BABESIA-BOVIS - BIOSYNTHESIS AND LOCALIZATION OF THE 12D3 ANTIGEN IN BOVINE ERYTHROCYTES

The 12D3 antigen of Babesia bovis was found to be synthesised rapidly in cultured parasites, and localised to both the apical complex of the merozoite and the cytoplasm of the parasitised erythrocyte. Amino-ter minal sequencing suggested that the nascent protein had been processed and differences between the predicted and measured molecular weights suggested post-translational modification. The major proportion of 12D 3 appeared in the soluble compartment of the parasitised erythrocytes with a molecular weight consistent with no further processing. A signi ficant proportion of the protein required extraction by sodium carbona te, suggesting association with membranous components. The timing of r elease of soluble 12D3 was coincident with haemoglobin release and thi s probably reflects a non-specific lysis of the erythrocyte. Synthesis of recombinant BV12D3 was achieved in baculovirus-infected SF9 insect epithelial cells. The product was of the same molecular weight as the native 12D3 and polyclonal antibodies raised against the recombinant protein reacted with both the recombinant and native forms of the anti gen. Copyright (C) 1996 Australian Society for Parasitology. Published by Elsevier Science Ltd.