| Avian colibacillosis normally experiences pericarditis,perihepatitis,air sacculitis and other clinic diseases,leading to the problems of high mortality rate,low hatchability and so on.This study focused on the storage and efficacy of Montanide TSA 71 VG trivalent inactivated vaccine(TIV)through three mutant strains derived from avian pathogenic Escherichia coli(APEC):E516ΔlpxLΔlpxM(01),E058ΔlpxLΔlpxM(02),E522ΔlpxLΔlpxM(078).The results of the study showed as following:1.The storage period of avian colibacillosis trivalent inactivated vaccine with an adjuvant Montanide TSA 71 VGThe storage period was to evaluate the inactivated vaccine E516 Δ lpxL Δ lpxM(O1)、E058△lpxL Δ lpxM(02)、E522 △ lpxZ Δ lpxM(078)with an adjuvant Montanide TSA 71 VG which prepared in the laboratory,to explore its safety and immune potency on the 9th month and 12th month post-storage,respectively.The immunized birds were observed for 7 days post-vaccination with vaccine stored for 9 months and 12 months,respectively.The results showed only birds injected with 1 ml/bird show decreased appetite,which recovered at 24 hours after vaccination.Lumps with the diameter of 0.1 cm-1.2 cm appeared at the site of injection,whiledisappeared after 1 week post-vaccination,and there was no significant difference on average daily gain(ADG)between vaccinated birds and mock birds,indicating that the vaccine was safe being stored for 9 months and 12 months at 2～8 ℃.In the vaccination-challenge trial,the specific pathogen free(SPF)chickens were immunized on 14 day-old and challenged on 35 day-old,and the serum of all birds was collected every week after vaccination.Indirect haemagglutination test(IHA)was used to determine the serum antibody elicited by the vaccine with a nine or twelve months storage.For IHA,chicken erythrocyte was sensitized by lipopolysaccharide(LPS)derived from APEC E058 strain of 02 serotype,E516 strain of 01 serotype and E522 of 078 serotype.Over 90.00%challenged chickens died in challenge-only group.Meanwhile,birds vaccinated with the 9-month-storage vaccine,the survive rate was 70.00%against E516 strain challenge,77.78%against E058 strain challenge and 88.89%against E522 strain challenge,respectively.Birds vaccinated with the 12-month-storage vaccine,their survive rate agianst E516,E058 and E522 strain challenge reached to 70.00%,77.78%and 88.90%respectively.These results showed that both the safety and the immune potency of the prototype avian colibacillosis trivalent inactivated vaccine were satisfied after storage for 9 to 12 months at 2～8 ℃.2.Passive immune potency of avian colibacillosis trivalent inactivated vaccinewith an adjuvant Montanide TSA 71 VGSPF hens with the age of 120 days were immunized with the a dose of 0.5 ml/bird.Serum of hens was collected at 0.5,1,2,3 month after immunization,respectively.At meanwhile,the breeding eggs from immunized hens were collected and hatched at the same time points,respectively.The new hatched chicks were sampled with serum,and challenged at 7-and 14-day-old,respectively.The result showed that IHA antibody titer of hens varied from 1:8 to 1:32 at 0.5 month post-vaccination;and reached to 1:32～1:128 during the 1～2 months after immunization;and finally reduced to 1:16～1:64 at the 3 month post-immunization.The collected breeding eggs from immunized hens at the 0.5 month post-vaccination,the IHA antibody titer of hatched chicks was between 1:2-1:16 at 7 day-old,and 0～1:8 at14 day-old.While in terms of the collected breeding eggs from immunized hens during I and 2 months post-vaccination,the IHA antibody titer of new hatched chicks was between 1:16～1:64 and 1:8～1:32 at 7-and 14-day-old,respectively.The new hatched chicks from the breeding eggs of immunized hens either 0.5 or 3 month were not totally protected from APEC challenge.The efficacy of 7-day-old chicks originated from immunized hens at 0.5 month post-vaccination was between 12.50%～14.30%after challenge;and the efficacy of 14-day-old chicks varied from 12.50%to 22.00%.As for the new hatched chicks from immunized hens at 3 month post-vaccination,the efficacy of 7-day-old and 14-day-old chicks were between 12.50%～22.00%and 37.50%～50.00%after challenge,respectively.The new hatched chicks from the breeding eggs of immunized hens during 1 to 2 months after immunization were totally protected from APEC challenge,and the IHA antibody titer in hens was between 1:32～1:128 in this period.The efficacy of new hatched chickens of 7-and 14-day-old after challenge was between 55.56%～88.89%and 60.00%～88.89%,respectively.It can be concluded that the maternal antibody level was directly related to the passive immune efficiency of new hatched chicks.All new hatched chickens of either 7-or 14-day-old originated from the immunized hens at the 0.5 or 3 month post-vaccination were not totally protected from challenge;while those from the immunized hens during 1～2 months post vaccination can be protected.Therefore,the passive immune offered by immunized hens is 1～2 months post vaccination.The new hatched chickens of 14-day-old from the immunized hens in effective passive immune duration were not be totally protected after challenge,so the primary vaccination of new hatched chicks should be at 14-day-old. |
