Construction of host-vector balanced lethal system of Salmonella typhimurium SL1344Δcya mutant and immune protection test of chickling

Abstract:

Abstract:［Objective］ To develop a host-vector balanced lethal system of Salmonella typhimurium adenylate cyclase mutant，and detect its biological characteristics.［Methods］ We constructed SL1344ΔcyaΔasd mutant strain by recombinant suicide plasmid ( pＲEΔasd)，and screened by two-step method，transformed pYA3493 plasmid containing the asd gene without resistance electric into the lack of SL1344 ΔcyaΔasd，then the recombinant strains SL1344 ΔcyaΔasd (pYA3493) was constructed successfully.［Results］The biochemical characteristics and growth rate of the mutant were different from that of the wild strain SL1344，but almost the same as that of the parent strain SL1344Δcya. The mutant strain could neither ferment maltose，lactose，and sorbitol，nor decompose H2 S，galactose and rat lee sugar，but still retained the ability to use glucose． The one-day chicken lethal test showed that SL1344ΔcyaΔasd (pYA3493) mutant was at least 104 times lower than SL1344 strain． The protection rate induced by the SL1344ΔcyaΔasd ( pYA3493) mutant was 62.5%.［Conclusion］The SL1344ΔcyaΔasd (pYA3493) mutant was successfully constructed，and had good immune protection，it laid a foundation for developing potential oral vaccines.