Study On Immunoregulation Effect Of Duck IFN-α Eukaryon Expression Plasmid To Ducks Immunized With DP Attenuated Vaccine

In the article, duck IFN-αeukaryon expression plasmid (pcDNA-SDIFN-α) was administrated to 28-day old ducks with the dose of 1,3,6μg per duck respectively by routes of Gene Gun Bombardment and the dose of 50,100,200μg per duck respectively by intramuscular injection(IM) and 15 days later, each duck was injected duck plague virus(DPV) attenuated vaccine. The control groups included empty vector, DPV attenuated vaccine and blank, anticoagulated blood samples were harvested at 3, 7, 14, 21, 28, 35, 49, 63, 84, 105 days to to detect the proliferation of ducks T lymphocytes in peripheral blood(PBL) by T lymphocyte proliferation tests (MTT); anticoagulated blood samples were harvested at 7, 14, 21, 28, 35, 49 days to detect the number of CD₃⁺ T lymphocytes of ducks by fluorescence activated cell sorter (FACS); and cruor samples harvested at 7, 14, 21, 28, 35, 49, 63, 84, 105, 126, 154, 182 days to detect anti-DPV antibody by indirect ELISA methods; and anticoagulated blood samples were harvested at 12h, 24h, 7d, 14d, 21d, 28d, 35d, 49d, 63d, 84d to detect the contents in blood by TaqMan-MGB real-time PCR.1. The reaction of T lymphocyts to ConA (OD value): After pcDNA-SDIFN-αwas administrated to ducks with different dosages via different routes, DPV attenuated vaccine was immunized, at the 3 days, The reaction of T lymphocyts to ConA was obviously higher than DPV, empty vector and blank control group, and achieved peak value at 28 days. Experiment groups were significantly different (P≤0.01) or different (P≤0.05) from DPV, empty vector and blank control group; DPV and empty vector control groups were different (P≤0.05) from the blank control group; The group of empty vector was higher than the group of DPV, but no difference was found (P≥0.05).2. Number of CD₃⁺ T lymphocyte: At 7 days, the number of CD₃⁺ T lymphocyte obviously increased in duck peripheral blood, the number of the groups immunized via Gene Gun Bombardment achieved peak value at 35 days, and achieved peak value at 28 days of the groups immunized via IM. Experiment groups were significantly different (P≤0.01) or different (P≤0.05) from DPV, empty vector and blank control group; DPV and empty vector control groups were significantly different (P≤0.01) or different (P≤0.05) from the blank control group; The group of empty vector was higher than the group of DPV, but no difference was found (P≥0.05).3. The level of antibody IgG in PBL(OD): At 7 days, the titres of IgG of all the groups (except blank control group) advanced fastly, and achieved peak value at 28 days. The groups of 1, 3, 6, 200μg groups were significantly different (P≤0.01) or different (P≤0.05) from blank control group, DPV and empty vector control group; The groups of 50,100μg were higher than the groups of DPV and empty vector, but no difference were found (P≥0.05); Between the group of empty vector and DPV had no difference (P≥0.05), but they were signifycantly different (P≤0.01) or different (P≤0.05) from the blank control group;4. Neutralizing antibody titer in PBL: All the ducks (except blank control ducks) produced specific IgG, the neutralizating antibody against DPV achieved peak value at 28 days. The group of 1, 3, 6, 200μg was higher than the group of 50, 100μg groups, DPV and empty vector control group.5. The contents of DPV-DNA in PBL: The DPV-DNA could be dectected at 12h in all the ducks (except blank control ducks), the copy numbers of DPV-DNA were signifycantly different (P≤0.01) from blank control group from 12 hour to 49 days, were about 3.5-4.2, and Amone experiment groups, empty vector and DPV control groups had no difference (P≥0.05).The results demonstrated that pcDNA-SDIFN-αadministrated 15 days befor injected DPV attenuated vaccine could enhance the ability of T lymphocytes proliferation, increase the number of CD₃⁺ T lymphocyte, enhance the titre of antibody IgG and neutralizing antibody in PBL, pcDNA-SDIFN-αcould significantly enhance the duck cell immunity, humoral immunity induced by DPV attenuated Vaccine, is an excellent DPV attenuated Vaccine molecular adjuvant, the best result could be obtained with the dosage of 200μg per duck of pcDNA-SDIFN-αadministrated via IM and 1μg per duck administrated via Gene Gun Bombardment. Different dosage of pcDNA-SDIFN-αhas no influence to propagation of DPV in duck PBL administrated via different routes. In the cell immunity side pcDNA- SDIFN-αadministrated via Gene Gun Bombardment have an advantage of via IM, in the humoral immunity side pcDNA-SDIFN-αadministrated via IM have an advantage of via Gene Gun Bombardment.