Preparation and Protective Efficacy of Inactivated Vaccine of Chicken Flavivirus

After serially passaged in specific pathogen free embryonated chicken eggs,the chicken flavivirus strain FQ-C1 was stable at a titer of 1 × 104. 33ELD 50 per 0. 1 mL after 40 passages. Inactivated with formaldehyde,the passaged virus of strain FQ-C1 emulsified with mineral oil adjuvant in an appropriate ratio, and then inactivated vaccine was made. We tested the biosecurity of the inactivated oil-emulsion vaccines through immunization in 1-day-old chicken and laying hens. The results showed that animals immunized with the inactivated vaccines appeared no adverse effects. Twenty-eight days after administration of inactivated vaccine with a dose of 1 mL per chicken,the laying hens attacked by a virulent chicken flavivirus. The results showed that the laying rate of hens immunized with vaccine was 75. 8% higher than that of control group,and the protective efficacy of the inactivated vaccine on egg production was no less than 93. 2%. All of the results indicated that the inactivated oil-emulsion vaccine had good immunogenicity,which could effectively resist egg-dropping caused by chicken flavivirus.