Drosophila Niemann–Pick disease type C2 (NPC2) proteins play roles in sterol homeostasis, steroid biosynthesis,and innate immune signaling pathways. In this study, a bee (Apis cerana) NPC2a protein (AcNPC2a) that mightfunction in innate immune reactions was identified. AcNPC2a consisted of 148 amino acids, which included sixconserved cysteine residues. Recombinant AcNPC2a protein (expressed in baculovirus-infected insect cells)bound directly to live Escherichia coli, Bacillus thuringiensis, and Beauveria bassiana; however, AcNPC2a did notshow antimicrobial activity against these microorganisms. Nevertheless, the expression of AcNPC2a was significantlyinduced in the fat body of A. cerana worker bees after injection with E. coli, B. thuringiensis, or B. bassiana. Our data suggest a role for AcNPC2a in innate immunity that is induced in response to microbial challenge andbinds directly to the cell walls of bacteria and fungi. These findings provide insight into the role of AcNPC2aduring the innate immune response following bacterial and fungal infection.