Generation of Biotechnology-DerivedFlavobacterium columnareGhosts by PhiX174 GeneE-Mediated Inactivation and the Potential as Vaccine Candidates against Infection in Grass Carp

Wenxing Zhu,Yuyu Zhang,Liguo An,Guiwen Yang,Jinduo Yuan

doi:10.1155/2012/760730

Wenxing Zhu, Yuyu Zhang + Show 3 more

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https://doi.org/10.1155/2012/760730

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Abstract

Flavobacterium columnare is a bacterial pathogen causing high mortality rates for many freshwater fish species. Fish vaccination with a safe and effective vaccine is a potential approach for prevention and control of fish disease. Here, in order to produce bacterial ghost vaccine, a specific Flavobacterium lysis plasmid pBV-E-cat was constructed by cloning PhiX174 lysis gene E and the cat gene with the promoter of F. columnare into the prokaryotic expression vector pBV220. The plasmid was successfully electroporated into the strain F. columnare G4cpN22 after curing of its endogenous plasmid. F. columnare G4cpN22 ghosts (FCGs) were generated for the first time by gene E-mediated lysis, and the vaccine potential of FCG was investigated in grass carp (Ctenopharyngodon idellus) by intraperitoneal route. Fish immunized with FCG showed significantly higher serum agglutination titers and bactericidal activity than fish immunized with FKC or PBS. Most importantly, after challenge with the parent strain G4, the relative percent survival (RPS) of fish in FCG group (70.9%) was significantly higher than FKC group (41.9%). These results showed that FCG could confer immune protection against F. columnare infection. As a nonliving whole cell envelope preparation, FCG may provide an ideal alternative to pathogen-based vaccines against columnaris in aquaculture.

Highlights

Flavobacterium columnare, a Gram-negative-gliding bacterium, is the causative agent of columnaris disease, one of the most important bacterial diseases of freshwater fish species [1]
F. columnare ghosts were generated for the first time by the controlled expression of the lysis gene E
Gene E-mediated lysis of bacteria resulting in empty cell envelopes is suggested as an alternative approach for the inactivation of bacteria without chemical or physical stress, which have frequently caused the reduction of antigenicity [8,9,10]

Summary

Introduction

Flavobacterium columnare, a Gram-negative-gliding bacterium, is the causative agent of columnaris disease, one of the most important bacterial diseases of freshwater fish species [1]. This bacterium is ubiquitous in aquatic environments, affecting wild and cultured fish as well as ornamental fish in aquaria [2]. Vaccination has become an increasingly important prevention strategy against infectious agents in farmed fishes [7]. A modified live columnaris vaccine has been developed and commercialized in the United States [11], and it is efficacious for prevention of columnaris disease in channel catfish and largemouth bass fry [12, 13].

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