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Title: Knockdown of the rhipicephalus microplus cytochrome c oxidase subunit III gene is associated with a failure of anaplasma marginale transmission

item BIFANO, THAIS - Universidad De Sao Paulo
item Ueti, Massaro
item ESTEVES, ELIANE - Universidad De Sao Paulo
item REIF, KATHRYN - Washington State University
item BRAZ, GLORIA - Universidade Federal Do Rio De Janeiro
item Scoles, Glen
item BASTOS, REGINALDO - Washington State University
item White, Stephen
item DAFFRE, SIRLEI - Universidad De Sao Paulo

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2014
Publication Date: 6/6/2014
Citation: Bifano, T.D., Ueti, M.W., Esteves, E., Reif, K.E., Braz, G.R., Scoles, G.A., Bastos, R.G., White, S.N., Daffre, S. 2014. Knockdown of the rhipicephalus microplus cytochrome c oxidase subunit III gene is associated with a failure of anaplasma marginale transmission. PLoS One. DOI:10.1371/journal.pone.0098614.

Interpretive Summary: Anaplasma marginale is a parasite that infects blood cells of cattle. It is an economically significant impediment to the U. S. cattle industry, both in terms of export restrictions and losses due to disease. This parasite is transmitted by ticks and the ability to understand dynamics of tick transmission is necessary for development of novel control methods. This work demonstrated that suppressing a particular tick gene prevented transmission of A. marginale.

Technical Abstract: Rhipicephalus microplus is an obligate hematophagous ectoparasite of cattle and an important biological vector of Anaplasma marginale in tropical and subtropical regions. The primary determinants for Anaplasma transmission are infection of tick gut epithelial cells followed by infection of salivary glands. Transmission of A. marginale to cattle occurs via saliva during tick feeding. Interference in colonization of either the tick gut or salivary glands can affect transmission of A. marginale to naïve animals. In this study, we used the tick embryonic cell line BME26 to identify tick genes modulated in response to A. marginale infection. Suppression-subtractive hybridization libraries (SSH) were constructed and five up-regulated genes {glutathione S-transferase (GST), cytochrome c oxidase sub III (COXIII), dynein (DYN), synaptobrevin (SYN) and phosphatidylinositol-3,4,5-triphosphate 3-phosphatase (PHOS)} were selected as targets for functional in vivo genomic analysis. RNA interference (RNAi) was used to determine the effect of the knock-down of tick genes on A. marginale infection. Although RNAi consistently knocked-down all individually examined tick genes within infected tick guts and/or salivary glands, ticks injected with dsCOXIII was the sole group that failed to transmit A. marginale to naïve calves. To our knowledge, this is the first report demonstrating that knocking a tick gene down using dsRNA can block A. marginale transmission.