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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Exotic & Emerging Avian Viral Diseases Research » Research » Publications at this Location » Publication #375961

Research Project: Intervention Strategies to Prevent and Control Disease Outbreaks Caused by Emerging Strains of Avian Influenza Viruses

Location: Exotic & Emerging Avian Viral Diseases Research

Title: Phylogenetic analyses of the H7N3 low and high pathogenicity avian influenza viruses causing an outbreak in turkeys in North and South Carolina in 2020

item YOUK, SONGSU - Orise Fellow
item LEE, DONG-HUN - University Of Connecticut
item KILLIAN, MARY - Animal And Plant Health Inspection Service (APHIS)
item Pantin Jackwood, Mary
item Swayne, David
item TORCHETTI, MIA - Animal And Plant Health Inspection Service (APHIS)

Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 7/26/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: High pathogenicity avian influenza viruses (HPAIV) have devastating impacts on the poultry industries. In March 2020, an outbreak of H7N3 low pathogenicity avian influenza (LPAI) occurred on 9 turkey farms in North Carolina (NC) and a farm in South Carolina (SC). On a second turkey flock in SC that had increased mortality and respiratory signs, a H7N3 HPAIV was detected. The virus mutated to the highly pathogenic form via a 27-nucleotide host cellular 28S rRNA insertion in the hemagglutinin (HA) gene near the hemagglutinin cleavage site. Another notable change was a 66-nucleotide deletion in the NA stalk region of viruses from two premises in NC. The NA stalk deletions are commonly associated with adaptation of wild bird influenza viruses to gallinaceous poultry. All the premises affected by H7N3 LPAIV and HPAIV were located in three adjacent counties, one across state lines, indicating that geographical proximity was relevant to the outbreaks. Immediate depopulation was performed on affected premises for a total of 361,000 birds. Complete genome sequencing and phylogenetic analyses indicated the wild bird origin of the H7N3 viruses. The H7 HA genes of recent U.S. poultry events (2016, 2017, and 2020) originate from the same North American wild bird H7 lineage. With several recent incursions, this H7 HA clade represents a repetitive threat to domestic poultry and carries with it the potential to mutate to HPAIV.