Identification of a T-Cell Epitope That Is Globally Conserved among Outer Membrane Proteins (OMPs) OMP7, OMP8, and OMP9 of Anaplasma marginaleStrains and with OMP7 from the A. marginalesubsp. centraleVaccine Strain

ABSTRACTWithin the protective outer membrane (OM) fraction of Anaplasma marginale, several vaccine candidates have emerged, including a family of OM proteins (OMPs) 7 to 9, which share sequence identity with each other and with the single protein OMP7 in the vaccine strain A. marginalesubsp. centrale.A. marginaleOMPs 7 to 9 are logical vaccine candidates because they are surface exposed, present in the OM immunogen and protective cross-linked OM proteins, recognized by immune serum IgG2 and T cells in cattle immunized with OM, and recognized by immune serum IgG2 from cattle immunized with the A. centralevaccine strain. We report the identification of a globally conserved 9-amino-acid T-cell epitope FLLVDDAI/VV shared between A. centralevaccine strain OMP7 and the related A. marginaleOMPs 7 to 9, where position 8 of the peptide can be isoleucine or valine. The epitope is conserved in American A. marginalestrains, in the Australia Gypsy Plains strain, and in multiple field isolates from Ghana. This epitope, together with additional T-cell epitopes that are present within these proteins, should be considered for inclusion in a multivalent vaccine for A. marginalethat can provide protection against disease caused by globally distributed bacterial strains.