Development On Inactivated Vaccine Against Duck Parvovirus Disease

Since November 2014,ducks reared in parts of China have developed diseases characterized by stunted growth of ducklings,atrophy of the upper and lower jaw,and tongue extension.According to its clinical characteristics,it was named duck short beak and dwarf syndrome（SBDS）.The laboratory determined that the pathogen responsible for SBDS is duck parvovirus disease through pathogen isolation and animal regression experiments.At present,there is no commercial vaccine for the prevention and control of the disease,which has caused great economic losses to the domestic duck industry.In view of this,the duck duck parvovirus epidemic strain was used to prepare an inactivated vaccine against duck parvovirus disease,and some useful explorations of the laboratory experiments were carried out around the development of new products.Fifteen 1 d Cherry Valley ducklings were randomly divided into three groups:Group1（oral group）,each oral 1 mL of viral allantoic fluid:Group 2（intramuscular injection group）each only intramuscular injection of 1 mL of virus allantoic fluid(EID50 10^-4.5/0.2mL)and group 3（control group）each duck was orally administered with 1 mL of physiological saline.Groups 1 to 2 were housed in the same animal house and the control group was housed in another animal house.After the duck parvovirus was infected,three groups of animals were weighed and measured for beak length on the 7th,14th,and 21st days.The data showed that the weight of the ducklings in the oral group was significantly lower than that of the control group.The intramuscular injection group was lower than the control group,but not significantly,it can be determined that the optimal route of infection is the oral route.In order to determine the biological characteristics of the virus,the SD duck parvovirus spread from the duck embryo to 40 generations.Animals were challenged with10,20,30,and 40 generations of virus,respectively.Data analysis showed that the body weight of infected F10 virus group and control group and duck body length were extremely significant.The ducklings infected with the F20?F30 virus group and the control group had significant differences in body weight and body length.There was no significant difference between the ducklings infected with the F40 virus group and the control group.Detoxification can be detected within 21 days after infection.In conclusion,the virus reached the 40th generation and the pathogenicity of the virus to animals was reduced.Specific attenuated vaccines need further study.The preserved duck parvovirus isolate was passaged through the duck embryo five times and the virus allantoic fluid was harvested.Centrifuge at 9000 r/min for 10 min.Take the supernatant and add double antibodies.The all processed allantoic fluid and Tween-80were prepared in proportion to the aqueous phase.The oil and aqueous phase were mixed in a ratio of 2:1 to prepare an oil emulsion inactivated vaccine.We also inspected the purity of the virus and the appearance,viscosity,stability,safety and shelf life of the vaccine.In order to evaluate the immune efficacy of the prepared inactivated vaccine,50 1-day-old ducklings were randomly divided into 5 groups,10 in each group,and 1 to 4 groups were immunized groups.The immunization doses were 100μL,250μL,500μL,and 1000μL,respectively.5 groups for the control group.Immunoprotection experiments were conducted 7 days after immunization to observe the clinical symptoms and detoxification of the experimental ducks.The results showed that the vaccine had a milky white appearance,a water-in-oil type,no foreign virus contamination,a viscosity that was in line with the standard,good stability,no adverse effects on animals,and could be stored at 4℃ for more than 1 years;20 tests for vaccine safety were conducted on the 1st Age-old ducklings were randomly divided into two groups,with 10 in each group.One group of injection finished vaccines was the vaccine group,and the other group was injected with white oil adjuvant as the control group.After the vaccine group was compared with the control group,the mental state was normal and no inflammation occurred at the injection site,which proved that the safety test passed;in the immunoprotection experiment,the cloacae anal swab detected some positive in the challenge group 3 d after the challenge,and 100μLto 1000μL of four groups.All the immunization results were negative.The challenge group was all positive after 5 days of challenge,while all of the 1?4 groups were negative.Twenty-one days after the challenge,the challenge group still tested positive.All the four groups tested negative.The above results show that the prepared duck parvovirus inactivated vaccine is safe,stable,and easy to store and transport,and ducklings can obtain strong protection after immunization.In this study,animals were vaccinated with different generations of viruses tdetermine the biological characteristics of the virus.In order to effectively prevent the spread of this disease,duck inactivated vaccine of duck parvovirus was prepared with the strain,the vaccine was safe and effective,It can provide protection for young ducklings at the age of susceptibility,providing a basis for the development of duck parvovirus vaccine.