Identification and Immunological Characterization of Annexin B8 and Annexin E1 from Spirometra Erinaceieuropaei Spargana.

Sparganosis is a parasitic zoonotic disease that poses a serious threat to public hygiene and human health. Annexin is a phospholipid-binding protein with calcium ion binding activity, serving various important functions, including interaction with the parasite and regulation of the host's immune response. In this study, two annexin (ANX) family genes, Spirometra erinaceieuropaei (S. erinaceieuropaei) Annexin B8 (SeANXB8) and E1 (SeANXE1), isolated from spargana, were cloned and immunologically characterized. Both recombinant S. erinaceieuropaei Annexin B8 (rSeANXB8) and E1 (rSeANXE1) were specifically recognized by serum from rats immunized with the recombinant proteins, displaying strong immunoreactivity. They are also among the major components of sparganum excretion/secretion products (ESPs). SeANXE1 was identified in the parasite's tegument, testis, genital pore, ovary, and eggs, while SeANXB8 was found in the parasite's tegument and eggs. Plasminogen (PLG)-binding assays revealed that the two annexins could bind to human PLG in a concentration-dependent manner, which was blocked by the corresponding antibodies. These findings suggest that SeANXB8 and SeANXE1 may be involved in host-parasite interaction and may influence the host's immune response during sparganosis. They could be potential diagnosis and vaccination targets for sparganosis.