CHI3L2 and biological process involved in symbiotic interaction: These are in consistence with our EmiChIL-2 model, where ChIL-2 was driven by an actin promoter, a house-keeping gene promoter, guaranting that ChIL-2 was expressed and secreted into the parasite infection immune microenvironment continuously during the whole life cycle (Zou et al., 2009; Yin et al., 2011).