Steroid hormone 20 ‐hydroxyecdysone promotes CTL1‐mediated cellular immunity in Helicoverpa armigera

A proposed model for the induction of HaCTL1 upon 20E signaling, thereby promoting cellular immunity. 20E ‐HaEcR‐HaUSP complex induces the expression ofHaCTL1 in hemocytes, followed by the secretion of HaCTL1 into the hemocoel. HaCTL1 then recognizes pathogens (such as parasitic nematodes and bacteria) and interacts with the unknown hemocytic receptor, which then activates cellular immune reactions such as encapsulation and phagocytosis. AbstractMermithid nematodes, such asOvomermis sinensis, are used as biological control agents against many insect pests, including cotton bollworm (Helicoverpa armigera). However, given the host's robust immune system, the infection rate ofO.sinensis is low, thus restricting its widespread use. To understand the host defense mechanisms against mermithid nematodes, we identified and characterized a protein involved in the recognition ofO.sinensis, the potentialO.sinensis‐binding protein C‐type lectin 1 (HaCTL1a and/or HaCTL1b), which was eluted from the surface ofO. sinensis after incubation withH.armigera plasma. HaCTL1b is homologous to the previously reported HaCTL1a protein. HaCTL1 was predominantly expressed in hemocytes and was induced by the steroid hormone 20 ‐hydroxyecdysone through ecdysone receptor (HaEcR) or ultraspiracle (HaUSP), or both. Binding assays confirmed the interactions of the HaCTL1 proteins withO.sinensis but not withRomanomermis wuchangensis, a parasitic nematode of mosquito. Moreover, the HaCTL1 proteins we...
Source: Insect Science - Category: Biology Authors: Tags: ORIGINAL ARTICLE Source Type: research