Subclinical Infection and Transmission of Clade 2.3.4.4 H5N6 Highly Pathogenic Avian Influenza Virus in Mandarin Duck (Aix galericulata) and Domestic Pigeon (Columbia livia domestica).

Sol Jeong,Weon-Hwa Jheong,Jei-Hyun Jeong,Yu-Jin Kim,Sun-Hak Lee,Jung-Eun Park,Jung-Hoon Kwon,Dong-Hun Lee,Chang-Seon Song

doi:10.3390/v13061069

Abstract

Since 2014, H5Nx clade 2.3.4.4 highly pathogenic avian influenza viruses (HPAIV) have caused outbreaks in wild birds and poultry in multiple continents, including Asia, Europe, Africa, and North America. Wild birds were suspected to be the sources of the local and global spreads of HPAIV. This study evaluated the infectivity, pathogenicity, and transmissibility of clade 2.3.4.4 H5N6 HPAIV in mandarin ducks (Aix galericulata) and domestic pigeons (Columbia livia domestica). None of the birds used in this study, 20 mandarin ducks or 8 pigeons, showed clinical signs or mortality due to H5N6 HPAI infection. Two genotypes of H5N6 HPAIV showed replication and transmission by direct and indirect contact between mandarin ducks. H5N6 HPAIV replicated and transmitted by direct contact between pigeons, although the viral shedding titer and duration were relatively lower and shorter than those in mandarin ducks. Influenza virus antigen was detected in various internal organs of infected mandarin ducks and pigeons, indicating systemic infection. Therefore, our results indicate mandarin ducks and pigeons can be subclinically infected with clade 2.3.4.4 H5N6 HPAIV and transfer the virus to adjacent birds. The role of mandarin ducks and pigeons in the spread and prevalence of clade 2.3.4.4 H5N6 viruses should be carefully monitored.

Highlights

After the discovery of A/goose/Guangdong/1/1996(H5N1) (Gs/GD), a highly pathogenic avian influenza (HPAI) virus in China, global spread of Gs/GD-lineage H5 HPAI viruses has been observed, and the viruses have evolved into phylogenetically distinct clades (0–9) and subclades by genetic drift and shift [1]
Detections of clade 2.3.4.4 H5N6 HPAI virus in wild migratory or terrestrial birds and subclinical infections in these birds are of concern due to the possibility that these birds could maintain the virus and further spread outside of Asia
This study investigated the pathogenicity and transmissibility of clade 2.3.4.4 H5N6 HPAI in mandarin ducks and domestic pigeons

Summary

Introduction

After the discovery of A/goose/Guangdong/1/1996(H5N1) (Gs/GD), a highly pathogenic avian influenza (HPAI) virus in China, global spread of Gs/GD-lineage H5 HPAI viruses has been observed, and the viruses have evolved into phylogenetically distinct clades (0–9) and subclades by genetic drift and shift [1]. Since 2014, H5N6 and H5N8 subtypes of viruses bearing the hemagglutinin (HA) gene of clade 2.3.4.4 have been detected in wild birds and poultry in multiple continents, including Asia, Europe, Africa, and North America. They have become the dominant subtypes of the Gs/Gd lineage [5,6,7,8,9,10]. The clade 2.3.4.4 HPAI H5N6 viruses, which have been the dominant subtype in China, have evolved into multiple genotypes and caused infection in multiple species, including mammalian species and humans [15,16,17,18]. The spread of clade 2.3.4.4 H5N6 viruses could be a severe threat to the poultry industry and public health

Methods

Results

Conclusion