Genetic characterization of novel fowl aviadenovirus 4 isolates from outbreaks of hepatitis-hydropericardium syndrome in broiler chickens in China

Abstract

Since May 2015, severe outbreaks of hepatitis-hydropericardium syndrome (HHS) associated with infections of fowl aviadenovirus (FAdV) have emerged in broiler chickens in several Chinese provinces. To identify the genotype and gain a better understanding of the genetic properties of the FAdV strains responsible for the recent HHS outbreaks in China, the complete genome sequences of five isolates from outbreaks of HHS in broiler chickens in five provinces were determined. The results demonstrated that a novel fowl aviadenovirus 4 (FAdV-4) genotype was epidemic in China. To investigate the molecular characteristics of these Chinese FAdV-4 isolates, their genome contents were compared with those of reported pathogenic and non-pathogenic FAdV-4 strains. The comparative analysis revealed that the novel Chinese FAdV-4 isolates contain various genomic deletions and multiple distinct amino-acid mutations in their major structural genes. Two additional putative genetic virulence markers in the fiber 2 gene were identified. These findings confirmed some of the genetic differences between the pathogenic and non-pathogenic FAdV-4 isolates. The data presented in this report will enhance the current understanding of the molecular epidemiology and genetic diversity of FAdV-4 isolates in China and will provide additional insight into the critical factors that determine the pathogenicity of FAdV-4 strains. Finally, the emergence of this novel and highly pathogenic FAdV-4 genotype emphasizes that preventive measures against FAdV-4 infections on poultry farms should be implemented in China.

Different Dynamic Distribution in Chickens and Ducks of the Hypervirulent, Novel Genotype Fowl Adenovirus Serotype 4 Recently Emerged in China

“…The FAdV-4 that caused a recent epidemic in China was isolated and characterized as a novel genotype of FAdV-4 (Liu et al, 2016; Ye et al, 2016). Although many studies have been conducted on virus isolation, characterization and pathogenicity to chickens of the novel FAdV-4, less is known about the replicator dynamics in vivo , which is critical for enclosing the pathogenesis of the emerged novel FAdV-4.…”

Identification of chicken CAR homology as a cellular receptor for the emerging highly pathogenic fowl adenovirus 4 via unique binding mechanism

“…FAdV-B (serotype FAdV-5), FAdV-D (serotypes FAdV-2, -3, -9, and -11), and FAdV-E (serotypes FAdV-6, -7, -8a, and -8b) each have a unique single fibre, whereas FAdV-A (serotype FAdV-1) and FAdV-C (serotypes FAdV-4 and -10) have two distinct fibres inserted in each penton base. Although both the emerging novel genotype FAdV-4 and FAdV-1 have two fibres in each penton, their fibre patterns are differ significantly [24]. Long fibre 1 of CELO (an FAdV-1 type strain) has 710 amino acids (aa), whereas short fibre 2 has 410 aa [25].…”

“…Long fibre 1 of CELO (an FAdV-1 type strain) has 710 amino acids (aa), whereas short fibre 2 has 410 aa [25]. In contrast, fibre 1 of the novel FAdV-4 has 431 aa, whereas fibre 2 has 479 aa [24], suggesting that fibre 1 might be the short fibre of FAdV-4. The unique fibre pattern of FAdV-4 implies that a novel fibrereceptor-interaction mechanism occurs in FAdV-4infected host cells.…”

Fowl Adenovirus (FAdV) Recombination with Intertypic Crossovers in Genomes of FAdV-D and FAdV-E, Displaying Hybrid Serological Phenotypes

“…For genomes of contemporary field strains, there had so far only been singular contributions to public databases. Recently, this situation has changed for FAdV-4 (FAdV-C), with the sudden appearance of hepatitis-hydropericardium syndrome (HHS) in China, leading to an extensive supply of the relevant sequences [10][11][12].…”