Immulectin-2 from the ghost moth, Thitarodes xiaojinensis (Lepidoptera: Hepialidae), modulates cellular and humoral responses against infection

C type-lectins constitute a large family of pattern recognition receptors, playing important roles in insect immune defenses. Thitarodes xiaojinensis larvae showed distinct immune features after Ophiocordyceps sinensis, Cordyceps militaris, or Beauveria bassiana infection. Based on transcriptome and immunoblot analysis, we found that immulectin-2 (IML2) was induced after T. xiaojinensis larvae were infected by C. militaris or B. bassiana but maintained at a low level after larvae injected with O. sinensis or Ringer's buffer. Recombinant IML2 (rIML2) could promote melanization, encapsulation, phagocytosis, and hemocyte aggregation in vitro. RNA interference with IML2 induced a significant reduction in the transcript levels of various antimicrobial peptides. Importantly, we found that the abundance of O. sinensis blastospores coated with rIML2 dramatically decreased in the host hemolymph. Overall, this study demonstrated that T. xiaojinensis IML2 modulates cellular and humoral responses to entomopathogenic fungi, broadening our view of the immune interaction between O. sinensis and its host.

Automated summary

This study revealed that immulectin-2 (IML2) in Thitarodes xiaojinensis larvae is induced after infection by Cordyceps militaris or Beauveria bassiana but maintained at a low level after infection by Ophiocordyceps sinensis or Ringer's buffer. Recombinant IML2 (rIML2) can promote melanization, encapsulation, phagocytosis, and hemocyte aggregation. RNA interference with IML2 reduces the transcript levels of various antimicrobial peptides. Importantly, the abundance of O. sinensis blastospores coated with rIML2 dramatically decreases in the host hemolymph.