title: Persistence of antibodies against epitopes encoded by a single gene copy of the Babesia bovis merozoite surface antigen 1 (MSA-1).
abstract: The Babesia bovis merozoite surface antigen-1 (MSA-1) is an immunodominant, neutralization-sensitive merozoite surface antigen encoded by a polymorphic gene family. MSA-1 antigenic polymorphism results in a complete lack of immunologic cross-reactivity among strains. It is unknown how rapidly this antigenic shift occurs, or whether it evolves in the mammalian host. To determine whether the dominant epitopes encoded by a single msa-1 gene copy vary during the course of a single infection, the antibody response to these epitopes was measured after infection of cattle with the Mo7 biologically cloned strain of B. bovis using an Mo7 gene copy-specific enzyme-linked immunosorbent assay. Antibodies against MSA-1 encoded by this gene copy were detected by postinoculation (PI) day 15 in each of 5 experimentally infected animals. Importantly, detectable antibody persisted in all carrier animals without a significant decrease in optical density through 12 mo PI, at which time the experiment was terminated. The results indicate that immunodominant epitopes expressed by a single gene copy of msa-1 do not undergo marked antigenic shift typical of the gene family during the course of a single infection in the mammalian host. The results are compatible with the limited MSA-1 polymorphism reported in some geographically defined endemic populations.
authors.affiliation: Department of Veterinary Microbiology and Pathology, Washington State University, Pullman 99164-7040, USA.
authors.forename: T F
authors.initials: TF
authors.lastname: McElwain
authors.forename: S A
authors.initials: SA
authors.lastname: Hines
authors.forename: G H
authors.initials: GH
authors.lastname: Palmer
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology; D016793:Babesia bovis / Q000235:genetics / Q000276:immunology*; D001404:Babesiosis / Q000276:immunology*; D002353:Carrier State / Q000276:immunology / Q000662:veterinary*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology*; D002846:Chromatography, Affinity / Q000662:veterinary; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D020066:Merozoite Surface Protein 1; D011498:Protein Precursors / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000954:Antigens, Surface; D000939:Epitopes; D020066:Merozoite Surface Protein 1; D011498:Protein Precursors; D015800:Protozoan Proteins; D011994:Recombinant Proteins