2021 Fiscal Year Annual Research Report
Functional characterization of Babesia bovis proteins expressed on the surface of infected erythrocytes- Toward identification of novel vaccine and therapeutic candidates
| Project/Area Number |
19K15983
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| Research Institution | Obihiro University of Agriculture and Veterinary Medicine |
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Principal Investigator |
晴希生 ハッサン 帯広畜産大学, 原虫病研究センター, 特任研究員 (80745183)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | Babesia bovis / Surface proteins / Protein export / Vaccine / Therapeutic target |
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| Outline of Annual Research Achievements |
Using proteomics we identified of 3 novel exported proteins: The first two protein (Bb60 and Bb11920) with 10 transmembrane regions that were expressed in spherical bodies and on the surface of infected red blood cells (iRBCs). BLAST (Basic Local Alignment Search Tool) searches in PiroplasmaDB clarified that these proteins encoded by a novel multigene family with 44 copies which we named as "mtm". Because another RBC infecting parasite, Plasmodium falciparum, was shown to become blasticidin S (BS) resistant by decreasing anion channel activity on iRBC, we generated BS-resistant B. bovis to confirm whether this protein may serve as a channel. Development of BS resistance resulted in downregulation of one major expressing gene of mtm, suggesting an association with BS uptake.
Induced knockdown of the third exported protein, Bb4280, using the glmS riboswitch system resulted in decreased growth rate, reduced ridge
numbers on the erythrocyte surface, mislocalized VESA1 (Variant Erythrocyte Surface Antigen 1) that is a ligand for cytoadhesion, and abrogated
cytoadhesion to endothelial cells, suggesting that this protein is a novel virulence factor for B. bovis. We named this protein VESA1-export associated protein (BbVEAP). We established a method for isolation of viable and invasive B. bovis merozoites. Induced knockdown of BbVEAP did not affect merozoite invasion into RNC but arrested parasite development suggesting an essential role of BbVEAP during development in the RBC.
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