title: Asd-based balanced-lethal system in attenuated Edwardsiella tarda to express a heterologous antigen for a multivalent bacterial vaccine.
abstract: Edwardsiella tarda is an enteric Gram-negative invasive intracellular pathogen, which causes enteric septicemia in fish. It could be potentially used to develop a recombinant attenuated E. tarda vaccine for the aquaculture industry. Because live vaccine strains can potentially be released into the environment upon vaccination, medical and environmental safety issues must be considered. Deletion of the asdB gene in E. tarda resulted in a diaminopimelic acid (DAP)-dependent mutant. The wild type asdB gene was inserted in place of the antibiotic-resistance gene in the plasmid, and the resultant non-antibiotic resistant vector was transformed into the attenuated and DAP-dependent E. tarda vaccine strain (WEDΔasdB) to obtain a balanced-lethal system for heterologous antigen expression. The balanced-lethal expression system was further optimized by comparing plasmid replicons with different Shine-Dalgarno sequences and start codons for the asdB gene. Utilizing the optimized balanced-lethal expression system, the protective antigen gene gapA34 from the fish pathogen Aeromonas hydrophila LSA34 was expressed in the attenuated E. tarda to generate the multivalent vaccine candidate WEDΔasdB/pUTta4DGap. This vaccine was shown to evoke an effective immune response against both E. tarda and A. hydrophila LSA34 by vaccinating turbot via a simple immersion route. This multivalent E. tarda vector vaccine has great potential for broad applications in aquaculture.
authors: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Rd., Shanghai 200237, PR China.
authors: Yijian
authors: Y
authors: Yan
authors: Wei
authors: W
authors: Mu
authors: Lingzhi
authors: L
authors: Zhang
authors: Lingyu
authors: L
authors: Guan
authors: Qin
authors: Q
authors: Liu
authors: Yuanxing
authors: Y
authors: Zhang
mesh_terms: D016980:Aeromonas hydrophila / Q000235:genetics; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics*; D015478:Antigens, Heterophile / Q000235:genetics*; D017756:Aquaculture; D001428:Bacterial Vaccines / Q000276:immunology*; D020609:Edwardsiella tarda / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000472:pathogenicity; D004756:Enterobacteriaceae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary; D005393:Fish Diseases / Q000276:immunology / Q000517:prevention & control*; D005412:Flatfishes; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007274:Injections, Intraperitoneal / Q000662:veterinary; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000276:immunology; D012093:Replicon; D014613:Vaccines, Attenuated / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D015478:Antigens, Heterophile; D001428:Bacterial Vaccines; D011994:Recombinant Proteins; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; D049452:Green Fluorescent Proteins