<i>Babesia Bovis</i> Ligand-Receptor Interaction: AMA-1 Contains Small Regions Governing Bovine Erythrocyte Binding

• Main Authors: Laura Cuy-Chaparro, Michel David Bohórquez, Gabriela Arévalo-Pinzón, Jeimmy Johana Castañeda-Ramírez, Carlos Fernando Suárez, Laura Pabón, Diego Ordóñez, Gina Marcela Gallego-López, Carlos Esteban Suárez, Darwin Andrés Moreno-Pérez, Manuel Alfonso Patarroyo
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Babesia bovis</i>; AMA-1; minimum region; adhesion; bovine erythrocyte; synthetic vaccine
• Online Access: https://www.mdpi.com/1422-0067/22/2/714

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 <i>Babesia bovis</i>. This study was focused on identifying the minimum <i>B. bovis</i> AMA-1-derived regions governing specific and high-affinity binding to its target cells. Different approaches were used for detecting <i>ama-1</i> 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-iodination. <i>B. bovis</i> AMA-1 ectodomain structure was modelled and refined using molecular modelling software. NetMHCIIpan software was used for calculating B- and T-cell epitopes. The <i>B. bovis ama-1</i> gene had regions under functional constraint, having the highest negative selective pressure intensity in the Domain I encoding region. Interestingly, <i>B. bovis</i> 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 appear to be exposed on the protein’s surface and contain predicted B- and T-cell epitopes. These findings provide data (for the first-time) concerning <i>B. bovis</i> AMA-1 functional subunits which are important for establishing receptor-ligand interactions which could be used in synthetic vaccine development.