Potential role of single hotdog fold thioesterase in the antiviral response of Fenneropenaeus chinensis

Thioesterase superfamily member 2 (Them2) is a single hotdog fold thioesterase domain–containing protein. Its biological function is not well known. Recently, a hotdog fold thioesterase (FcThem) was cloned for the first time from the Chinese white shrimp. The full length of FcThem is 748 bp. It encodes a protein with 142 amino acids with a predicted molecular mass of 14.79 kDa and an isoelectric point of 8.76. No signal peptide was predicted. Multiple alignment of FcThem with other Them2 proteins suggested a conserved HGG motif. Phylogenetic analysis showed that FcThem were clustered with vertebrate Them2 protein into one group. The RT-PCR results showed that FcThem was a widely distributed gene and could be detected in the hemocytes, heart, hepatopancreas, gills, stomach, intestines, and ovaries of unchallenged shrimps. In hemocytes, its transcript was upregulated 24 h post WSSV challenge. In the gills, the FcThem went up at a 6 h WSSV challenge. FcThem expression in the ovaries was also affected by the WSSV and was increased after the 2 h WSSV challenge, reaching the highest level at 6 h. Our results show that FcThem probably has roles in the innate immunity system of shrimps and investigations will be carried out to explore this finding further.