Comparative immune efficacy of recombinant penton base and fibre proteins against fowl adenovirus - 2/11 infection in chickens

Abstract

Fowl adenovirus (FAdV) has 12 serotypes. However, recently hybrid types have also been reported. FAdV2/11 has emerged as the most frequently isolated FAdV type from Inclusion Body Hepatitis (IBH) and Hepatitis– Hydropericardium Syndrome (HHS) cases in chickens, causing severe economic impact worldwide. In an attempt to develop a subunit vaccine against FAdV-2/11 infection, viral capsid proteins, penton base and fibre, were expressed in E. coli and their immune potential was evaluated in domestic chicken. Purified recombinant proteins were administered on day 14 to specific pathogen-free (SPF) chickens followed by a challenge with the virulent virus on day 35 of life. The fibre induced the best immune response against the homologous challenge, with 80% protection. A moderate protective effect, resulting in 66% protection, was observed for penton base + fibre followed by the penton base vaccinated group manifesting 56% protection. Faecal excretion of the virus in immunized birds following the challenge was also studied. The study concludes that recombinant fibre protein may be a potential candidate for a subunit vaccine against FAdV-2/11 infection in chickens.