This Article Full Text Full Text (PDF) Other Versions of this Article: CVI.00361-06v1 14/2/123    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 Google Scholar Google Scholar Articles by Cárdenas, A. M. Articles by McBride, J. W. Search for Related Content PubMed PubMed Citation Articles by Cárdenas, A. M. Articles by McBride, J. W.

 Previous Article  |  Next Article 

Clinical and Vaccine Immunology, February 2007, p. 123-128, Vol. 14, No. 2
1071-412X/07/$08.00+0     doi:10.1128/CVI.00361-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Enzyme-Linked Immunosorbent Assay with Conserved Immunoreactive Glycoproteins gp36 and gp19 Has Enhanced Sensitivity and Provides Species-Specific Immunodiagnosis of Ehrlichia canis Infection

Department of Pathology,¹ Microbiology and Immunology,² Sealy Center for Vaccine Development,³ the Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas 77555,⁴ Department of Veterinary Pathobiological Sciences, School of Veterinary Medicine,⁵ Department of Veterinary Science, Louisiana State University, Baton Rouge, Louisiana 70803⁶

Received 4 October 2006/ Returned for modification 17 November 2006/ Accepted 27 November 2006

Ehrlichia canis is the primary etiologic agent of canine monocytic ehrlichiosis, a globally distributed and potentially fatal disease of dogs. We previously reported on the identification of two conserved major immunoreactive antigens, gp36 and gp19, which are the first proteins to elicit an E. canis-specific antibody response, and gp200 and p28, which elicit strong antibody responses later in the acute phase of the infection. In this report, the sensitivities and specificities of five recombinant E. canis proteins for the immunodiagnosis of E. canis infection by an enzyme-linked immunosorbent assay (ELISA) were evaluated. Recombinant polypeptides gp36, gp19, and gp200 (N and C termini) exhibited 100% sensitivity and specificity for immunodiagnosis by the recombinant glycoprotein ELISA compared with the results obtained by an indirect fluorescent-antibody assay (IFA) for the detection of antibodies in dogs that were naturally infected with E. canis. Moreover, the enhanced sensitivities of gp36 and gp19 for immunodiagnosis by the recombinant glycoprotein ELISA compared to those obtained by IFA were demonstrated with dogs experimentally infected with E. canis, in which antibodies were detected as much as 2 weeks earlier, on day 14 postinoculation. gp36 and gp19 were not cross-reactive with antibodies in sera from E. chaffeensis-infected dogs and thus provided species-specific serologic discrimination between E. canis and E. chaffeensis infections. This is the first demonstration of the improved detection capability of the recombinant protein technology compared to the capability of the "gold standard" IFA and may eliminate the remaining obstacles associated with the immunodiagnosis of E. canis infections, including species-specific identification and the lack of sensitivity associated with low antibody titers early in the acute phase of the infection.

Published ahead of print on 6 December 2006.