Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10971987 | Fish & Shellfish Immunology | 2014 | 8 Pages |
Abstract
Attenuated Salmonella typhimurium SL7207 was used as a carrier for a reconstructed DNA vaccine against Streptococcus agalactiae. A 1.02 kb DNA fragment, encoding for a portion of the surface immunogenic protein (Sip) of S. agalactiae was inserted into pVAX1. The recombinant plasmid pVAX1-sip was transfected in EPC cells to detect the transient expression by an indirect immunofluorescence assay, together with Western blot analysis. The pVAX1-sip was transformed by electroporation into SL7207. The stability of pVAX1-sip into Salmonella was over 90% after 50 generations with antibiotic selection in vitro while remained stable over 80% during 35 generations under antibiotic-free conditions. The LD50 of SL/pVAX1-sip was 1.7 Ã 1011 CFU/fish by intragastric administration which indicated a quite low virulence. Tilapias were inoculated orally at 108 CFU/fish, the recombinant bacteria were found present in intestinal tract, spleens and livers and eventually eliminated from the tissues 4 weeks after immunization. Fish immunized at 107, 108 and 109 CFU/fish with different immunization times caused various levels of serum antibody and an effective protection against lethal challenge with the wild-type strain S. agalactiae. Integration studies showed that the pVAX1-sip did not integrate with tilapia chromosomes. The DNA vaccine SL/pVAX1-sip was proved to be safe and effective in protecting tilapias against S. agalactiae infection.
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Authors
L.Y. Huang, K.Y. Wang, D. Xiao, D.F. Chen, Y. Geng, J. Wang, Y. He, E.L. Wang, J.L. Huang, G.Y. Xiao,