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Conformational dependence and conservation of an immunodominant epitope within the babesia equi erythrocyte-stage surface protein equi merozoite antigen 1.
- Source :
-
Clinical and diagnostic laboratory immunology [Clin Diagn Lab Immunol] 2002 Nov; Vol. 9 (6), pp. 1301-6. - Publication Year :
- 2002
-
Abstract
- Equi merozoite antigen 1 (EMA-1) is an immunodominant Babesia equi erythrocyte-stage surface protein. A competitive enzyme-linked immunosorbent assay (ELISA), based on inhibition of monoclonal antibody (MAb) 36/133.97 binding to recombinant EMA-1 by equine anti-B. equi antibodies, detects horses infected with strains present throughout the world. The objectives of this study were to define the epitope bound by MAb 36/133.97 and quantify the amino acid conservation of EMA-1, including the region containing the epitope bound by MAb 36/133.97. The alignment of the deduced amino acid sequence of full-length EMA-1 (Florida isolate) with 15 EMA-1 sequences from geographically distinct isolates showed 82.8 to 99.6% identities (median, 98.5%) and 90.5 to 99.6% similarities (median, 98.9%) between sequences. Full-length and truncated recombinant EMA-1 proteins were expressed and tested for their reactivities with MAb 36/133.97. Binding required the presence of amino acids on both N- and C-terminal regions of a truncated peptide (EMA-1.2) containing amino acids 1 to 98 of EMA-1. This result indicated that the epitope defined by MAb 36/133.97 is dependent on conformation. Sera from persistently infected horses inhibited the binding of MAb 36/133.97 to EMA-1.2 in a competitive ELISA, indicating that equine antibodies which inhibit binding of MAb 36/133.97 also recognize epitopes in the same region (the first 98 residues). Within this region, the deduced amino acid sequences had 85.7 to 100% identities (median, 99.0%), with similarities of 94.9 to 100% (median, 100%). Therefore, the region which binds to both MAb 36/133.97 and inhibiting equine antibodies has a median amino acid identity of 99.0% and a similarity of 100%. These data provide a molecular basis for the use of both EMA-1 and MAb 36/133.97 for the detection of antibodies against B. equi.
- Subjects :
- Amino Acid Sequence
Animals
Antibodies, Monoclonal immunology
Cloning, Molecular
Horses
Membrane Proteins chemistry
Molecular Sequence Data
Protein Conformation
Protozoan Proteins chemistry
Recombinant Proteins immunology
Antigens, Protozoan immunology
Babesia immunology
Erythrocytes parasitology
Immunodominant Epitopes
Membrane Proteins immunology
Protozoan Proteins immunology
Subjects
Details
- Language :
- English
- ISSN :
- 1071-412X
- Volume :
- 9
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Clinical and diagnostic laboratory immunology
- Publication Type :
- Academic Journal
- Accession number :
- 12414764
- Full Text :
- https://doi.org/10.1128/cdli.9.6.1301-1306.2002