Vitellogenin regulates antimicrobial responses in Chinese mitten crab, Eriocheir sinensis

Vitellogenin (Vtg) is traditionally regarded as a key supplier of nutrients and energy during the early development of embryos and larvae, but accumulating evidence suggests that Vtg is also involved in innate immune defense. Whether Vtg is involved in innate immunity in Eriocheir sinensis, and its functions, remain largely unknown. In this study, a cDNA representing the vitellogenin1 gene from E. sinensis (Es-vtg1) was cloned. The full-length Es-vtg1 cDNA comprised 7939 nucleotides, encoding an open-reading frame of 2567 amino acid residues. Bioinformatic analysis showed that the domains of Es-Vtg1 have been conserved during evolution. Quantitative real-time PCR and western blotting showed that Es-vtg1 was highly expressed in ovary and hepatopancreas. Moreover, bacteria could induce the high-level expression of Es-Vtg1. Es-Vtg1 plays important roles in immunological defense, including binding to bacteria, inhibiting bacterial proliferation, and regulating the expression of antimicrobial peptides. Collectively, these results demonstrate that Es-Vtg1 plays critical roles in antimicrobial function.