A PCR based survey of Babesia ovata in cattle from various Asian, African and South American countries.

Babesia ovata is a tick-transmitted hemoprotozoan parasite that infects cattle. In our study, bovine blood samples (n=2,034) were collected from 10 different countries (Brazil, China, Ghana, Japan, Mongolia, the Philippines, South Africa, Sri Lanka, Thailand and Vietnam) and DNA extracted. The DNA samples were screened using an established and specific polymerase chain reaction (PCR) assay targeting the Apical membrane antigen 1 (AMA-1) gene. Parasite DNA was detected among samples collected from Japan, Mongolia and Thailand. Sequence analyses confirmed that the PCR assay detected only B. ovata AMA-1, and that amplicons from different geographical locations were conserved. Our findings highlight the importance of designing adequate strategies to control B. ovata infection in Japan, Mongolia, and Thailand.

Expression and immunological characterization of the heat shock protein-70 homologue from Babesia bigemina.

The Babesia bigemina heat shock protein-70 gene (BbigHSP-70) was cloned from cDNA by polymerase chain reaction (PCR) and sequenced. The length of the gene is 1947 bp and the predicted polypeptide is 649 amino acids long with a calculated molecular weight of 70.85 kDa. BbigHSP-70 has a signal peptide of 15 amino acids. Phylogenetic analysis of the amino acid sequence of BbigHSP-70 showed that B. bigemina was most closely related to B. caballi and B. bovis and lies within a phylogenetic cluster with Theileria. rBbigHSP-70 was expressed in E. coli as a soluble GST-fusion protein with a molecular mass of 96.8-kDa. The serum raised in mice against rBbigHSP-70 detected the native protein in B. bigemina, B. bovis, B. caballi, B. gibsoni, and B. microti lysates and also reacted with B. bigemina, B. bovis, and B. caballi merozoites in the IFAT. Mice vaccinated with rBbigHSP-70 showed lower parasitemia against the challenge infection with B. microti than GST-vaccinated and non-vaccinated controls. These results added a new member of Babesia heat shock proteins70 that is well conserved among intraerythrocytic protozoa and demonstrated its protective effects in an experimental model of rodent babesiosis.