The Immune Effects Of Nano-aluminum Adjuvanted Avian Influenza Vaccine (H₅N₁) In Chickens

Avian influenza is an kind of infectious disease caused by influenza virus type A adapted to birds. The disease,with a history of hundreds of years,has been bringing great losses.Since its first outbreak in Hong Kong in 1997,which led to death of humans infected with H₅N₁AIV,a large number of human deaths have been on record.At present,the effective way to prevent and control HPAI is to inject oil emulsion vaccine,which,however,turns out unsatisfactory.Firstly,it takes quite long to reach effective antibody titer after the first vaccine,which makes it difficult to achieve immune protection within a short time in emergency.Secondly,oil adjuvant,with strong stimulation, is difficult to absorb,and some is even remained in the body when the poultry are killed and sold. That will lay a great quality problem for those poultry products.Therefore,it's in urgent need to search an alternative of oil adjuvant to fill such a gap.In recent years,the development of nanotechnology has shed some light on this issue.With support of research projects in Chongqing, our group studied the preparation of nano-aluminum,the ratio of nano-aluminum and avian flu antigen as well as the best absorption rate,the safety of nano-aluminum vaccine,its immune effects and mechanism.In this paper the immune effects of self-made nano-aluminum adjuvant vaccine of avian influenza(H₅N₁) are observed in chickens.Animal group and treatment:Breed 500 one-day-old Rongchang chickens with green feet by routine method for 10 days.Then, detect their maternal antibody,and divide the 240 chickens,whose maternal antibody was kept at a level of log2,into 4 groups by the principle of consistency of maternal antibodies.On Day 14,each chicken was injected with a does of 0.5ml immune medicine.Groupâ… was inoculated with nano-aluminum adjuvanted avian influenza H5N1 inactivated vaccine,Groupâ…¡with oil- adjuvant H₅N₁ vaccine,Groupâ…¢with conventional aluminum adjuvant of avian influenza H5N1 inactivated vaccine,and Groupâ…£injected with sterile normal saline.Blood samples of 10 chickens selected from each group were randomly collected on Day 17,19,21,24,28,35 and 49.Their serum antibodies were detected.On Day 21,35 and 49,five chickens were selected from each group respectively.Weigh them before determinating the rate of Lymphocyte rosette formation, lymphocyte proliferation activity,contents of LSZ in blood serum and cytophagic index of macrophage.Check the site of vaccine injection after killing them,and separate the thymus,spleen, bursa and the injected muscle,and carry out routine paraffin sections.Experimental results:1 Study on specific immune effects of nano-aluminum avian influenza vaccine(H₅N₁) in chickensNano-group can soon stimulate immune response.Their effective antibody was produced three days earlier than that in oil-group,and seven days earlier than in the conventional aluminum group. And the time to reach the highest concentration of antibodies was also advanced by 14 days, compared to the latter two groups,but the duration of antibody not as long as that in oil-group.On Day 21,the rate of Lymphocyte rosette formation and lymphocyte proliferation activity in nano-Group were slightly higher than those of the other three groups,however,all groups showed no significant difference(P＞0.05).2 Study on non-specific immune effects of nano-aluminum avian influenza vaccine(H₅N₁) in chickensOn Day 21,the contents of LSZ in blood serum and cytophagic index of macrophage in nanogroup were significantly higher than the oil-group and control group(P＜0.05);But on Day 35 and 49,the difference between the groups was not significant(P＞0.05).3 Study on effects of nano-aluminum avian influenza vaccine(H₅N₁) on chicken's immune organsOn Day 21,the index of thymicin in nano-group was significantly higher than the control group (P＜0.05),and the bursal index was significantly higher than the other three groups(P＜0.05). Histological observation indicated that the area of thymic lobule,thymic Cortex,splenic follicle and Lymph Follicles in Bursa of Fabricius in nano-group were also larger than the other three groups on Day 21.4 Study on chickens' response for nano-aluminum avian influenza H₅N₁ vaccineObservation of the injection sites indicated there was milky vaccine residue left not absorbed in oil-group on Day 35,while the vaccine was well absorbed in nano-group,only with a little light-yellow residue left on Day 21;the absorption of vaccine in the conventional aluminum group lagged slightly behind nano-group.H.E staining of the muscular biopsy found the inflammatory foci reduced gradually in nano-group on Day 35,while the oil-group and conventional aluminum group still have very strong inflammatory cell infiltration.On Day 49,inflammatory cells have been almost completely absorbed in nano-group,only with a few inflammatory cells left around the capillaries; inflammatory cells also decreased greatly in the conventional aluminum group,while a large number of inflammatory cells were not absorbed yet in oil-group.These results show that the nano-aluminum hydroxide,as HPAI H₅N₁ immune adjuvant,can enhance the immunity of chickens;compared with oil-adjuvant,it can also reduce the side effects of adjuvant,improve carcass quality of chickens,and provide a basis to further promote the application of nano-aluminum hydroxide adjuvant.