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Babesia bovis rhoptry-associated protein 1 is immunodominant for T helper cells of immune cattle and contains T-cell epitopes conserved among geographically distant B. bovis strains.
Title | Babesia bovis rhoptry-associated protein 1 is immunodominant for T helper cells of immune cattle and contains T-cell epitopes conserved among geographically distant B. bovis strains. |
Publication Type | Journal Article |
Year of Publication | 1996 |
Authors | Brown, WC, McElwain, TF, Ruef, BJ, Suarez, CE, Shkap, V, Chitko-McKown, CG, Tuo, W, Rice-Ficht, AC, Palmer, GH |
Journal | Infect Immun |
Volume | 64 |
Issue | 8 |
Pagination | 3341-50 |
Date Published | 1996 Aug |
ISSN | 0019-9567 |
Keywords | Animals, Antigens, Protozoan, Babesia bovis, Babesiosis, Base Sequence, Cattle, Cattle Diseases, Clone Cells, Conserved Sequence, Cytokines, Epitopes, Erythrocytes, Immunity, Immunodominant Epitopes, Lymphocyte Activation, Molecular Sequence Data, Protozoan Proteins, Recombinant Proteins, T-Lymphocytes, Helper-Inducer |
Abstract | The ability of rhoptry-associated protein 1 (RAP-1) of Babesia bovis and Babesia bigemina to confer partial protective immunity in cattle has stimulated interest in characterizing both B-cell and T-cell epitopes of these proteins. It was previously shown that B. bovis RAP-1 associates with the merozoite surface as well as rhoptries and expresses B-cell epitopes conserved among otherwise antigenically different B. bovis strains. An amino-terminal 307-amino-acid domain of the molecule that is highly conserved in the B. bigemina RAP-1 homolog did not contain cross-reactive B-cell epitopes. The studies reported here demonstrate that B. bovis RAP-1 is strongly immunogenic for T helper (Th) cells from B. bovis-immune cattle and that like B-cell epitopes, Th-cell epitopes are conserved in different B. bovis strains but not in B. bigemina RAP-1. Lymphocytes from cattle immune to challenge with the Mexico strain of B. bovis proliferated against recombinant B. bovis RAP-1 protein derived from the Mexico strain. T-cell lines established by stimulating lymphocytes with recombinant RAP-1 protein responded against B. bovis, but not B. bigemina, merozoites. T-cell lines established by repeated stimulation of lymphocytes with B. bovis membrane antigen proliferated strongly against RAP-1, demonstrating the immunodominant nature of this protein. RAP-1-specific CD4+ T cell clones recognized Mexico, Texas, Australia, and Israel strains of B. bovis but neither B. bigemina merozoites nor recombinant B. bigemina RAP- 1. Analysis of cytokine mRNA in RAP-1-specific Th cell clones revealed strong expression of gamma interferon but little or no expression of interleukin-2 (IL-2), IL-4, or IL-10. Gamma interferon production was confirmed by enzyme-linked imunosorbent assay. These results indicate the potential to use selected B. bovis RAP-1 peptides as immunogens to prime for strong, anamnestic, strain-cross-reactive type 1 immune responses upon exposure to B. bovis. |
Alternate Journal | Infect. Immun. |
PubMed ID | 8757873 |
PubMed Central ID | PMC174227 |
Grant List | AI30136 / AI / NIAID NIH HHS / United States |