Studies On Large-scale Production Of PcDNA-SDIFN-α Vaccine By Fermentation And PcDNA-SDIFN-α Inmmunized Ducks Against Challenge Infection Of Duck Plague Virus

Studies on the fermentation parameters of recombinant E.coli wich containts the plasmid pcDNA-SDIFN-αand pcDNA-SDIFN-αinmmunized ducks against challenge infection of 0.5 LD₅₀ duck plague virus, The results are as follows:1. The conditions of spionsad production of pcDNA-SDIFN-α: the fermentation parameters of recombinant E.coli wich containts the plasmid pcDNA-SDIFN-αwere investigated, the conditions of spionsad production was also investigated with DH5α, the optimal fermentation conditions were as follows: temperature 37℃, pH7.4, the content of oxygen 40%, speed of accretion 80ml/L, loading amount 4%, the content of defoamer 0.02% .The productivity of optimal fermentation condition reached 357mg/L.2. pcDNA-SDIFN-αinmmunized ducks against challenge infection of 0.5 LD₅₀ duck plague virus:Some BeiJing ducks were immunized once time with 1, 3, 6μg pcDNA-SDIFN-αDNA vaccine respectively by the route of gene gun, the others were immunized once time with 50, 100, 200μg pcDNA-SDIFN-αDNA vaccine respectively by the route of intramuscular injection, PBS, pcDNA3.1(+)and attenuated duck plague virus vaccine as control, challenged with duck plague virus(DPV) 0.5 LD₅₀ ( copies of virus: 3.524x10⁴) after immunization 15 days later, record the condition of morbidity and death. Collected the peripheral blood samples at 2h, 6h, 12h, 24h, 3d, 6d, 9d, 14d, 22d, 26d, 33d and 40d. The real-time fluorescence quantitative PCR was used to detect the number of DPV-DNA in blood. Results:â‘ The number of DPV-DNA in peripheral blood of ducks immunized by gene gun was significant different (P＜0.05) between pcDNA-SDIFN-αgroups and PBS groupand pcDNA 3.1(+) group. The number of DPV-DNA was not different between pcDNA-SDIFN-αgroups and duck plague virus vaccine group (P＜0.05). The number of DPV-DNA in peripheral blood was not different(P＞0.05) between 1μg, 3μg and 6μg group. The number of DPV-DNA of 6μg group was the least, 3μg group was more, 1μg group was the most in early days. 3/9 ducks infected subcutaneously with DPV and 3/9 ducks infected nasally with DPV of 1μg pcDNA-SDIFN-αgroup were dead, 3/9 ducks infected nasally with DPV of 3μg pcDNA-SDIFN-αgroup were dead, and 13/27 duck of PBS and 10/12 pcDNA 3.1(+) groups were dead, ducks of 6μg pcDNA- SDIFN-αgroup and attenuated DPV vaccine groups were all alive. The number of DPV-DNA of spleen, duodenum, jejunum, appendices and recta of dead ducks was more than other tissue.â‘¡The number of DPV-DNA in peripheral blood of ducks immunized by intramuscular injection was significant different(P＜0.05) between pcDNA-SDIFN-αgroups and PBS group and pcDNA 3.1(+) group. The number of DPV-DNA was not different(P＞0.05) between pcDNA-SDIFN-αgroups and duck plague virus vaccine group. The number of DPV-DNA of 200μg group was the least, 100μg group was more, 50μg group was the most in early days.All the ducks immunized pcDNA- SDIFN-αDNA by intramuscular injection were alive, but 13/27 duck of PBS and 10/12 pcDNA 3.1(+)groups were dead.Conclusion: pcDNA-SDIFN-αcan counteract the infection of DPV and some dose-dependent relationship.