title: Complete genome sequencing of Anaplasma marginale reveals that the surface is skewed to two superfamilies of outer membrane proteins.
abstract: The rickettsia Anaplasma marginale is the most prevalent tick-borne livestock pathogen worldwide and is a severe constraint to animal health. A. marginale establishes lifelong persistence in infected ruminants and these animals serve as a reservoir for ticks to acquire and transmit the pathogen. Within the mammalian host, A. marginale generates antigenic variants by changing a surface coat composed of numerous proteins. By sequencing and annotating the complete 1,197,687-bp 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 that 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.
authors.affiliation: Program in Vector-Borne Diseases, Department of Veterinary Microbiology and Pathology, Washingston State University, Pullman, WA 99164-7040, USA. kbrayton@vetmed.wsu.edu
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Brayton
authors.forename: Lowell S
authors.initials: LS
authors.lastname: Kappmeyer
authors.forename: David R
authors.initials: DR
authors.lastname: Herndon
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Dark
authors.forename: David L
authors.initials: DL
authors.lastname: Tibbals
authors.forename: Guy H
authors.initials: GH
authors.lastname: Palmer
authors.forename: Travis C
authors.initials: TC
authors.lastname: McGuire
authors.forename: Donald P
authors.initials: DP
authors.lastname: Knowles
mesh_terms: D042322:Anaplasma marginale / Q000235:genetics*; D000940:Antigenic Variation; D000942:Antigens, Bacterial / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001483:Base Sequence; D016056:Immunodominant Epitopes; D008969:Molecular Sequence Data; D005810:Multigene Family; D011544:Pseudogenes; D017421:Sequence Analysis
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D016056:Immunodominant Epitopes; C449089:major surface protein 1a, Anaplasma; C450434:major surface protein 1b, Anaplasma; C103348:msp2 protein, Anaplasma marginale