Immunological Effectiveness Of The Oil-emulsion Inactivated Vaccine Against Duck Flavivirus Virus

Duck flavivirus virus (DFV) is new virus, which with the main feature of eggproduction decreased, is an acute and highly contagious disease. Since the diseaseoccurred, it has brought the huge economic losses to the duck industry of our country. Inview of that DFV is a new disease, there is few vaccine research for it. In order toreduce the losses caused by the disease, this study isolated the duck flavivirus virus.And on this basis, according to the conventional method prepared a duck flavivirusvirus inactivated oil emulsion vaccine, through animal experiment detected theimmunization of the vaccine; finally, the vaccine used for field trial, determined theantibody level of it, and analysised the application effects. Research on duck flavivirusvirus vaccine has important significance. This research mainly content is divided intothe following three aspects:1、Isolation and identification of the virusIsolated and identified a strain of duck flavivirus virus from Henan areas,compared with duck flavivirus virus sequence which published in Genbank, thehomology of the virus’s gene sequence is above95%, and the gene sequence has beensubmitted to Genbank (JQ669731), which also for the next preparation of vaccine laid afoundation.2、Preparation of duck flavivirus virus inactivated oil emulsion vaccine andimmune effect analysisDuck flavivirus virus infection causes severe egg-drop syndrome in duck. In thisstudy, the inactivated oil emulsion vaccine was prepared by the conventional methodsfrom the duck flavivirus virus isolated in sick duck of egg-drop syndrome with the virustiter of10-2.25ELD50/0.2mL. Ducklings at10day old were divided into4groups (n=20)and immunized with the vaccine at the dosage of0.2,0.5and0.8mL per duckling forthe vaccinated groups via intramuscular injection, with a unvaccinated control groupand challenged at28days post immunization (PI). In addition, the antibody level was highly significant (p<0.01) in0.5mL group to control group within7to21days PI,detected using the ELISA method. The E rosette forming rate in0.5mL group(67.09±1.23%) was also highly significant (p<0.01) to the control group (51.86±1.14%)at28days PI. Moreover, the protection rates of the vaccine were80%in0.2mL groupand100%in0.5and0.8mL groups, respectively, whereas, all duckings shown clinicalsigns with3died in post challenge. In conclusion, the results indicated that theinactivated oil emulsion vaccine of duck flavivirus virus was able to efficiently inducethe humoral and cellular immunity against duck flavivirus virus infection.3、Duck flavivirus virus inactivated oil emulsion vaccine in the field trialThe purpose of this test was to study the affection of the oil emulsion vaccineagainst duck flavivirus virus in the practical application. Through respectivelyvaccinated ducklings and the laying Duck, then respectively in0,14,28,42d collectedthe serum samples, and detected the antibody level. The results showed, the vaccine canimprove the immune antibody level of duck body, compared with the control group withsignificant difference (p<0.01), and the antibody level of the laying Duck was morehigh than the ducklings. Therefore, the results show that the oil emulsion vaccineagainst duck flavivirus virus can significantly improve the immunity of the body, andlaid the foundation for the commercialization of vaccine.