Pathobiological Characterization of a Novel Reassortant Highly Pathogenic H5N1 Virus Isolated in British Columbia, Canada, 2015.

Yohannes Berhane,Mathew Suderman,Shawn Babiuk,Tomy Joseph,Colleen Cottam-Birt,Victoria Bowes,Brad Pickering,John Pasick,Tamiko Hisanaga,Darwyn Kobasa,Anders Leung,Carissa Embury-Hyatt

doi:10.1038/srep23380

Abstract

In the current study, we describe the pathobiologic characteristics of a novel reassortant virus - A/chicken/BC/FAV-002/2015 (H5N1) belonging to clade 2.3.4.4 that was isolated from backyard chickens in British Columbia, Canada. Sequence analyses demonstrate PB1, PA, NA and NS gene segments were of North American lineage while PB2, HA, NP and M were derived from a Eurasian lineage H5N8 virus. This novel virus had a 19 amino acid deletion in the neuraminidase stalk. We evaluated the pathogenic potential of this isolate in various animal models. The virus was highly pathogenic to mice with a LD50 of 10 plaque forming units (PFU), but had limited tissue tropism. It caused only subclinical infection in pigs which did result in seroconversion. This virus was highly pathogenic to chickens, turkeys, juvenile Muscovy ducks (Cairnia moschata foma domestica) and adult Chinese geese (Anser cynoides domesticus) causing a systemic infection in all species. The virus was also efficiently transmitted and resulted in mortality in naïve contact ducks, geese and chickens. Our findings indicate that this novel H5N1 virus has a wide host range and enhanced surveillance of migratory waterfowl may be necessary in order to determine its potential to establish itself in the wild bird reservoir.

Highlights

In December 2014, a highly pathogenic avian influenza (HPAI) outbreak due to a novel reassortant H5N2 virus was reported near Abbotsford, British Columbia[1]
In December 2014, an outbreak of HPAI caused by a novel reassortant H5N2 virus with a Gs/ Gd-like HA gene belonging to clade 2.3.4.4 was reported in the lower Fraser Valley of British Columbia, Canada[1]
Sequence analyses demonstrated that 4 gene segments - basic polymerase 1 (PB1), acidic polymerase (PA), neuraminidase (NA) and non-structural (NS) were derived from an unknown virus of North American lineage; the basic polymerase 2 (PB2), hemagglutinin (HA), nucleoprotein (NP) and matrix (M) segments were derived from a Eurasian lineage H5N8 virus

Summary

Introduction

In December 2014, a highly pathogenic avian influenza (HPAI) outbreak due to a novel reassortant H5N2 virus was reported near Abbotsford, British Columbia[1] This outbreak was extraordinary in that it was the first reported case involving the transcontinental spread of Eurasian A/Goose/Guangdong/1/96- like HPAI H5N1 lineage (Gs/Gd like-lineage) viruses to North America. In December 2014, an outbreak of HPAI caused by a novel reassortant H5N2 virus with a Gs/ Gd-like HA gene belonging to clade 2.3.4.4 was reported in the lower Fraser Valley of British Columbia, Canada[1]. This virus consisted of a mixture of gene segments of Eurasian HPAI H5N8 virus and North American lineage low pathogenic virus origin. Previous reports involving natural or experimental infections with Gs/Gd-like HPAI H5N1 viruses showed that they could replicate and efficiently transmit in ducks, the pathogenicity ranged widely from sub-clinical infection to clinical disease with mortality

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