Composition of the Surface Proteome of Anaplasma marginale and Its Role in Protective Immunity Induced by Outer Membrane Immunization

• Published in: Infection and Immunity Vol. 76; no. 5; pp. 2219 - 2226
• Main Authors: Noh, Susan M, Brayton, Kelly A, Brown, Wendy C, Norimine, Junzo, Munske, Gerhard R, Davitt, Christine M, Palmer, Guy H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01-05-2008; American Society for Microbiology (ASM)
• Subjects: Analytical, structural and metabolic biochemistry; Anaplasma marginale; Anaplasma marginale - chemistry; Anaplasma marginale - immunology; Anaplasmosis - prevention & control; Anemia - prevention & control; Animals; antibody formation; Applied microbiology; Arthropoda; Bacteremia - prevention & control; bacterial antigens; Bacterial Outer Membrane Proteins - analysis; Bacterial Outer Membrane Proteins - immunology; Bacterial Outer Membrane Proteins - isolation & purification; bacterial proteins; Bacterial Vaccines - immunology; Bacteriology; Biological and medical sciences; Cattle; Cell Line; cell membranes; Chromatography, Liquid; Ehrlichia; erythrocytes; Erythrocytes - microbiology; Fundamental and applied biological sciences. Psychology; immunity; immunization; isolation; Ixodidae; Mass Spectrometry; Membrane Proteins - analysis; Membrane Proteins - immunology; Membrane Proteins - isolation & purification; Microbial Immunity and Vaccines; Microbiology; Miscellaneous; outer membrane proteins; protein composition; Proteins; proteome; Proteome - analysis; Proteome - immunology; Proteome - isolation & purification; surface proteome; ticks; Ticks - microbiology; vaccination; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects); Rickettsiales; Immunoprotection; Immunization; Microbiology; Anaplasmataceae; Bacteria; Proteome; Vaccine; Anaplasma marginale; External membrane; Immunity
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/IAI.00008-08

Surface proteins of tick-borne, intracellular bacterial pathogens mediate functions essential for invasion and colonization. Consequently, the surface proteome of these organisms is specifically relevant from two biological perspectives, induction of protective immunity in the mammalian host and understanding the transition from the mammalian host to the tick vector. In this study, the surface proteome of Anaplasma marginale, a tick-transmitted bacterial pathogen, was targeted by using surface-specific cross-linking to form intermolecular bonds between adjacent proteins. Liquid chromatography and tandem mass spectroscopy were then employed to characterize the specific protein composition of the resulting complexes. The surface complexes of A. marginale isolated from erythrocytes of the mammalian host were composed of multiple membrane proteins, most of which belong to a protein family, pfam01617, which is conserved among bacteria in the genus Anaplasma and the closely related genus EHRLICHIA: In contrast, the surface proteome of A. marginale isolated from tick cells was much less complex and contained a novel protein, AM778, not identified within the surface proteome of organisms from the mammalian host. Immunization using the cross-linked surface complex induced protection against high-level bacteremia and anemia upon A. marginale challenge of cattle and effectively recapitulated the protection induced by immunization with whole outer membranes. These results indicate that a surface protein subset of the outer membrane is capable of inducing protective immunity and serves to direct vaccine development. Furthermore, the data support that remodeling of the surface proteome accompanies the transition between mammalian and arthropod hosts and identify novel targets for blocking transmission.