Construction and characterization of invasion protein B gene deleted mutant asd host-vector balanced lethal system / 中国免疫学杂志

Objective: To develop an oral live vaccine vector which stably carries exogenous genes.Methods:SL1344ΔsipBΔasd host-vector balanced lethal system was constructed by the method of recombinant suicide plasmid-mediated allelic exchange on the basis of attenuated Salmonella typhinurium SL1344ΔsipB.Then,the biological characteristics of SL1344ΔsipBΔasd was analyzed.Results:The results showed that the mutant was stabile with the Δasd gene in vitro;the serotype and growth rate of SL1344ΔsipBΔasd strain was almost same as the parent SL1344ΔsipB and SL1344 strain.And the mutant strains remain swim ming zones.Virulence test in mice showed that the virulence of SL1344ΔsipBΔasd which carried complementary plasmid pYA3493 by electro-transformation decreased by 1.4%compared with SL1344.Conclusion: These results showed that the SL1344ΔsipBΔasd mutant was successfully constructed.It is likely that this mutant should be used as a live vector to express foreign genes.

Construction and characterization of host-vector balanced lethal system of attenuated salmonella choleraesuisΔcrpΔcyaΔasdC78-1 (pYA3493) / 中国免疫学杂志

Objective:In order to develop an oral live vaccine vector of swine that can stably carry exogenous genes.Methods:Mutant ΔcrpΔcyaΔasdC78-1 was constructed by the method of suicide plasmid pREasd-mediated bacteria homologous recombination on the basis of attenuated Salmonella choleraesuisΔcrpΔcyaC78-1.Complementary plasmid pYA3493 with asd was electrotransformed into the mutant,and thenΔcrpΔcyaΔasdC78-1(pYA3493) host-vector balanced lethal system was constructed.Its biological characteristics were analyzed further.Results:The results of PCR and sequencing showed thatΔcrpΔcyaΔasdC78-1(pYA3493) was constructed suc-cessfully.Biological characteristics showed that the serotype of ΔcrpΔcyaΔasdC78-1(pYA3493) was identical to ΔcyaΔasdC78-1 and vaccine strain C500 and it can stably carry theΔasd gene in vitro;its growth speed was a little slower than ΔcrpΔcyaC78-1 strain,but both of their growth speeds were significantly slower than vaccine strain C500;the biochemical characteristics of ΔcrpΔcyaΔasdC78-1 ( pYA3493 ) were basically the same with ΔcrpΔcyaC78-1 strain.Oral virulence test in mice showed that the virulence ofΔcrpΔcyaΔasdC78-1 ( pYA3493 ) was similar with ΔcrpΔcyaC78-1, but its median lethal dose is 412 times of vaccine strain C500.Conclusion:These results demonstrated that attenuated Salmonella choleraesuisΔcrpΔcyaΔasdC78-1(pYA3493) strain had the potential to be used as an oral live vaccine vector for expressing foreign genes efficiently.