title: Expression of Anaplasma marginale major surface protein 2 operon-associated proteins during mammalian and arthropod infection.
abstract: The antigenically variant major surface protein 2 (MSP2) of Anaplasma marginale is expressed from a 3.5-kb operon that contains, in a 5'-to-3' direction, four open reading frames, opag3, opag2, opag1, and msp2. This operon structure was shown to be conserved among genotypically and phenotypically distinct A. marginale, A. ovis, and A. centrale strains. The individual OpAG amino acid sequences are highly conserved among A. marginale strains, with identities ranging from 95 to 99%. OpAG2 and OpAG3 were expressed by all examined A. marginale strains during the acute rickettsemia in the mammalian host and, like MSP2, localize to the bacterial surface. OpAG2 and OpAG3 were also expressed in an infected Ixodes scapularis tick cell line. In contrast, the same A. marginale strains expressed only OpAG2 in two different Dermacentor spp. during transmission feeding. OpAG1 expression was not detected in the infected mammalian host, the infected tick cell line, or within infected Dermacentor ticks. The differential expression of outer membrane proteins from within an operon is a novel finding in tick-transmitted bacteria, and the regulation of expression may be broadly applicable to understanding how the pathogen adapts to the mammalian host-tick vector transition.
authors.affiliation: Program in Vector-Borne Diseases, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164-7040, USA.
authors.forename: Christiane V
authors.initials: CV
authors.lastname: Löhr
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Brayton
authors.forename: Varda
authors.initials: V
authors.lastname: Shkap
authors.forename: Thea
authors.initials: T
authors.lastname: Molad
authors.forename: Anthony F
authors.initials: AF
authors.lastname: Barbet
authors.forename: Wendy C
authors.initials: WC
authors.lastname: Brown
authors.forename: Guy H
authors.initials: GH
authors.lastname: Palmer
mesh_terms: D000595:Amino Acid Sequence; D000709:Anaplasma / Q000235:genetics*; D000712:Anaplasmosis / Q000378:metabolism*; D000818:Animals; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D002478:Cells, Cultured; D017124:Conserved Sequence; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009876:Operon; D013987:Ticks / Q000382:microbiology*
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; C103348:msp2 protein, Anaplasma marginale