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

•We firstly identified an immunoglobulin family protein Hemolin from Actias selene (As-HEM).•We proved that As-HEM can mediates immune response to pathogens in Actias selene.•As-HEM can be induced by Beauveria bassiana, Escherichia coli, Micrococcus luteus and nuclear polyhedrosis virus.•Agglutination test showed that As-HEM could agglutinate E. coli.

Hemolins play an important role in development and innate immunity in insects. In this study, a hemolin cDNA of 1412 bp 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.

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