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Title: A Babesia bovis gene syntenic to Theileria parva p67 is expressed in blood and tick stage parasites

Author
item Freeman, Jeanne
item Kappmeyer, Lowell
item Ueti, Massaro
item MCELWAIN, TERRY - Washington State University
item BASZLER, TIMOTHY - Washington State University
item ECHAIDE, IGNACIO - Instituto Nacional Tecnologia Agropecuaria
item NENE, VISHVANATH - International Centre Of Insect Physiology And Ecology
item Knowles Jr, Donald

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2010
Publication Date: 10/29/2010
Citation: Freeman, J.M., Kappmeyer, L.S., Ueti, M.W., Mcelwain, T.F., Baszler, T.V., Echaide, I., Nene, V.M., Knowles Jr, D.P. 2010. A Babesia bovis gene syntenic to Theileria parva p67 is expressed in blood and tick stage parasites. Veterinary Parasitology. 173(3-4):211-218.

Interpretive Summary: Based on synteny, we identified loci in B. bovis, B. equi, and B. bigemina corresponding to the p67 locus of T. parva. There are six syntenic genes in this locus. While gene order is conserved between Babesia sp. and T. parva, sequence identity between p67 and the corresponding gene is lacking. We characterized the syntenic gene to p67 in B. bovis, which we have designated bov57, in the tick transmissible strain T2Bo by 1) testing for the presence of transcripts in tick and cultured blood stages, as well as verifying transcript length as predicted by the genome; 2) comparing transcript levels to a known surface protein encoding gene; and 3) verifying expression in cultured blood stages using monoclonal antibodies developed against the recombinant protein. In addition, amino acid sequence comparisons of syntenic genes in other B. bovis strains as well as B. equi and B. bigemina were performed to evaluate the level of sequence conservation within B. bovis strains and between other Babesia species.

Technical Abstract: Completion of the Babesia bovis (T2Bo strain) genome provides detailed data concerning the predicted proteome of this parasite, and allows for a bioinformatics approach to gene discovery. Comparative genomics of the hemoprotozoan parasites B. bovis and Theileria parva revealed a highly conserved syntenic block of genes flanking the p67 gene of T. parva, a sporozoite stage-specific vaccine candidate against East Coast fever (ECF). The syntenic gene in B. bovis, designated bov57, encodes a protein of limited amino acid sequence identity (11.8%) to p67. Monoclonal antibodies were produced against recombinant BOV57 and were used to demonstrate expression of BOV57 in merozoite and kinete stages of the T2Bo strain of B. bovis. Transcript levels of bov57 in kinetes were increased 100-fold in comparison to msa-1, a previously identified gene encoding an erythrocyte stage surface protein. Amino acid sequence comparisons between the T2Bo strain and two attenuated and virulent strains from Argentina and Australia revealed a high degree of sequence conservation in BOV57 among these geographically and pathogenically divergent isolates (97% amino acid sequence identity. Additional genomic comparisons show that the bov57 gene locus is also conserved in B. bigemina and B. equi. While not identifiable through amino acid or nucleotide sequence homology, the conserved gene order within this locus in multiple piroplasms suggests a critical function adapted for each species’ unique host and life-cycle.