Inv1: an Edwardsiella tarda invasin and a protective immunogen that is required for host infection |
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Authors: | Li Mo-fei Hu Yong-hua Zheng Wen-jiang Sun Bo-guang Wang Chun-lin Sun Li |
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Affiliation: | a Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China b Lanzhou Branch, National Science Library, Chinese Academy of Sciences, 8 Tianshui Middle Road, Lanzhou, Gansu, China c Graduate University of the Chinese Academy of Sciences, Beijing 100049, China d Ningbo University, 818 Fenghua Road, Ningbo 315211, China |
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Abstract: | Invasin is an outer membrane protein that is known to mediate entry of enteric bacteria into mammalian cells. In this study, we analyzed the function and immunoprotective potential of the invasin Inv1 from Edwardsiella tarda, a serious fish pathogen that can also infect humans. In silico analysis indicated that Inv1 possesses a conserved N-terminal DUF3442 domain and a C-terminal group 1 bacterial Ig-like domain. Subcellular localization analysis showed that Inv1 is exposed on cell surface and could be recognized by specific antibodies. Mutation of inv1 had no effect on bacterial growth but attenuates overall bacterial virulence and impaired the ability of E. tarda to attach and invade into host cells. Consistent with these observations, antibody blocking of Inv1 inhibited E. tarda infection of host cells. To examine the immunoprotective potential of Inv1, recombinant Inv1 (rInv1) corresponding to the DUF3442 domain was purified and used to vaccinate Japanese flounder (Paralichthys olivaceus). The results showed that rInv1 induced strong protection against lethal-dose challenge of E. tarda. ELISA analysis showed that rInv1-vaccinated fish produced specific serum antibodies that could enhance the serum bactericidal activity against E. tarda. Taken together, these results indicate that Inv1 is a surface-localized virulence factor that is involved in host infection and can induce effective immunoprotection when used as a subunit vaccine. |
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Keywords: | Invasin Edwardsiella tarda Virulence Vaccine |
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