Identification of a novel immunological epitope on Hexon of fowl adenovirus serotype 4

Abstract

Fowl adenovirus serotype 4 (FAdV-4), the causative agent of hepatitis-hydropericardium syndrome (HHS), distributed widely in the poultry farms in China. Hexon is one of the major capsid proteins associated with viral species or serotypes. However, the epitopes of Hexon protein remain largely unknown. In this study, a monoclonal antibody (mAb) specific to Hexon protein of FAdV-4, designated as 3G8, was generated. Subsequently, the linear peptide recognized by 3G8 was mapped and identified as 213AYGAYVK219 using a series of overlapping peptides generated from Hexon protein. Amino acid sequence analysis revealed that the epitope recognized by 3G8 was highly conserved across all the FAdVs. The epitope was immunogenic and could be recognized by FAdV-4 positive chicken serum samples. These findings will enrich our knowledge regarding the epitope on Hexon and provide valuable information for further characterization of the antigenicity of Hexon protein.

Conflicting Evidence between Clinical Perception and Molecular Epidemiology: The Case of Fowl Adenovirus D

“…The study of the selective pressures highlighted a much more intense positive selection on sites exposed to the viral surface [55,56]. The role of host immunity, natural or acquired through vaccination, in driving Hexon evolution is thus likely, although none of the herein reported sites was located in previously identified epitopes [4]. Of note, several sites within the Hexon trimer were reported under episodic diversifying selection.…”

“…The sequencing of the Hexon gene, the main constituent of the viral capsid, has been traditionally used to categorize aviadenoviruses in species and even at the below-species level [2,3]. In addition to the application in molecular characterization, the Hexon gene contains antigenic determinants, including neutralizing ones [4]. Different species and serotypes have been associated with variable clinical syndromes; inclusion body hepatitis (IBH) is mainly caused by strains of FAdV-2, -3, -9 and -11 serotypes (FAdV-D species) and FAdV-6, -7, -8a and -8b serotypes (FAdV-E species), while hydropericardium syndrome (HPS) is linked especially to FAdV-4 of the species FAdV-C and adenoviral gizzard erosion (AGE) to FAdV-1 (FAdV-A species), although minor exceptions are documented [1,5].…”

Efficient cross-protection against serotype 4/8a fowl adenoviruses (FAdVs): recombinant FAdV-4 with FAdV-8a Fiber

“…All the FAdVs were propagated in LMH cells maintained in DMEM/F12 medium containing 1% FBS. Monoclonal antibodies (mAb) 1B5 against hexon of FAdV were kindly provided by Professor Hongjun Chen ( 25 ), and pAbs against Fiber of FAdV-8a were collected from the mice immunized with purified GST-Fiber (FAdV-8a) and stored in our laboratory.…”

Biological features of fowl adenovirus serotype-4

“…Similarly, coinfection of chickens with FAdV-4 and chicken infectious anemia virus (CIAV) and Avibacterium paragallinarum resulted in significantly increased mortality compared to with infection caused by FAdV-4 alone ( Mei et al., 2020 ). However, coinfection of FAdV-4 with serotype FAdV-8a in specific-pathogen-free (SPF) chickens resulted in decreased proliferation and replication of FAdV-4 while enhancing the proliferation and replication of FAdV-8a in chickens ( Liu et al., 2021 ). A recent study compared coinfection with FAdV-4 and duck circovirus (DuCV) and monoinfection ( Shen et al., 2023 ).…”