Generation of killed but metabolically active (KBMA) Edwardsiella tarda and evaluation of its potential as a protective vaccine. Issue 2 (August 2015)

• Record Type: Journal Article
• Authors: Choi, Seung Hyuk; Kim, Min Sun; Kim, Ki Hong
• Is Part Of: Fish & shellfish immunology. Volume 45:Issue 2(2015:Aug.)
• Page Start: 889
• Page End: 894
• Publication Date: 2015-08
• Subjects: Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2015.06.012
• Languages: English
• ISSNs: 1050-4648

Abstract

<abstract xml:lang="en" abstract-type="author" id="abs0010"> <title id="sectitle0010">Abstract</title> <sec> <p id="abspara0010">A technology for inactivation of pathogens in human blood products by treatment with amotosalen hydrochloride (S-59) in combination with long wavelength ultraviolet light (UVA) to decrease transfusion-mediated sepsis has been applied to make safe vaccines against human pathogenic bacteria, and the resultants were called killed but metabolically active (KBMA) bacteria. In the present study, we first generated KBMA <italic>Edwardsiella tarda</italic> and evaluated its potential as a protective vaccine in olive flounder (<italic>Paralichthys olivaceus</italic>). To prevent the restoration of division ability by removal of psoralen adducts in the bacterial chromosome through the nucleotide excision repair (NER), the <italic>uvrA</italic> and <italic>uvrB</italic> genes knock-out <italic>E. tarda</italic> (<italic>ΔuvrAB E. tarda</italic>) was produced by the allelic exchange method. The optimal condition for generation of KBMA <italic>E. tarda</italic> was exposure of the <italic>ΔuvrAB E. tarda</italic> to 100 ng/ml of S-59 and 2.8 J/cm<sup>2</sup> of UVA irradiation. The KBMA <italic>E. tarda</italic> could not replicate but showed a high metabolic activity (measured by lactate dehydrogenase activity) that was comparable to the wild-type <italic>E. tarda</italic>. In comparison of survival rates between groups vaccinated with the same dose of bacteria, fish immunized with KBMA <italic>E. tarda</italic> showed significantly higher survival rates than fish immunized with formalin-killed cell (FKC) <italic>E. tarda</italic>. Furthermore, fish immunized with 1 × 10<sup>7</sup> CFU/fish of KBMA <italic>E. tarda</italic> showed no mortality, while PBS-injected fish showed 100% mortality. The serum agglutination titer was sharply increased by 10<sup>7</sup> CFU/fish of KBMA <italic>E. tarda</italic> compared to those of fish immunized with 10<sup>6</sup> CFU/fish of KBMA <italic>E. tarda</italic> or 10<sup>7</sup> CFU/fish of FKC <italic>E. tarda</italic>. The consistently lower serum agglutination titers against KBMA <italic>E. tarda</italic> than against FKC <italic>E. tarda</italic> in both KBMA and FKC <italic>E. tarda</italic> immunized groups suggest that some factors secreted from KBMA <italic>E. tarda</italic> might inhibit the serum agglutination activity. In conclusion, the present results showed the higher potential of KBMA <italic>E. tarda</italic> than FKC <italic>E. tarda</italic> as a prophylactic vaccine.</p> </sec> </abstract>