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2011 Annual Report

1a. Objectives (from AD-416)
Our project objective is to study the tick vector-pathogen interface using the experimental system of Boophilus microplus, the southern cattle tick, and Anaplasma marginale, a rickettsial pathogen of cattle which is transmitted by B. microplus. Development of pathogen infectivity in the tick vector is coordinated with tick feeding, thus ensuring an efficient transmission of the pathogen to susceptible livestock. The long term objective is an enhanced understanding of pathogensis in this system leading to development of technologies to block disease transmission. We expect to have identified specific pathways that are regulated at the time when pathogen infectivity develops and transmission occurs.

1b. Approach (from AD-416)
Integrated A. marginale-B. microplus microarrays will be developed using the completed A. marginale genome sequence and the existing B. microplus gene index database of expressed sequence tags. The microarrays will be used to identify networks of pathogen and tick vector gene expression profiles during the development of A. marginale infectivity within B. microplus. Differential gene transcription in the tick will be assayed using midguts and salivary glands of B. microplus, comparing RNA isolated from tissues of ticks reared in conditions under which infectivity develops or fails to develop. Lastly, we will veify the integrated pathogen and tick vector gene expression patterns by proteomic and quantitative PCR analysis.

3. Progress Report
Through this agreement, a laboratory-centered university course at University of Houston-Clear Lake was established and funded, with R. microplus BAC clone sequencing as the primary objective for the students enrolled in the course. Sequence assembly and bioinformatic analysis results are available to ARS, and this will contribute to progress toward project objectives. DNA isolations have been completed for 96 BAC clones and sequencing was accomplished. This project is monitored by frequent emails and phone conferences between the ARS scientist and the cooperator.

4. Accomplishments