Babesia bovis ligand-receptor interaction: AMA-1 contains small regions governing bovine erythrocyte binding

Authors: CUY-CHAPARRO, LAURA - Colobmbian Institute Of Immunology Foundation(FIDIC); BOHÓRQUEZ, MICHEL - Colobmbian Institute Of Immunology Foundation(FIDIC); ARÉVALO-PINZÓN, GABRIELA - Colobmbian Institute Of Immunology Foundation(FIDIC); CASTAÑEDA-RAMÍREZ, JEIMMY - Colobmbian Institute Of Immunology Foundation(FIDIC); SUAREZ, CARLOS - Colobmbian Institute Of Immunology Foundation(FIDIC); PABON, LAURA - Colobmbian Institute Of Immunology Foundation(FIDIC); ORDOÑEZ, DIEGO - Colobmbian Institute Of Immunology Foundation(FIDIC); GALLEGO-LÓPEZ, GINA - University Of Wisconsin; Suarez, Carlos; MORENO-PÉREZ, DARWIN - Colobmbian Institute Of Immunology Foundation(FIDIC); PATARROYO, MANUEL - Colobmbian Institute Of Immunology Foundation(FIDIC)

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/31/2020
Publication Date: 1/13/2021
Citation: Cuy-Chaparro, L., Bohórquez, M.D., Arévalo-Pinzón, G., Castañeda-Ramírez, J.J., Suarez, C.F., Pabon, L., Ordoñez, D., Gallego-López, G.M., Suarez, C.E., Moreno-Pérez, D.A., Patarroyo, M.A. 2021. Babesia bovis ligand-receptor interaction: AMA-1 contains small regions governing bovine erythrocyte binding. International Journal of Molecular Sciences. 22(2). Article 714. https://doi.org/10.3390/ijms22020714.
DOI: https://doi.org/10.3390/ijms22020714

Interpretive Summary: Babesia bovis is a tick-borne intraerythrocytic parasite responsible for bovine babesiosis. Apical membrane antigen 1 is a parasite protein which plays an indispensable role during erythrocyte invasion by the parasite. Undefined regions in the Babesia bovisAMA-1 interact with a still uncharacterized receptor on bovine erythrocytes. This study focuses on identifying 3 peptides derived from B. bovisAMA-1 governing specific and high affinity binding to the AMA-1 receptor in bovine erythrocytes. Importantly the peptides include regions that are potentially immunogenic. These regions can be exploited in the future for developing synthetic vaccines that can generate antibodies able to block the entry of the parasite to the bovine erythrocytes.

Technical Abstract: Apical membrane antigen 1 is a microneme protein which plays an indispensable role during Apicomplexa parasite invasion. The detailed mechanism of AMA-1 molecular interaction with its receptor on bovine erythrocytes has not been completely defined in Babesia bovis. This study focuses on identifying the minimum B. bovis AMA-1-derived regions governing specific and high affinity binding to its target cells. Different approaches were used for detecting AMA-1 locus genetic variability and natural selection signatures. The binding properties of twelve highly conserved 20-residue-long peptides were evaluated using a sensitive and specific binding assay based on radio-ionidation. B. bovis AMA-1 ectodomain structure was modelled and refined using molecular modelling software. NetMHCIIpan software was used for calculating B- and T-cell epitopes. The B. bovis ama-1 gene had regions under functional constraint, having the highest negative selective pressure intensity in the DI encoding region. Interestingly, B. bovis AMA-1-DI (100YMQKFDIPRNHGSGIYVDLG119 and 120GYESVGSKSYRMPVGKCPVV139) and DII (302CPMHPVRDAIFGKWSGGSCV321)-derived peptides had high specificity interaction with erythrocytes and bound to a chymotrypsin and neuraminidase-treatment sensitive receptor. DI-derived peptides were exposed to surface proteins and contain predicted B- or T-cell epitopes. These findings provide data (for the first-time) concerning B. bovis AMA-1 functional subunits which are important for establishing receptor-ligand interactions which could be used in synthetic vaccine development.