Involvement of tetraspanin 8 in the innate immune response of the giant prawn, Macrobrachium rosenbergii.

The tetraspanins, representing a conserved superfamily of four-span membrane proteins, are highly involved in viral and bacterial infections. Thus far, the function of the tetraspanins in crustaceans remains largely unknown. In this study, we report the cloning and expression analysis of a tetraspanin 8 from the giant freshwater prawn, Macrobrachium rosenbergii (named as MrTspan8). MrTspan8 contains a 720-bp open reading frame encoding a 239-amino acids protein, which exhibits four transmembrane domains and two extracellular loops that are typical for tetraspanins. MrTspan8 was found to be widely expressed in a variety of prawn tissues including heart, gill, muscle, gut, and hepatopancreas. Additionally, MrTspan8 expression was significantly increased in the hepatopancreas and gill of the prawns challenged by the bacterial pathogen Aeromonas hydrophila. Moreover, we show that pre-incubation of the peptides from the large extracellular loop of MrTSPAN8 protein reduced the cell death caused by A. hydrophila infection in prawn tissue, suggesting that MrTSPAN8 could be a mediator for bacterial infection to prawn.