A novel 20-kilodalton protein conserved in Babesia bovis and B. bigemina stimulates memory CD4(+) T lymphocyte responses in B. bovis-immune cattle.

Authors used cDNA from Babesia bovis Mex to obtain a sequence that was also shared with genomic DNA from an unidentified Babesia bovis strain. Mouse anti-sera against the epitope reacted with the heterospecific 20 kDa antigen (Bbg 20) from an infected erythrocyte cell membrane fraction on a Western blot. Reactivity was also seen against the Bbg 20 from three other strains of B. bigemina: Texcoco, St. Croix, and Puerto Rico. The homologous epitope region in B. bigemina has the sequence KNHDYTEKPS. A recombinant form of Bbg 20 containing additional amino acids and a his tag also reacted.