Abstract:In this study, we investigated the effect of pathogenic Enterococcus faecalis challenge on the non-specific immunity-related gene expression of Exopalaemon carinicauda. The expression levels of prophenoloxidase (proPO), C-type lectin (CTL), superoxide dismutase (SOD), cathepsin D (Cat D) and cathepsin L (Cat L) in hemocytes and hepatopancreas were measured with quantitative real-time PCR at different sampling time points after healthy E. carinicauda were injected with 0.86% sterile saline (control) or pathogenic E. faecalis. Compared to the control group, after infected with E. faecalis, the relative expression levels of proPO gene in hemocytes and hepatopancreas both increased to the highest at 6 h (P<0.05), and then decreased gradually back to normal. The relative expression levels of CTL gene in hemocytes and hepatopancreas increased to the peak value at 12 h and 6 h respectively (P<0.05), and then decreased gradually. Although the relative expression levels of CTL gene in hemocytes decreased at 72 h, it was still significantly higher than the control (P<0.05). The relative expression levels of SOD gene in hemocytes and hepatopancreas both increased to the highest at 6 h and 3 h respectively (P<0.05), then decreased gradually back to normal at 72 h. The dynamic expression of Cat D gene in hemocytes and hepatopancreas was consistent, which was a significant decreased in the beginning followed by an increase. After the decrease of expression at 12 h, it was increased significantly again. The Cat L gene expression in hemocytes and hepatopancreas both decreased significantly at 6 h and 3 h respectively (P<0.05), then it increased to the highest and recovered to the control level at 72 h. The results indicated that pathogenic E. faecalis challenge affected the immune status of E. carinicauda probably by changing the immunity-related gene expression, and that proPO, CTL, SOD, Cat D and Cat L were all sensitive to E. faecalis infection.
