Invasion Into Hemocytes Is Mediated by Pathogen Enolase and Host Lipopolysaccharide and β-1, 3-Glucan Binding Protein.

is a crustacean pathogen, without a cell wall, that causes enormous economic loss. hemocytes are the major targets during infection. As wall-less bacteria, , its membrane protein should interact with host membrane protein directly and firstly when invaded in host cell. In this investigation, six potential hemocyte receptor proteins were identified firstly that mediate interaction between and . Among these proteins, lipopolysaccharide and β-1, 3-glucan binding protein (MrLGBP) demonstrated to bind to using bacterial binding assays and confocal microscopy. Four spiroplasma ligand proteins for MrLGBP were isolated and identified. But, competitive assessment demonstrated that only enolase of (SeEnolase) could be a candidate ligand for MrLGBP. Subsequently, the interaction between MrLGBP and SeEnolase was confirmed by co-immunoprecipitation and co-localization . After the interaction between MrLGBP and SeEnolase was inhibited by antibody neutralization test, the virulence ability of was effectively reduced. The quantity of decreased in S2 cells after overexpression of , compared with the controls. In addition, RNA interference (RNAi) knockdown of made more sensitive to infection. Further studies found that the immune genes, including and (), , and α were significantly up-regulated by SeEnolase stimulation. After SeEnolase pre-stimulation, the ability of resistance to was significantly improved. Collectively, this investigation demonstrated that MrLGBP and pathogen SeEnolase involved in mediating invasion into hemocytes.