Morphological, serological and antigenic characteristics, and protein profile of newly isolated Japanese bovine Babesia parasite with particular reference to those of B. ovata.

An intraerythrocytic large protozoan, tentatively designated Babesia sp. 1, was recently isolated from cattle in Hokkaido Prefecture, Japan. This parasite closely resembled B. ovata in shape of piroplasms, but was distinguishable by other morphological, immunological, and biochemical characters. The paired pyriform piroplasm of B. sp. 1 was larger than that of B. ovata. The results from serological and antigenic examination by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis showed that there were cross- but distinguishable-reaction between B. sp. 1 and B. ovata. Protein profiles of both Babesia parasites piroplasms analyzed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) were apparently different from each other. Several major proteins revealed by 2D-PAGE and the immunodominant proteins resolved by Western blot analysis (40 kDa for B. sp. 1 and 29 kDa for B. ovata) were unique to each parasite. The results of the present study indicate the possibility that B. sp. 1 is a species different from B. ovata.