Conservation of the sporozoite p67 vaccine antigen in cattle-derived Theileria parva stocks with different cross-immunity profiles.
Immunity to Theileria parva infection in cattle is often parasite stock specific. The antigenic diversity which is expressed at the schizont stage of the parasite together with a wild reservoir of the organism in buffalo has complicated the development of effective disease control by immunization. We have previously shown that about 70% of cattle inoculated with recombinant forms of p67, a sporozoite stage-specific surface antigen from the cattle-derived Muguga stock of the parasite, are immune to a homologous challenge. Thus, immune responses to p67 can play a role in immunity. The genes encoding this protein in five other parasite stocks have been sequenced. Here, we report that the p67 molecule encoded by four cattle-derived parasite stocks (Boleni, Uganda, Mariakani, and Marikebuni) that fall into different cross-immunity groups is identical in sequence to Muguga p67. The protein encoded by a buffalo-derived parasite exhibits 95% sequence identity with Muguga p67, the major difference being the presence of a 43-residue peptide insert. As predicted by these data, cattle inoculated with recombinant p67 can resist a heterologous cattle-derived parasite challenge. Seven of 12 cattle receiving a homologous Muguga challenge and 6 of 11 cattle receiving a heterologous Marikebuni challenge were immune to East Coast fever. These results extend earlier data suggesting that p67 is a conserved molecule and confirm its potential as a broad-spectrum vaccine antigen for the control of T. parva infection.
Nene
V
V
International Livestock Research Institute, Nairobi, Kenya.
Musoke
A
A
Gobright
E
E
Morzaria
S
S
D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D002417:Cattle; D003429:Cross Reactions; D008969:Molecular Sequence Data; D016052:Protozoan Vaccines / Q000235:genetics / Q000276:immunology*; D016797:Theileria parva / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000276:immunology*
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016052:Protozoan Vaccines; D014614:Vaccines, Synthetic