Oral delivery of bacteria expressing wsv108 gene-specific dsRNA protects shrimp from white spot syndrome virus (WSSV) infection.

Double-stranded RNA (dsRNA) can specifically inhibit gene expression by RNA interference and has important application potential in animal disease control. White spot syndrome virus (WSSV) is one of the most harmful pathogens in shrimp aquaculture, causing huge economic losses every year. In this study, we investigated the function of the WSSV-encoded wsv108 protein. We demonstrated that wsv108 could promote apoptosis by interacting with heat shock protein 70 (HSP70) and enhancing the expression of multiple apoptosis-related genes. Silencing of wsv108 gene by injection with specific dsRNA prepared by in vitro transcription significantly increased the survival rate of WSSV-infected shrimp and reduced the viral load in tissues, suggesting that wsv108 is important for WSSV pathogenicity. Based on this, we expressed the wsv108 specific dsRNA in engineered Escherichia coli. Oral feeding of this bacterium could inhibit the expression of wsv108, increase the survival rate of WSSV-infected shrimp, and decrease the viral load of WSSV in tissues. Therefore, this study developed a new method for treatment of WSSV disease by oral administration of bacterially expressed dsRNA against a novel therapeutic target molecule, which could be a potential candidate strategy for WSSV control in aquaculture.

Basigin binds bacteria and activates Dorsal signaling to promote antibacterial defense in Penaeus vannamei.

The NF-κB pathway plays an important role in immune regulation. Basigin, an immunoglobulin superfamily membrane protein, is involved in the activation of NF-κB. However, its role in NF-κB signaling in response to pathogen infection remains unclear. In this study, we identified the Basigin gene from Pacific white shrimp, Penaeus vannamei, a representative species for studying the innate immune system of invertebrates. Basigin promoted the degradation of the IκB homolog Cactus, facilitated the nuclear translocation of the NF-κB family member Dorsal, and positively regulated the expression of Dorsal pathway downstream antimicrobial peptide genes. Interestingly, recombinant Basigin protein could bind a variety of Gram-positive and Gram-negative bacteria. Silencing of Basigin inhibited the Dorsal signaling activated by V. parahaemolyticus infection and significantly decreased the survival rate of V. parahaemolyticus-infected shrimp. The expression levels of the antimicrobial peptides ALF1 and ALF2 were downregulated, and the phagocytosis of hemocytes was attenuated in Basigin-silenced shrimp. Similar results were observed in shrimp treated with a recombinant extracellular region of the Basigin protein that was able to compete with endogenous Basigin. Therefore, to the best of our knowledge, this study is the first to demonstrate the function of Basigin as a pathogen recognition receptor that activates NF-κB signaling for antibacterial immunity in shrimp.