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

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Title: Rhipicephalus (Boophilus) microplus aquaporin as an effective vaccine antigen to protect against cattle tick infestations

Author
item Guerrero, Felicito - Felix
item Andreotti, Renato - Embrapa
item Bendele, Kylie
item Cunha, Rodrigo - Embrapa
item Miller, Robert
item Yeater, Kathleen
item Perez De Leon, Adalberto - Beto

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2014
Publication Date: 10/12/2014
Publication URL: http://handle.nal.usda.gov/10113/62124
Citation: Guerrero, F., Andreotti, R., Bendele, K.G., Cunha, R.C., Miller, R., Yeater, K.M., Perez De Leon, A.A. 2014. Rhipicephalus (Boophilus) microplus aquaporin as an effective vaccine antigen to protect against cattle tick infestations. Parasites & Vectors. 7:475.

Interpretive Summary: Aquaporins, originally called water channels, are protein channels that allow the regulation of water transport across cell membranes. Members of the aquaporin family have been found in animal taxa ranging from mammals to bacteria. They are very common in certain cell types, with approximately 150,000 aquaporin channels found in each red blood cell. The structure of the aquaporins is such that two constrictions in the central pore of the protein act as filters whose selectivity for water, glycerol, urea, and other small molecules is determined by the size and charge of the constriction. Because cattle ticks ingest large volumes of blood relative to their body size and weight, they are required to have efficient water transport mechanisms that can concentrate the blood components. Thus, the tick aquaporins are critical to tick physiology and appeared a good protein to target with an anti-cattle tick vaccine. A cDNA encoding an aquaporin from the cattle tick, Rhipicephalus microplus, was isolated from gene studies in the tick and the efficacy of this aquaporin as an antigen against the cattle tick was explored in cattle vaccine trials conducted in Brazil. The experimental vaccine containing the aquaporin protein provided 72% and 68% efficacy in two cattle pen trials conducted in Campo Grande, Brazil, on groups including 6 one-year old Holstein calves, showing that this cattle tick protein holds promise as an antigen in cattle vaccines targeted against infestations by R. microplus.

Technical Abstract: A cDNA encoding an aquaporin from the cattle tick, Rhipicephalus microplus, was isolated from transcriptomic studies. Bioinformatic analysis indicates this aquaporin, designated RmAQP1, shows greatest amino acid similarity to the human aquaporin 7 family. Members of this family of water-conducting channels can also facilitate the transport of glycerol in addition to water. The efficacy of this aquaporin as an antigen against the cattle tick was explored in cattle vaccine trials conducted in Brazil. A cDNA encoding a significant portion of RmAQP1 was expressed as a recombinant protein in Pichia pastoris, purified under native conditions using a polyhistidine C-terminus tag and nickel affinity chromatography, emulsified with Montanide adjuvant, and cattle vaccinated intramuscularly. The recombinant protein provided 72% and 68% efficacy in two cattle pen trials conducted in Campo Grande, Brazil, on groups including 6 one-year old Holstein calves, showing that this cattle tick protein holds promise as an antigen in cattle vaccines targeted against infestations by R. microplus.