Affiliation:
1. Departments of Pathology
2. Microbiology and Immunology
3. Center for Biodefense and Emerging Infectious Diseases
4. Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas 77555-0609
Abstract
ABSTRACT
Species-specific antibody epitopes within several major immunoreactive protein orthologs of
Ehrlichia
species have recently been identified and molecularly characterized. In this study, dominant B-cell epitopes within the acidic (pI 5.35) ankyrin repeat-containing 200-kDa major immunoreactive protein (gp200) of
Ehrlichia canis
were defined. The
E. canis
gp200 gene (4,263 bp; 1,421 amino acids) was cloned and expressed as four (N-terminal, 1,107 bp; N-internal, 910 bp; C-internal, 1,000 bp; and C-terminal, 1,280 bp) overlapping recombinant proteins. The N-terminal, C-internal, and C-terminal polypeptides (369, 332, and 426 amino acids, respectively) were strongly recognized by antibody, and the major epitope(s) in these polypeptides was mapped to four polypeptide regions (40 to 70 amino acids). Smaller overlapping recombinant polypeptides (14 to 15 amino acids) spanning these regions identified five strongly immunoreactive species-specific epitopes that exhibited conformational dependence. The majority of the epitopes (four) were located in two strongly acidic (pI 4 to 4.9) domains in the distal N- and C-terminal regions of the protein flanking the centralized ankyrin domain-containing region. The amino acid content of the epitope-containing domains included a high proportion of strongly acidic amino acids (glutamate and aspartate), and these domains appear to have important biophysical properties that influence the antibody response to gp200.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
24 articles.
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