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United States Department of Agriculture

Agricultural Research Service

Title: Efficient Use of a Small Genome to Generate Antigenic Diversity in Tick-Borne Ehrlichial Pathogens

Authors
item Brayton, K. - WASHINGTON STATE UNIV
item KNOWLES, DONALD
item Mcguire, T. - WASHINGTON STATE UNIV
item Palmer, G. - WASHINGTON STATE UNIV

Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 5, 2001
Publication Date: N/A

Interpretive Summary: These data show that Anaplasma marginale is able to generate antigenic diversity by using partial divergent gene copies, distributed through out the genome as cassettes into a single expression site. Previous data has shown that subunit vaccines, using various combinations of surface proteins provide only partial protection against heterologous challenge. A probable partial explanation for this finding is the ability of A. marginale to change its antigenic character.

Technical Abstract: Ehrlichiae are responsible for important tick-transmitted diseases including anaplasmosis, the most prevalent tick-borne infection of livestock worldwide, and the emerging human disuse monocytic and granulocytic ehrlichiosis. Antigenic variation of major surface proteins is a key feature of these pathogens that allows persistence in the mammalian host, a requisite for subsequent tick transmission. In Anaplasma marginale psuedogens for two antigenically variable gene families, msp2 and msp3 appear in concert. These pseudogenes can be recombined into the functional expression site to generate new antigenic variants. Coordinated control of the recombination of these genes would allow these two gene families to act synergistically to evade the host immune response.

Last Modified: 9/29/2014