Molecular Analysis of the Avian H7 Influenza Viruses Circulating in South Korea during 2018-2019: Evolutionary Significance and Associated Zoonotic Threats.

Bao Tuan Duong,Haan Woo Sung,Jyotiranjan Bal,Seon-Ju Yeo,Hyun Park

doi:10.3390/v13112260

Bao Tuan Duong, Haan Woo Sung + Show 3 more

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https://doi.org/10.3390/v13112260

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Abstract

Avian influenza virus (AIV) subtypes H5 and H7, possessing the ability to mutate spontaneously from low pathogenic (LP) to highly pathogenic (HP) variants, are major concerns for enormous socio-economic losses in the poultry industry, as well as for fatal human infections. Through antigenic drift and shift, genetic reassortments of the genotypes pose serious threats of increased virulence and pathogenicity leading to potential pandemics. In this study, we isolated the H7-subtype AIVs circulating in the Republic of Korea during 2018–2019, and perform detailed molecular analysis to study their circulation, evolution, and possible emergence as a zoonotic threat. Phylogenetic and nucleotide sequence analyses of these isolates revealed their distribution into two distinct clusters, with the HA gene sharing the highest nucleotide identity with either the A/common teal/Shanghai/CM1216/2017, isolated from wild birds in Shanghai, China, or the A/duck/Shimane/2014, isolated from Japan. Mutations were found in HA (S138A (H3 numbering)), M1 (N30D and T215A), NS1 (P42S), PB2 (L89V), and PA (H266R and F277S) proteins—the mutations had previously been reported to be related to mammalian adaptation and changes in the virulence of AIVs. Taken together, the results firmly put forth the demand for routine surveillance of AIVs in wild birds to prevent possible pandemics arising from reassortant AIVs.

Highlights

Influenza A viruses (IAV), belonging to the family Orthomyxoviridae, possess the ability to adapt to multiple hosts, including wildlife, domestic animals, and humans, causing yearly outbreaks with high rates of morbidity and fatality [1]
During 2018–2019, we isolated a total of 14 H7 isolates from wild bird habitats in the Republic of Korea, out of which, nine were isolated in 2018, and five in 2019
GenBank accession numbers of the eight gene segments and the highest nucleotide identities from the GenBank database are shown in Tables S1–S13, with sequence identities from 98.16 to 99.12% when compared to other IAV sequences

Summary

Introduction

Influenza A viruses (IAV), belonging to the family Orthomyxoviridae, possess the ability to adapt to multiple hosts, including wildlife, domestic animals, and humans, causing yearly outbreaks with high rates of morbidity and fatality [1]. The virus can reassort or mutate continuously to acquire point mutations while circulating in several hosts, ranging from aquatic birds to mammals, including humans. IAV can be transmitted from wild birds to domestic birds, causing large scale mortality, sporadically followed by transmission to humans, commonly referred to as zoonotic infections [2]. Genetic reassortments between avian influenza viruses affecting different species, and their attainable human transmission, continue to pose a serious challenge to the prediction of, and ground level readiness to deal with, the emergence of new pandemic viruses. An interesting characteristic of the AIV H7 subtype is interspecies

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