Characterization of the gene encoding a 60-kilodalton Babesia bovis merozoite protein with conserved and surface exposed epitopes.
A clone expressing a surface exposed, conserved epitope of a 60-kDa merozoite polypeptide was identified in a cDNA library constructed from a cloned Mexico strain of Babesia bovis. Sequencing of the 1.9-kb insert (pBv60) revealed an open reading frame encoding a 65-kDa polypeptide with a signal peptide and a tandemly repeated region. Monoclonal antibody 23/56.156, which binds a surface exposed epitope on the native polypeptide, specifically immunoprecipitated [35S]methionine-labeled polypeptides ranging from 60-30 kDa from pBv60 directed transcription and translation. Antibodies raised in rabbits against recombinant polypeptide reacted with the live merozoite surface in a polar immunofluorescence pattern, immunoprecipitated the native 60-kDa polypeptide, and were used to deplete the polypeptide by adsorption from a preparation of native [35S]methionine-labeled merozoite antigen. Restriction enzyme analysis indicated a single gene copy and the absence of introns. Hybridization demonstrated the presence of the gene in Mexico, Australia 'L', and Texas strains of B. bovis, but not in Babesia bigemina. A slightly different hybridization pattern was present in uncloned Australia 'L' B. bovis, indicating sequence diversity in the Bv60 gene among isolates. Cloning and structural analysis of pBv60 provides a source of defined antigen for determining the role of conserved merozoite surface epitopes in protective immunity against babesiosis.
Suarez
C E
CE
Department of Veterinary Microbiology and Pathology, Washington State University, Pullman.
Palmer
G H
GH
Jasmer
D P
DP
Hines
S A
SA
Perryman
L E
LE
McElwain
T F
TF
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics*; D000954:Antigens, Surface / Q000235:genetics*; D001403:Babesia / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D016054:DNA, Protozoan; D000939:Epitopes; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011233:Precipitin Tests; D016415:Sequence Alignment
D000953:Antigens, Protozoan; D000954:Antigens, Surface; D016054:DNA, Protozoan; D000939:Epitopes