Historical Investigation of Fowl Adenovirus Outbreaks in South Korea from 2007 to 2021: A Comprehensive Review.

Jongseo Mo

doi:10.3390/v13112256

Abstract

Fowl adenoviruses (FAdVs) have long been recognized as critical viral pathogens within the poultry industry, associated with severe economic implications worldwide. This specific group of viruses is responsible for a broad spectrum of diseases in birds, and an increasing occurrence of outbreaks was observed in the last ten years. Since their first discovery forty years ago in South Korea, twelve antigenically distinct serotypes of fowl adenoviruses have been described. This comprehensive review covers the history of fowl adenovirus outbreaks in South Korea and updates the current epidemiological landscape of serotype diversity and replacement as well as challenges in developing effective broadly protective vaccines. In addition, transitions in the prevalence of dominant fowl adenovirus serotypes from 2007 to 2021, alongside the history of intervention strategies, are brought into focus. Finally, future aspects are also discussed.

Highlights

Since the first discovery of fowl adenoviruses (FAdVs) in 1949, for decades, they have been recognized as critical viral pathogens within the poultry sector due to their widespread occurrence and economic implications worldwide [1]
Fowl adenoviruses (FAdVs) outbreaks can cause significant economic impacts on the poultry industry, from poor performance and growth retardations to flock mortalities. These isometric non-enveloped viruses belong to the family Adenoviridae, genus Aviadenovirus, and carry a double-stranded DNA genome with a size of ~45 kb
Twelve (1 to 8a and 8b to 11) serotypes based on their restriction fragment length polymorphism (RFLP) profiles in the hexon gene, which act as subtype-specific antigenic determinants [2,3,4]

Summary

Introduction

Since the first discovery of fowl adenoviruses (FAdVs) in 1949, for decades, they have been recognized as critical viral pathogens within the poultry sector due to their widespread occurrence and economic implications worldwide [1]. Depending on the strain’s pathogenicity, cases of vertical transmission can result in significantly decreased weight gain alongside adverse effects on other production parameters, leading to severe economic losses [17] Such situations have grave repercussions from the producer’s point of view, since affected birds are unlikely to recover from growth retardation until the harvest age. The cases were evenly spread across all eight provinces, and documented mortalities of infected flocks ranged from 0.01% to 55% between 2007 and 2010 [55] but sharply declined after that period to 0.5–4% due to heightened biosecurity and implementation of vaccination programs [45,56,57] The purpose of this comprehensive review is to provide an overview of the history and status of FAdV outbreaks in South Korea and to update the epidemiological situation that was observed in recent years. Case numbers are based on published literature [45,55,58,59,60] and unpublished data (Supplementary Materials). 2 None reported

FAdV Outbreaks in 2007–2012

Development of Domestic FAdV Vaccines

FAdV Outbreaks in 2013–2021

Findings

Current Status and Future Perspectives