Reassortant Highly Pathogenic Influenza A H5N2 Virus Containing Gene Segments Related to Eurasian H5N8 in British Columbia, Canada, 2014

Abstract

In late November 2014 higher than normal death losses in a meat turkey and chicken broiler breeder farm in the Fraser Valley of British Columbia initiated a diagnostic investigation that led to the discovery of a novel reassortant highly pathogenic avian influenza (HPAI) H5N2 virus. This virus, composed of 5 gene segments (PB2, PA, HA, M and NS) related to Eurasian HPAI H5N8 and the remaining gene segments (PB1, NP and NA) related to North American lineage waterfowl viruses, represents the first HPAI outbreak in North American poultry due to a virus with Eurasian lineage genes. Since its first appearance in Korea in January 2014, HPAI H5N8 spread to Western Europe in November 2014. These European outbreaks happened to temporally coincide with migratory waterfowl movements. The fact that the British Columbia outbreaks also occurred at a time associated with increased migratory waterfowl activity along with reports by the USA of a wholly Eurasian H5N8 virus detected in wild birds in Washington State, strongly suggest that migratory waterfowl were responsible for bringing Eurasian H5N8 to North America where it subsequently reassorted with indigenous viruses.

Pathogenicity and Transmission of H5 and H7 Highly Pathogenic Avian Influenza Viruses in Mallards

“…This virus exhibited the widest geographic spread in the United States. The H5N2 HPAI virus is composed of five gene segments (PB2, PA, HA, M, and NS) related to the Eurasian HPAI H5N8, and the remaining gene segments (PB1, NP, and NA) are related to North American lineage waterfowl viruses (32,34,35). Interestingly, clinical signs and mortality have been described in domestic ducks infected with Gs/GD lineage H5 clade 2.3.4.4 HPAI viruses (75).…”

“…Concurrently, this virus was detected in the United States in captive falcons, wild birds, and backyard aquatic and gallinaceous poultry (34). In addition, another novel reassortant HPAI virus of H5 clade 2.3.4.4 (H5N2) was identified as the cause of an outbreak in poultry farms in British Columbia, Canada (35), and was subsequently detected in the United States in wild waterfowl and backyard poultry. From March to June 2015, the H5N2 reassortant virus was found in wild aquatic birds, raptors, and backyard and commercial poultry flocks in the Midwestern region of the United States (36).…”

Hemagglutinin-Neuraminidase Balance Influences the Virulence Phenotype of a Recombinant H5N3 Influenza A Virus Possessing a Polybasic HA 0 Cleavage Site

“…In late November 2014, a novel reassortant HPAI H5N2 virus that contained gene segments related to Eurasian H5N8 was detected in a domestic turkey and broiler breeder flock in British Columbia, Canada (42). Shortly thereafter, Eurasian HPAI H5N8 and reassortant HPAI H5N2 viruses were isolated from wild birds in Washington, USA (43).…”

Intercontinental Spread of Asian-Origin H5N8 to North America through Beringia by Migratory Birds

“…Verhagen et al hypothesized that the timing and direction of intercontinental spread coincided with autumn bird migration out of Russia; the H5N8 virus was identified in a long-distance migratory bird in Russia in September 2014 and subsequently in Japan and Europe, and on the west coast of North America (9). Similarly, wide geographic dissemination of the Gs/GD lineage virus was seen between 2005 and 2006, as clade 2.2 viruses spread from Qinghai Lake, China, to Siberia and then to various countries of Asia, Europe, and Africa (2,10 (8,11). Both the H5N8 and H5N2 reassortants have been detected in wild waterfowl, as well as backyard and commercial poultry along the Pacific flyway (8,12).…”