Interaction between Sea perch iridovirus (SPIV) infection and gut microbes in sea perch Lateolabrax japonicus

Sea perch iridovirus (SPIV) infection causes severe disease of fish and has led to economic loss of the sea perch Lateolabrax japonicus aquaculture industry. In this study, severe pathological damage of SPIV-infected sea perch was observed; the relationship of SPIV infection, gut microbial community structure, and gut transcripts of sea perch were explored. SPIV infection could inhibit normal immune function of the gut. The expression levels of immune genes such as MHC I, MHC II, TCR, BCR, and IgM were down-regulated during SPIV infection. Intestinal immunosuppression breaks the balance between mucosal immunity and gut microbes. Opportunistic pathogens such as Lawsonella, Corynebacterium, and Achromobacter expanded substantially following SPIV infection. The abundance of potential probiotics in aquatic animals such as Romboutsia declined following SPIV infection. Intestinal microbial lipopolysaccharide biosynthesis and bacterial secretion related functions increased in SPIV infection and correlated with the expression of intestinal lipopolysaccharide binding protein (LBP), TLR5, IL-1 beta and other genes. These results suggest that gut microbes can stimulate the innate immune system and trigger an acute inflammatory response through LPS. In conclusion, we analyzed the interaction between SPIV infection and gut microbes and provided a basis for further studies on the mechanism of SPIV pathogenesis and treatment.