Recombinant fiber-1 protein of fowl adenovirus serotype 4 induces high levels of neutralizing antibodies in immunized chickens

Abstract

Virulent fowl adenovirus serotype 4 (FAdV-4) causes hydropericardium syndrome (HPS) with high mortality in chickens, leading to significant economic losses to the poultry industry. The development of an effective vaccine is essential for successful disease control. Here, we produced recombinant fiber-1 protein of FAdV-4, isolated from a Japanese HPS outbreak strain, JP/LVP-1/96, using a baculovirus expression system and evaluated its immunogenicity and protective efficacy. Recombinant fiber-1 protein induced high levels of neutralizing antibodies in immunized chickens, which were maintained for a minimum of 10 weeks. After being challenged with the virulent FAdV-4 strain JP/LVP-1/96, the immunized chickens did not exhibit clinical signs of infection or histopathological changes, there was a significant reduction in the viral load in various organs and total serum proteins, and albumin levels did not decline. These results suggest that the recombinant fiber-1 protein produced in this study can serve as a subunit vaccine to control HPS in chickens.

A novel subunit vaccine based on Fiber1/2 knob domain provides full protection against fowl adenovirus serotype 4 and induces stronger immune responses than a Fiber2 subunit vaccine

“…All of these revealed that Fiber2 subunit vaccine could induce the cellular immune responses and humoral immune response ( Yin et al, 2021 ). However, Fiber1 is also immunogenic and has a protective effect against FAdV-4, it can induce high level of neutralizing antibodies in immunized chickens ( Wang et al, 2018 ; Watanabe et al, 2023 ). Both Fiber2 and Fiber1 knob domains are their main functional areas and are key domains for their immune effects ( Song et al, 2023 ).…”