title: Babesia bovis merozoite surface antigen 2 proteins are expressed on the merozoite and sporozoite surface, and specific antibodies inhibit attachment and invasion of erythrocytes.
abstract: The Babesia bovis merozoite surface antigen 2 (MSA-2) locus encodes four proteins, MSA-2a(1), -2a(2), -2b, and -2c. With the use of specific antibodies, each MSA-2 protein was shown to be expressed on the surface of live extracellular merozoites and coexpression on single merozoites was confirmed. Individual antisera against MSA-2a, MSA-2b, and MSA-2c significantly inhibited merozoite invasion of bovine erythrocytes. As tick-derived sporozoites also directly invade erythrocytes, expression of each MSA-2 protein on the sporozoite surface was examined and verified. Finally, statistically significant inhibition of sporozoite binding to the erythrocytes was demonstrated by using antisera specific for MSA-2a, MSA-2b, and MSA-2c. These results indicate an important role for MSA-2 proteins in the initial binding and invasion of host erythrocytes and support the hypothesis that sporozoites and merozoites use common surface molecules in erythrocyte invasion.
authors.affiliation: Program in Vector-Borne Diseases, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164-7040, USA. mosjj@vetmed.wsu.edu
authors.forename: Juan
authors.initials: J
authors.lastname: Mosqueda
authors.forename: Terry F
authors.initials: TF
authors.lastname: McElwain
authors.forename: Guy H
authors.initials: GH
authors.lastname: Palmer
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology*; D000953:Antigens, Protozoan / Q000032:analysis* / Q000276:immunology; D016793:Babesia bovis / Q000276:immunology*; D002417:Cattle; D004912:Erythrocytes / Q000469:parasitology*; D020066:Merozoite Surface Protein 1 / Q000032:analysis; D051379:Mice; D015800:Protozoan Proteins / Q000032:analysis* / Q000276:immunology; D011817:Rabbits; D034101:Sporozoites / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium