Inclusion body hepatitis and hepatitis-hydropericardium syndrome caused by high-pathogenic fowl adenovirus serotype 4 has recently plagued Chinese poultry industry and caused huge economic losses since 2013. So far, there is no commercial vaccine available to control this disease. In this study, we reported the development of both embryo-adapted and cell-culture derived inactivated FAdV-4 vaccines and evaluated their efficacies in chicken. Compared to embryo-adapted vaccine, cell-culture derived vaccine induced significantly earlier and higher serological response measured by AGP and ELISA. After virus challenge, chicken immunized with cell-culture derived vaccine did not showed any gross and histopathological lesions, whereas inclusion body hepatitis was observed in the liver of chicken vaccinated with embryo-adapted vaccine. No mortality was observed in both the vaccinated groups. The above results suggested that cell-culture derived FAdV-4 inactivated vaccine could be a better vaccine candidate than embryo-adapted vaccine to control FADV-4 infections in China.

Background: Newcastle disease virus (NDV) genotype VII has become the dominant genotype in China. However, NDV genotype II was used to make current commercial NDV vaccines. The mismatch of genotypes between circulating and vaccine strains of viruses may compromise the efficacy of vaccines. Methods:In this study, a current circulating NDV was attenuated by mutations of multiple basic amino acid motif of fusion cleavage site 112 RRQKGF 117 based on reverse genetic techniques. The recombinant virus was prepared as an inactivated vaccine to test its efficacy and compared with a commercial LaSota NDV vaccine on SPF chickens.Results: All vaccinated chickens survived by the end of the study. By contrast, the unvaccinated chickens were all dead before 5 days post-challenge (DPC). Compared to commercial LaSota vaccine, the experimental inactivated vaccine elicited earlier and higher titer of HI antibodies and had reduced titer and duration of virus shedding after challenge. Conclusion:The experimental inactivated NDV vaccine may work as a promising vaccine candidate to control the disease.NDV genotype II strains [7]. The cross-protection of vaccines to genotype VII virus was seldom explored. In this study, we developed an inactivated NDV genotype VII vaccine based on reverse genetic techniques and compared its efficacy with commercial LaSota vaccine on SPF chickens. Material and methods VirusNDV strain PLK-N-06 was isolated from an outbreak of ND in chickens and identified as velogenic [intracerebral pathogenicity index (ICPI) = 1.79, mean death time (MDT) = 49 h]. Phylogenetic analysis results showed that it belongs to NDV genotype VIId. The virus was grown in 10-day-old embryonated SPF chicken eggs. Allantoic fluid was collected for use.