Vaccine development against Theileria parasite.
Bovine piroplasmosis caused by Theileria sergenti is a major cause of economical loss in grazing cattle in Japan. We found that parasite stocks and isolates consist of genetically and antigenically mixed population. To differentiate parasite populations bearing 2 allelic forms of p32, an immunodominant piroplasm surface protein, 2 sets of oligonucleotide primers were designed to amplify either of the 2 alleles by polymerase chain reaction (PCR). By using this allele-specific PCR, we found that the majority of T. sergenti-infected calves in Japan harbored mixed parasite populations with C and I type parasites. Amino acid sequence of p32 contains Lys-Glu-Lys (KEK) motif which is one of tripeptide necessary for malaria parasite to invade erythrocytes. We produced 2 vaccine candidates, recombinant baculovirus p32 and synthetic peptide containing KEK motif. Immunization of either recombinant p32 or synthetic peptide containing a KEK sequence with adjuvant resulted in low parasitemia and reduced the clinical symptoms compared to control calves. Interestingly, parasites with a p32 allelic form corresponding to one used as the immunogen were suppressed. Therefore, a cocktail vaccine containing KEK peptides derived from C and I type parasites is desired for control Theileria parasite infection in Japan.
Onuma
M
M
Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Kubota
S
S
Kakuda
T
T
Sako
Y
Y
Sugimoto
C
C
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology; D002417:Cattle; D016056:Immunodominant Epitopes / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D018512:Parasitemia / Q000517:prevention & control; D010446:Peptide Fragments / Q000276:immunology; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D016052:Protozoan Vaccines / Q000276:immunology; D016794:Theileria / Q000276:immunology*; D013801:Theileriasis / Q000517:prevention & control*; D014611:Vaccination; D014614:Vaccines, Synthetic / Q000276:immunology
D000953:Antigens, Protozoan; D016056:Immunodominant Epitopes; D008565:Membrane Proteins; D010446:Peptide Fragments; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D014614:Vaccines, Synthetic; C085175:piroplasm surface protein p32, Theileria sergenti