title: Protective immunity of grass carp induced by DNA vaccine encoding capsid protein gene (vp7) of grass carp reovirus using bacterial ghost as delivery vehicles.
abstract: Grass carp reovirus (GCRV) is one of the most pathogenic aquareovirus and can cause lethal hemorrhagic disease in grass carp (Ctenopharyngodon idella). However, management of GCRV infection remains a challenge. Therefore, it is necessary to find effective means for the control of its infection. The uses of bacterial ghost (BG, non-living bacteria) as carriers for DNA delivery have received considerable attentions in veterinary and human vaccines studies. Nevertheless, there is still no report about intramuscular administration of bacterial ghost-based DNA vaccines in fish. In the current study, a novel vaccine based on Escherichia coli DH5α bacterial ghost (DH5α-BG), delivering a major capsid protein gene (vp7) of grass carp reovirus encoded DNA vaccine was developed to enhance the efficacy of a vp7 DNA vaccine against GCRV in grass carp. The grass carp was injected intramuscularly by different treatments -i) naked pcDNA-vp7 (containing plasmid 1, 2.5 and 5 μg, respectively), ii) DH5α-BG/pcDNA-vp7 (containing plasmid 1, 2.5 and 5 μg, respectively) and iii) naked pcDNA, DH5α-BG or phosphate buffered saline. The immune responses and disease resistance of grass carp were assessed in different groups, and results indicated that the antibody levels, serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, acid phosphatase (ACP) activity and alkaline phosphatase (AKP) activity and immune-related genes were significantly enhanced in fish immunized with DH5α-BG/pcDNA-vp7 vaccine (DNA dose ranged from 2.5 to 5 μg). In addition, the relative percentage survival were significantly enhanced in fish immunized with DH5α-BG/pcDNA-vp7 vaccine and the relative percentage survival reached to 90% in DH5α-BG/pcDNA-vp7 group than that of naked pcDNA-vp7 (42.22%) at the highest DNA dose (5 μg) after 14 days of post infection. Moreover, the level of pcDNA-vp7 plasmid was higher in DH5α-BG/pcDNA-vp7 groups than naked pcDNA-vp7 groups in muscle and kidneys tissues after 21 days. Overall, those results suggested that DH5α bacterial ghost based DNA vaccine might be used as a promising vaccine for aquatic animals to fight against GCRV infection.
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Xinong Road 22nd, Yangling, Shaanxi 712100, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Hao
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Xinong Road 22nd, Yangling, Shaanxi 712100, China.
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Chen
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Xinong Road 22nd, Yangling, Shaanxi 712100, China.
authors.forename: Xiao-Zhou
authors.initials: XZ
authors.lastname: Qi
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Xinong Road 22nd, Yangling, Shaanxi 712100, China.
authors.forename: Xiao-Bo
authors.initials: XB
authors.lastname: Yu
authors.affiliation: College of Veterinary Medicine, Northwest A&F University, Xinong Road 22nd, Yangling, Shaanxi 712100, China.
authors.forename: En-Qi
authors.initials: EQ
authors.lastname: Du
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Xinong Road 22nd, Yangling, Shaanxi 712100, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Ling
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Xinong Road 22nd, Yangling, Shaanxi 712100, China. Electronic address: zhubin1227@126.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Xinong Road 22nd, Yangling, Shaanxi 712100, China. Electronic address: wanggaoxue@126.com.
authors.forename: Gao-Xue
authors.initials: GX
authors.lastname: Wang
mesh_terms: D000818:Animals; D036022:Capsid Proteins / Q000276:immunology*; D002347:Carps; D005393:Fish Diseases / Q000276:immunology* / Q000821:virology; D007114:Immunization / Q000662:veterinary; D011897:Random Allocation; D012087:Reoviridae / Q000276:immunology*; D012088:Reoviridae Infections / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D019444:Vaccines, DNA / Q000276:immunology*; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D036022:Capsid Proteins; D019444:Vaccines, DNA; D014765:Viral Vaccines
keywords: Bacterial ghost; Grass carp; Grass carp reovirus; Innate immunity; Vaccine