|Knowles, Donald - Don|
Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2004
Publication Date: 1/18/2005
Citation: Brayton, K.A., Kappmeyer, L.S., Herndon, D.R., Dark, M.J., Tibbals, D.L., Palmer, G.H., Mcguire, T.C., Knowles Jr, D.P. 2005. Complete genome sequencing of anaplasma marginale reveals that the surface is skewed to two superfamilies of outer membrane proteins. Proceedings of the National Academy of Sciences. 102(3):844-849. Interpretive Summary: This manuscript reports the complete nucleotide sequence and gene predictions of the Saint Maries strain of Anaplasma marginale. This strain was obtained from an outbreak of anaplasmosis within the United States. The complete set of gene predictions, especially those genes predicted to encode proteins on the surface of the organism will be used in vaccine development. Also an understanding of biochemical pathways utilized by Anaplasma marginale will be used to develop new strategies to block transmission to vector ticks.
Technical Abstract: The rickettsia Anaplasma marginale is the most prevalent tick-borne livestock pathogen worldwide and is a severe constraint to animal health and production in tropical countries. Transmission requires infected ruminants as a reservoir for ticks to acquire the pathogen. A. marginale establishes lifelong persistent infection in the reservoir animal, thus providing a continuous source of pathogen for transmission. A. marginale generates antigenic variants by changing a surface coat composed of numerous proteins. By sequencing and annotating the complete 1,197,687 base pair genome of the St. Maries strain of A. marginale, we show that this surface coat is dominated by two families containing immunodominant proteins: the msp2 superfamily and the msp1 superfamily. Of the 949 annotated coding sequences, just 62 are predicted to be outer membrane proteins, and of these, 49 belong to one of these two superfamilies. The genome contains unusual functional pseudogenes which belong to the msp2 superfamily and play an integral role in surface coat antigenic variation, and are thus distinctly different from pseudogenes described as byproducts of reductive evolution in other Rickettsiales.