Emergence and spread of novel H5N8, H5N5 and H5N1 clade 2.3.4.4 highly pathogenic avian influenza in 2020

Abstract

Analyses of HPAI H5 viruses from poultry outbreaks across a wide Eurasian region since July 2020 including the Russian Federation, Republics of Iraq and Kazakhstan, and recent detections in migratory waterfowl in the Netherlands, revealed undetected maintenance of H5N8, likely in galliform poultry since 2017/18 and both H5N5 and H5N1. All viruses belong to A/H5 clade 2.3.4.4b with closely related HA genes. Heterogeneity in Eurasian H5Nx HPAI emerging variants threatens poultry production, food security and veterinary public health.

Multiple Reassortants of H5N8 Clade 2.3.4.4b Highly Pathogenic Avian Influenza Viruses Detected in South Korea during the Winter of 2020–2021

“…On the other hand, cluster G2 had a close genetic relationship with the H5N8 clade 2.3.4.4b viruses that have been identified in the Republic of Iraq, Italy, and England since May 2020 [19], and shared a common ancestor with the viruses detected in Europe during late 2020, suggesting that it was most likely disseminated through overlapping breeding areas between Europe and South Korea during fall 2020. The phylogenetic analysis of the HA gene of the HPAI H5N8 viruses detected in South Korea showed that all the isolates belong to H5 clade 2.3.4.4b and form two distinct genetic groups (G1 and G2), suggesting separate introductions of two genetically distinct H5N8 clade 2.3.4.4 viruses ( Figure 2).…”

“…On the other hand, cluster G2 had a close genetic relationship with the H5N8 clade 2.3.4.4b viruses that have been identified in the Republic of Iraq, Italy, and England since May 2020 [19], and shared a common ancestor with the viruses detected in Europe during late 2020, suggesting that it was most likely disseminated through overlapping breeding areas between Europe and South Korea during fall 2020. Maximum clade credibility (MCC) trees of hemagglutinin gene of H5N8 highly pathogenic avian influenza viruses isolated in South Korea during the winter of 2020-2021 (time shown on the horizontal axis) were inferred using an uncorrelated lognormal distribution relaxed clock in Beast v1.10.4.…”

“…The genome constellation of the virus detected in Iraq was distinct from that of the reassortant viruses detected in Europe during early 2020. Furthermore, reassortant H5N1 and H5N5 viruses related to the H5N8 virus reported in Iraq were detected in the Netherlands and Germany [19].…”

“…Additional genome sequencing data for H5N8 HPAI viruses isolated from wild birds in Korea would provide insight into the evolutionary history of the viruses, since the present study included only a limited number of H5N8 HPAI virus samples isolated from wild birds. [17,18]; blue, late 2020 H5N8 Europe HPAI virus [19]; green, red, purple, orange, dark orange, and cyan blue, Eurasian low pathogenic avian influenza viruses.…”

“…Subsequently, several outbreaks in poultry and wild birds caused by this reassortant HPAI virus were reported in multiple European countries, including Poland, the Czech Republic, Hungary, and Germany, up to April 2020 [18]. In May 2020, the Republic of Iraq reported a novel H5N8 clade 2.3.4.4b HPAI virus in poultry that is genetically close to the H5N8 2.3.4.4b HPAI virus that circulated in Eurasia during 2017-2018 [19]. The genome constellation of the virus detected in Iraq was distinct from that of the reassortant viruses detected in Europe during early 2020.…”