This Article Full Text Full Text (PDF) Other Versions of this Article: IAI.01494-06v1 75/1/74    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by McBride, J. W. Articles by Woods, M. E. Search for Related Content PubMed PubMed Citation Articles by McBride, J. W. Articles by Woods, M. E.

 Previous Article  |  Next Article 

Infection and Immunity, January 2007, p. 74-82, Vol. 75, No. 1
0019-9567/07/$08.00+0     doi:10.1128/IAI.01494-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Identification of a Glycosylated Ehrlichia canis 19-Kilodalton Major Immunoreactive Protein with a Species-Specific Serine-Rich Glycopeptide Epitope

Departments of Pathology,¹ Microbiology and Immunology,² Center for Biodefense and Emerging Infectious Diseases,³ Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas 77555⁴

Received 18 September 2006/ Returned for modification 12 October 2006/ Accepted 24 October 2006

Ehrlichia canis has a small subset of major immunoreactive proteins that includes a 19-kDa protein that elicits an early Ehrlichia-specific antibody response in infected dogs. We report herein the identification and molecular characterization of this highly conserved 19-kDa major immunoreactive glycoprotein (gp19) ortholog of the Ehrlichia chaffeensis variable-length PCR target (VLPT) protein. E. canis gp19 has substantial carboxyl-terminal amino acid homology (59%) with E. chaffeensis VLPT and the same chromosomal location; however, the E. chaffeensis VLPT gene (594 bp) has tandem repeats that are not present in the E. canis gp19 gene (414 bp). Consistent with other ehrlichial glycoproteins, the gp19 protein exhibited a larger-than-predicted mass (3 kDa), O-linked glycosylation sites were predicted in an amino-terminal serine/threonine/glutamate (STE)-rich patch (26 amino acids), carbohydrate was detected on the recombinant gp19 protein, and the neutral sugars glucose and galactose were detected on the recombinant amino-terminal polypeptide. E. canis gp19 composition consists of five predominant amino acids, cysteine, glutamate, tyrosine, serine, and threonine, concentrated in the STE-rich patch and a carboxyl-terminal domain predominated by cysteine and tyrosine (55%). The amino-terminal STE-rich patch contained a major species-specific antibody epitope strongly recognized by serum from an E. canis-infected dog. The recombinant glycopeptide epitope was substantially more reactive with antibody than the synthetic (nonglycosylated) peptide, and periodate treatment of the recombinant glycopeptide epitope reduced its immunoreactivity, demonstrating the importance of a carbohydrate immunodeterminant(s). The gp19 protein was present on reticulate and dense-cored cells, and it was found extracellularly in the fibrillar matrix and associated with the morula membrane, the host cell cytoplasm, and the nucleus.

Published ahead of print on 6 November 2006.

Editor: W. A. Petri, Jr.

This article has been cited by other articles:

• Sarkar, M., Troese, M. J., Kearns, S. A., Yang, T., Reneer, D. V., Carlyon, J. A. (2008). Anaplasma phagocytophilum MSP2(P44)-18 Predominates and Is Modified into Multiple Isoforms in Human Myeloid Cells. Infect. Immun. 76: 2090-2098 [Abstract] [Full Text]  
• Nethery, K. A., Doyle, C. K., Zhang, X., McBride, J. W. (2007). Ehrlichia canis gp200 Contains Dominant Species-Specific Antibody Epitopes in Terminal Acidic Domains. Infect. Immun. 75: 4900-4908 [Abstract] [Full Text]  
• Cardenas, A. M., Doyle, C. K., Zhang, X., Nethery, K., Corstvet, R. E., Walker, D. H., McBride, J. W. (2007). Enzyme-Linked Immunosorbent Assay with Conserved Immunoreactive Glycoproteins gp36 and gp19 Has Enhanced Sensitivity and Provides Species-Specific Immunodiagnosis of Ehrlichia canis Infection. CVI 14: 123-128 [Abstract] [Full Text]