Environmental rearing conditions are key determinants of changes in immune gene expression patterns in shrimp midgut

Abstract

The super-intensive BioFloc Technology (BFT) system has been highlighted as a promising eco-friendly alter-native to the traditional shrimp rearing systems. To gain insight into the impact of environmental rearingconditions on shrimp intestinal immunity, we assessed the expression profile of key immunological genes in themidgut ofLitopenaeus vannameishrimp reared in two contrasting culture systems: the indoor super-intensive BFTand the outdoor intensive Green-Water System (GWS). From the 30 analyzed genes, the expression levels of 25genes were higher in the midgut of shrimp reared in BFT than in GWS. The main functional categories re-presented in BFT-shrimp were the prophenoloxidase-activating system, immune signaling, antimicrobial pep-tides, and RNA interference pathway. Comparatively, only the RNAi pathway gene Dicer-1 (LvDcr1) was moreexpressed in animals from the GWS group. However, despite the differences in gene expression, the total midgutbacterial abundance was similar between the experimental groups. Altogether, our results suggest that themicrobial-rich environment offered by the BFT system can be acting as an immunostimulant by altering theimmune expression profile of the midgut. The gene expression level found in GWS animals could be related tothe chronic presence of the IMNV in the Brazilian Northeast. Knowing the effects of environmental stress factorson the intestinal immune defenses can provide an in-depth understanding of the relationship between cultivatedshrimp and the major pathogens affecting the shrimp industry.