Purification and characterization of a 1,3-β-D-glucan recognition protein from Antheraea pernyi larve that is regulated after a specific immune challenge

Pattern recognition receptors are known to participate in the activation of Prophenoloxidase system. In this study, a 1,3-β-D-glucan recognition protein was detected for the first time in Antheraea pernyi larvae (Ap-βGRP). Ap-βGRP was purified to 99.9% homogeneity from the hemolymph using traditional chromatographic methods. Ap-βGRP specifically bind 1,3-β-D-glucan and yeast, but not E. coli or M. luteus. The 1,3-β-D-glucan dependent phenoloxidase (PO) activity of the hemolymph inhibited by anti-Ap-βGRP antibody could be recovered by addition of purified Ap-βGRP. These results demonstrate that Ap-βGRP acts as a biosensor of 1,3-β-Dglucan to trigger the Prophenoloxidase system. A trace mount of 1,3-β-D-glucan or Ap-βGRP alone was unable to trigger the proPO system, but they both did. Ap-βGRP was specifically degraded following the activation of proPO with 1,3-β-Dglucan. These results indicate the variation in the amount of Ap-βGRP after specific immune challenge in A. pernyi hemolymph is an important regulation mechanism to immune response.