An integrin β subunit of Chinese shrimp Fenneropenaeus chinensis involved in WSSV infection

An integrin β subunit (FcβInt) cDNA was cloned from hemocytes of Fenneropenaeus chinensis by rapid amplification of cDNA ends (RACE) PCR. The full-length cDNA of FcβInt consists of 2853 bp and encodes a polypeptide of 783 amino acids with a predicted isoelectric point of 5.09. The deduced amino acid sequence of FcβInt possessed the classical domains of β integrin, including the βA domain and four epidermal-growth-factor (EGF)-like domains, which shared highest similarity with a β integrin of Pacifastacus leniusculus. The FcβInt mRNA was highly expressed in hemocytes, heart and gill, and moderately in gonad and intestine, whereas low expression level was found in muscle and hepatopancreas. FcβInt mRNA in gill was significantly up-regulated in 24 h and then gradually decreased below the control level in response to WSSV challenge. The cDNA fragment encoding the extracellular region of FcβInt (FcβInt-ER) was expressed in Escherichia coli BL21 (DE3), and polyclonal antibodies against recombinant FcβInt-ER (rFcβInt-ER) were produced, which could specifically react to the hemocyte membrane by immunofluorescence assay and recognize a 120 kDa protein in the hemocytes by western blotting. By ELISA and dot-blot binding assay, rFcβInt-ER exhibited specific WSSV binding activity. Neutralization assay in vivo further demonstrated that rFcβInt-ER could partially block WSSV infection to shrimp. These results suggested that FcβInt plays an important role in WSSV infection.

► A full length β-integrin cDNA was cloned from hemocytes of Chinese shrimp.
► β-integrin mRNA was significantly up-regulated against WSSV infection.
► A 120 kDa putative native integrin β subunit was identified in hemocytes.
► Recombinant extracellular region of β-integrin exhibited WSSV binding activity.
► rFcβInt-ER could partially block WSSV infection by neutralization assay in vivo.