Major species-specific antibody epitopes of the Ehrlichia chaffeensis p120 and E. canis p140 orthologs in surface-exposed tandem repeat regions.
Ehrlichia chaffeensis and E. canis have a small subset of tandem repeat (TR)-containing protein orthologs, including p120/p140, which elicit strong antibody responses. The TR regions of these protein orthologs are immunoreactive, but the molecular characteristics of the p120/p140 epitopes have not been determined. In this study, the immunodeterminants of the E. chaffeensis p120 and E. canis p140 were identified and molecularly defined. Major antibody epitope-containing regions of both p120 and p140 were localized to the TR regions, which reacted strongly by Western immunoblotting with antibodies in sera from E. chaffeensis-infected dogs or patients and E. canis-infected dogs, respectively. Single continuous species-specific major epitopes within the E. chaffeensis p120 and E. canis p140 TRs were mapped to homologous surface-exposed glutamate/aspartate-rich regions (19 to 22 amino acids). In addition, minor cross-reactive epitopes were localized to homologous N- and C-terminal regions of p120 and p140. Furthermore, although the native and recombinant p120 and p140 proteins exhibited higher-than-predicted molecular masses, posttranslational modifications were not present on abnormally migrating p120 and p140 TR recombinant proteins as determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry.
Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
Tian
T
Luo
Xiaofeng
X
Zhang
Jere W
JW
McBride
D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D003429:Cross Reactions; D004283:Dog Diseases / Q000276:immunology; D004285:Dogs; D041061:Ehrlichia canis / Q000276:immunology*; D018469:Ehrlichia chaffeensis / Q000276:immunology*; D016873:Ehrlichiosis / Q000276:immunology* / Q000662:veterinary; D018604:Epitope Mapping; D018985:Epitopes, B-Lymphocyte; D006801:Humans; D008969:Molecular Sequence Data; D020449:Repetitive Sequences, Amino Acid / Q000276:immunology; D016415:Sequence Alignment
C104346:120-kDa immunodominant protein, Ehrlichia chaffeensis; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D018985:Epitopes, B-Lymphocyte