Baculovirus-expressed FAdV-4 penton base protein protects chicken against hepatitis-hydropericardium syndrome

Hepatitis-hydropericardium syndrome (HHS) is an infectious disease caused by fowl adenovirus serotype 4 (FAdV-4). Several structural and non-structural proteins of FAdV-4 have been expressed in Escherichia coli and baculovirus expression system to develop candidate subunit vaccines. However, the protective efficiency of baculovirus-expressed penton base protein has not been assessed. In this study, two recombinant capsid proteins, penton base and fiber-2, were constructed. And then, penton base and fiber-2 were administrated alone or together to specific pathogen-free (SPF) chickens at 14 days of life and boosted at 28 days of life. At 42 days of life, the immunized groups and the control group were challenged with FAdV-4 virulent strain. Results show that inoculating penton base or penton base+fiber-2 provided 100% protection to the chickens. All groups vaccinated with the recombinant protein produced detectable antibodies and showed no apparent lesions. Thus, baculovirus-expressed penton base protein is a promising candidate subunit vaccine.