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

► A multigene family with Plasmodium 6-cys domain present in related Apicomplexa. ► The sequence of the Bbo-6cys-E protein is conserved among distinct B. bovis strains. ► The Bbo-6cys-E protein is expressed during B. bovis infection and is antigenic. ► Significant reduction of erythrocyte invasion with anti-rBbo-6cys-E antisera. ► Bbo-6cys-E protein is a strong candidate for subunit vaccine.