The Roles of β-Integrin of Chinese Shrimp (Fenneropenaeus chinensis) in WSSV Infection

Our previous study demonstrated that an integrin beta subunit of Chinese shrimp (Fenneropenaeus chinensis) (Fc beta Int) plays an important role in white spot syndrome virus (WSSV) infection. In the present work, in order to further elucidate the potential role of Fc beta Int in WSSV infection, the recombinant extracellular domain of beta integringene of F. Chinensis (rFc beta Int-ER) was expressed in Escherichia coli BL21 (DE3), and the eukaryotic expression plasmid PcDNA3.1-Fc beta Int-ER (PFc beta Int-ER) was also constructed. Far-western blotting was performed to determine the binding specificity of rFc beta Int-ER to WSSV envelope proteins, and results showed that rFc beta Int-ER was able to specifically interact with rVP31, rVP37, rVP110 and rVP187. Moreover, the blocking effects of mouse anti-rFc beta int-ER antibodies were both detected in vivo and in vitro. The ELISA and Dot-blotting in vitro assays both showed that mouse anti-rFc beta Int-ER antibodies could partially block the binding of WSSV to the hemocyte membrane of F. chinensis. In the in vivo assays, the mortality of shrimp injected with WSSV mixed with anti-rFc beta Int-ER antibodies was delayed, and was lower than in the control group. While the shrimp were intramuscularly injected with PFc beta Int-ER, transcripts of PFc beta Int-ER could be detected in different shrimp tissues within 7 days, and the mortality of shrimp injected with PFc beta Int-ER was also delayed and lower compared with the control group post WSSV challenge. Furthermore, gene silencing technology was also used to verify the effect of Fc beta Int in WSSV infection, and results showed that the expression levels of the WSSV immediate early gene iel, early gene wsv477, and late gene VP28 and the mortality of F. Chinensis were all significantly decreased in the Fc beta Int knock-down hemocyctes compared to the control group. Taken together, these results suggest that Fc beta Int plays important roles in WSSV infection.