Emergence and Evolution of H10 Subtype Influenza Viruses in Poultry in China

Abstract

The cases of human infections with H10N8 viruses identified in late 2013 and early 2014 in Jiangxi, China, have raised concerns over the origin, prevalence, and development of these viruses in this region. Our long-term influenza surveillance of poultry and migratory birds in southern China in the past 12 years showed that H10 influenza viruses have been introduced from migratory to domestic ducks over several winter seasons at sentinel duck farms at Poyang Lake, where domestic ducks share their water body with overwintering migratory birds. H10 viruses were never detected in terrestrial poultry in our survey areas until August 2013, when they were identified at live-poultry markets in Jiangxi. Since then, we have isolated 124 H10N8 or H10N6 viruses from chickens at local markets, revealing an ongoing outbreak. Phylogenetic analysis of H10 and related viruses showed that the chicken H10N8 viruses were generated through multiple reassortments between H10 and N8 viruses from domestic ducks and the enzootic chicken H9N2 viruses. These chicken reassortant viruses were highly similar to the human isolate, indicating that market chickens were the source of human infection. Recently, the H10 viruses further reassorted, apparently with H5N6 viruses, and generated an H10N6 variant. The emergence and prevalence of H10 viruses in chickens and the occurrence of human infections provide direct evidence of the threat from the current influenza ecosystem in China. IMPORTANCEAfter the outbreak of avian-origin H7N9 influenza viruses in China, fatal human infections with a novel H10N8 virus were reported. Utilizing data from 12 years of influenza surveillance in southern China, we showed that H10 viruses were regularly introduced by migratory ducks to domestic ducks on Poyang Lake, a major aggregative site of migratory birds in Asia. The H10 viruses were maintained and amplified in domestic ducks and then transmitted to chickens and reassorted with enzootic H9N2 viruses, leading to an outbreak and human infections at live-poultry markets. The emergence of the H10N8 virus, following a pathway similar to that of the recent H7N9 virus, highlights the role of domestic ducks and the current influenza ecosystem in China that facilitates influenza viruses moving from their reservoir hosts through the live-poultry system to cause severe consequences for public health.

Diversity and evolution of avian influenza viruses in live poultry markets, free-range poultry and wild wetland birds in China

“…Hence, LPMs represent an ideal breeding ground for the generation of novel AIV variants and for secondary contact with susceptible human populations. Indeed, it is likely that many novel AIVs, including the human-infecting H5N1, H7N9 and H10N8, originated in LPMs (Guan et al, 1999;Li et al, 2004;Ma et al, 2015). For example, the core component of these viruses are from H9N2 viruses, which is the dominant subtype in the LPMs from Hubei and Zhejiang provinces as well as many other places in China.…”

Detection of Avian H7N9 Influenza A Viruses in the Yangtze Delta Region of China During Early H7N9 Outbreaks

“…Domestic duck facilitates the interaction between genetic pools in wild bird and domestic poultry, maintained the wild bird-origin virus and spread it to chicken (9). More recently, the emergence of H10N8 viruses in Southern China highlights the threat brought by the current influenza ecosystem (16). Based on the finding in this study and early research, we propose a simple model to describe the emergence and spread of the novel H7N9 virus (Figure 2).…”

Extended full-genome phylogenetic analysis of the first human A/H5N1 avian influenza case in North America

“…Here it is provisionally denoted as 2.3.2.1-C 0 for convenience. Different to the seven gene segments (PB1, PA, HA, NP, NA, MP, NS) that belong to avian H5N1 clade 2.3.2.1-C 0 , the PB2 gene of ALB1 is derived from the H9N2 ZJ-HJ/ 07 sublineage, which is also the source of the PB2 and other internal genes in the H7N9 and H10N8 viruses that have caused human infections in China since February 2013 (Chen et al, 2014;Lam et al, 2013bLam et al, , 2015Liu et al, 2013;Ma et al, 2015) (Fig. S2).…”