Identification of a hemolin protein from Actias selene mediates immune response to pathogens

Hemolins play an important role in development and innate immunity in insects. In this study, a hemolin cDNA of 1412bp in Actias selene (As-HEM) was isolated and its open reading frames (ORFs) were 420 amino acid residues. Sequence analysis indicated As-HEM was homologous to those hemolins from other insects species. The recombinant protein of As-HEM was expressed in Escherichia coli, and anti-As-HEM antibodies were prepared. Real-time quantitative PCR (RT-qPCR) and western blot results revealed that mRNA and protein levels of As-HEM were mostly detected in hemocytes and hemolymph. Immune challenge assays showed that both the mRNA and protein levels of As-HEM could be induced significantly post Beauveria bassiana, E. coli, Micrococcus luteus and nuclear polyhedrosis virus challenges. Agglutination assays revealed that recombinant As-HEM could promote the agglutination of E. coli in the presence of calcium. Our results suggested that As-HEM was involved in the innate immunity of A. selene.