Genetically Divergent Highly Pathogenic Avian Influenza A(H5N8) Viruses in Wild Birds, Eastern China

Abstract

H ighly pathogenic avian infl uenza (HPAI) A(H5Nx) clade 2.3.4.4 viruses, which originated from the HPAI A(H5N1) clade 2.3.4 of the A/ Goose/Guangdong/1/96-lineage in China, have spread globally, causing severe disease in poultry and wild birds (1-4). According to the World Health Organization, clade 2.3.4.4 viruses have evolved into 8 subclades, designated as clades 2.3.4.4a-h (https://www.who.int/influenza/vaccines/virus/202002_zoonotic_vaccinevirusupdate.pdf). In 2013, a novel reassortant A(H5N8) clade 2.3.4.4b virus was isolated from domestic ducks in eastern China (2); this virus was later detected in Korea and Japan (3). Since 2014, clade 2.3.4.4b viruses have spread to Europe and Africa along the migratory fl yways of birds (4,5). These introductions caused large HPAI outbreaks in wild and domestic birds in Europe during the winter of 2016-17 (6). At the same time, wild birds carried clade 2.3.4.4c viruses to North America (4).In early 2020, outbreaks of clade 2.3.4.4b viruses mainly occurred in Europe (7). Beginning in July 2020, several outbreaks of H5N8 viruses in poultry and wild birds were reported in Eurasia, including Kazakhstan,

Genetic and biological characteristics of the globally circulating H5N8 avian influenza viruses and the protective efficacy offered by the poultry vaccine currently used in China

“…H5N8 viruses have been circulating in wild birds since 2014, and are responsible for numerous disease outbreaks in domestic poultry in many countries in Asia, Europe, Africa, and North America (Abolnik et al, 2019;Baek et al, 2021;El-Shesheny et al, 2021;Lee et al, 2015;Napp et al, 2018); however, even though different H5N8 strains have been detected in wild birds and occasionally in ducks or geese in past years, they have not become established in domestic waterfowls and spread or have caused problems in chickens in China. In this study and the studies reported by others (He et al, 2021;Li et al, 2021;Xiong et al, 2021), H5N8 viruses were detected in over 17 different species of wild birds over just a few months. Since it is impossible to prevent wild birds from being infected with the virus, the H5N8 virus may have a high probability of circulation in wild birds in China.…”

Emergence, Evolution, and Biological Characteristics of H10N4 and H10N8 Avian Influenza Viruses in Migratory Wild Birds Detected in Eastern China in 2020

“…Widely circulated wild-bird AIVs can be introduced into domestic poultry by migratory birds and domestic waterfowl, thereby increasing the risk of cross-species transmission between birds and mammals. The H5N8 viruses continually circulate in migratory birds in Asia, Europe, North America, and Africa and are highly likely to generate novel mutants by reassortment with other subtypes ( 52 – 54 ). Currently, the H10 viruses are divided into Eurasian and North American lineages and are widely circulating in both wild migratory birds and domestic poultry ( 32 , 46 ).…”

Emergence, prevalence, and evolution of H5N8 avian influenza viruses in central China, 2020

“…In the Maximum-likelihood (ML) phylogenies of the H5 gene, 2020-H5N8 (n = 40) and SX116-H5N2 were both classified in 2.3.4.4b, and were further diverged into two phylogenetically distinct sub-clades: 2.3.4.4b1 and 2.3.4.4b2 ( Figure 1 ) [ 7 , 32 , 33 ]. The high bootstrap value also supported the two novel sub-clades.…”