Cell-culture derived fowl adenovirus serotype 4 inactivated vaccine provides complete protection for virus infection on SPF chickens

Abstract

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.

Keywords: Fowl adenovirus serotype 4; Hydropericardium–hepatitis syndrome (HHS); Inactivated vaccine; Inclusion body hepatitis (IBH); LMH cells.

Fig. 1

Antibody response of vaccinated chicken measured by commercial FAdV ELISA kit. Results were indicated as the sample to positive (S/P) ratio of the OD values; S/P ratios ≥0.5 were considered positive. Asterisks (*) marks significant differences between groups (p < 0.05, n = 10). The error bars indicate standard deviation

Fig. 2

Gross lesions in liver and heart from chicken challenged with FAV-HN strain. The solid arrow indicates hepatitis. The solid triangles indicate hydropericardium. a Liver and heart tissues of unchallenged control chicken. b Liver and heart tissues from the challenged control chicken showing intranuclear inclusions. c Liver and heart tissues of challenged chicken immunized with cell-culture derived inactivated vaccine. d Liver and heart tissues of challenged chicken immunized with embryo-adapted inactivated vaccine

Fig. 3

Histological changes in liver of chicken challenged with FAV-HN strain. The solid arrows indicate viral inclusion bodies in liver cells. The solid triangles indicate hepatocyte steatosis. a Liver sections of unchallenged control chicken. b Liver sections of challenged control chicken. c Liver sections of challenged chicken immunized with cell-culture derived inactivated vaccine. d Liver sections of challenged chicken immunized with embryo-adapted inactivated vaccine