination against R. microplus infestation is another technology that can be integrated for effective cattle tick control and potentially eradication, provided a highly efficacious vaccine against that tick species becomes commercially available. Certain proteins present in CFT belong to a group described as the Kunitz-bovine pancreatic trypsin inhibitor family. Members of this protein family are abundant in CFT salivary glands, midgut, and ovaries. These organs are attractive targets for the development of a novel R. microplus vaccine. Efficacy assessment against tick infestation in bovines using a vaccine containing the recombinant form of a member of the Kunitz family from R. microplus produced in a yeast expression system is reported for the first time here. The yeast was bioengineered to produce the recombinant version of a trypsin inhibitor that is expressed in R. microplus larvae (rRmLTI). Immunization with rRmLTI afforded 32% efficacy against R. microplus. Bioinformatics analysis of the partial nucleotide and deduced amino acid sequences indicated that rRmLTI closely resembles BmTI-6, which is a three-headed Kunitz protein present in the ovary and fat tissues of R. microplus.

Technical Abstract: The southern cattle fever tick, Rhipicephalus microplus, and the related cattle fever tick species, R. annulatus, collectively referred to herein as Cattle Fever Ticks (CFT), transmit Babesia bovis and B. bigemina, and Anaplasma marginale, that cause bovine babesiosis and anaplasmosis, respectively. Direct effects of CFT on animal health are associated with their obligate blood feeding habit. Coordinated efforts by the Cattle Fever Tick Eradication Program that began in 1907 resulted in the eradication of CFT from the United States in 1943. A permanent quarantine zone is maintained in south Texas along the border with Mexico to buffer tick incursions from this neighboring country where CFT are established. Livestock production is impacted wherever CFT are present and R. microplus is regarded as the most economically important external parasite of cattle in the world. Synthetic chemicals have been widely used to try to control CFT. A drawback with this approach now is the inability of the chemicals used to kill certain CFT populations. The problem is caused by the indiscriminate use of chemicals designed to kill ticks, also known as acaricides. This practice selects for resistance among CFT populations. Vaccination against R. microplus infestation is another technology that can be integrated for effective cattle tick control and potentially eradication, provided a highly efficacious vaccine against that tick species becomes commercially available. Certain proteins present in CFT belong to a group described as the Kunitz-bovine pancreatic trypsin inhibitor family. Members of this protein family are abundant in CFT salivary glands, midgut, and ovaries. These organs are attractive targets for the development of a novel R. microplus vaccine. Efficacy assessment against tick infestation in bovines using a vaccine containing the recombinant form of a member of the Kunitz family from R. microplus produced in a yeast expression system is reported for the first time here. The yeast Pichia pastoris was bioengineered to produce the recombinant version of a trypsin inhibitor that is expressed in R. microplus larvae (rRmLTI). Immunization with rRmLTI afforded 32% efficacy against R. microplus. The estimated molecular weight of rRmLTI was 46 kDa. Structural homology to the native form of the larval trypsin inhibitor was documented by recognition of rRmLTI in Western-blots using polyclonal antibodies from mice immunized with cattle tick larval extract or rRmLTI. Bioinformatics analysis of the partial nucleotide and deduced amino acid sequences indicated that rRmLTI closely resembles BmTI-6, which is a three-headed Kunitz protein present in the ovary and fat tissues of R. microplus.

Last Modified: 11/28/2014
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