Babesia bovis expresses Bbo-6cys-E, a member of a novel gene family that is homologous to the 6-cys family of Plasmodium

Authors: Gomes Da Silva, Marta; Ueti, Massaro; NORIMINE, JUNZO - Washington State University; FLORIN-CHRISTENSEN, MONICA - Instituto Nacional Tecnologia Agropecuaria; BASTOS, REGINALDO - Washington State University; GOFF, W - US Department Of Agriculture (USDA); BROWN, WENDY - Washington State University; OLIVA, ABEL - Instituto De Biologia; Suarez, Carlos

Submitted to: Parasitology International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2010
Publication Date: N/A
Citation: N/A

Interpretive Summary: This manuscript describes the identification of a Babesia bovis gene family encoding for six proteins containing a 6cys motif that is present in sexual stage proteins of Plasmodium. One of encoded proteins, homologous to PFS230 from Plasmodium falciparum, is expressed in blood stages of the parasite and contains neutralization sensitive B-cell epitopes, suggesting functional relevance for the survival of the parasite. Identification of this new gene family in B.bovis and further investigation on its biological significance may aid our understanding of the bovine, tick and parasite relationships and the development of improved control methods against B. bovis infection in cattle.

Technical Abstract: A novel Babesia bovis gene family encoding proteins with similarities to the Plasmodium 6cys protein family was identified by TBLASTN searches of the Babesia bovis genome using the sequence of the P. falciparum PFS230 protein as query, and was termed Bbo-6cys gene family. The Bbo-cys6 gene family contains six genes termed Bbo-6cys-A, B, C, D, E and F encoding for proteins containing an arrangement of 6 cysteine residues. The Bbo-6cys genes A, B, C, D, and E are tandemly arranged as a cluster of Chromosome 2 in the B. bovis genome, whereas gene F is located in a distal region in the same chromosome. The Bbo-6cys-E gene, with higher homology to PFS230, was selected for further examination. Immunoblot analysis using recombinant Bbo-6cys-E protein and B. bovispositive bovine serum demonstrated expression by the parasite and immunogenicity during B. bovis infection. Immunofluorescence analysis using anti-Bbo-6cys-E antibodies confirmed expression of Bbo-6cys-E in in vitro blood stages of B. bovis. In addition, polyclonal antisera against both recombinant Bbo-6cys-E and specific synthetic peptides containing predicted B-cell epitopes of Bbo-6cys-E, significantly inhibited erythrocyte invasion by B. bovis in in vitro neutralization assays, suggesting an important functional role for this protein. Identification of this new gene family in B. bovis and further investigation on its biological significance may aid our understanding of the bovine, tick and parasite relationships and the development of improved control methods against B. bovis infection in cattle.