Isolation and Genomic Characterization of Avian Reovirus From Wild Birds in South Korea.

Sang-Won Kim,Min Kang,Yu-Ri Choi,Se-Yeoun Cha,Jun-Feng Zhang,Hyung-Kwan Jang,Ke Shang,Bai Wei,Jong-Yeol Park

doi:10.3389/fvets.2022.794934

Abstract

Avian reoviruses (ARVs) cause severe arthritis, tenosynovitis, pericarditis, and depressed growth in chickens, and these conditions have become increasingly frequent in recent years. Studies on the role of wild birds in the epidemiology of ARVs are insufficient. This study provides information about currently circulating ARVs in wild birds by gene detection using diagnostic RT-PCR, virus isolation, and genomic characterization. In this study, we isolated and identified 10 ARV isolates from 7,390 wild birds' fecal samples, including migratory bird species (bean goose, Eurasian teal, Indian spot-billed duck, and mallard duck) from 2015 to 2019 in South Korea. On comparing the amino acid sequences of the σC-encoding gene, most isolates, except A18-13, shared higher sequence similarity with the commercial vaccine isolate S1133 and Chinese isolates. However, the A18-13 isolate is similar to live attenuated vaccine av-S1133 and vaccine break isolates (SD09-1, LN09-1, and GX110116). For the p10- and p17-encoding genes, all isolates have identical fusion associated small transmembrane (FAST) protein and nuclear localization signal (SNL) motif to chicken-origin ARVs. Phylogenetic analysis of the amino acid sequences of the σC-encoding gene revealed that all isolates were belonged to genotypic cluster I. For the p10- and p17-encoding genes, the nucleotide sequences of all isolates indicated close relationship with commercial vaccine isolate S1133 and Chinese isolates. For the σNS-encoding gene, the nucleotide sequences of all isolates indicated close relationship with the Californian chicken-origin isolate K1600657 and belonged to chicken-origin ARV cluster. Our data indicates that wild birds ARVs were derived from the chicken farms. This finding suggests that wild birds serve as natural carriers of such viruses for domestic poultry.

Highlights

Avian reoviruses (ARVs), classified under the Orthoreovirus genus of Reoviridae family, have a non-enveloped icosahedral double capsid with 10 double-stranded RNA genome segments which are further divided into three size classes based on their electrophoretic mobility: large (L1, L2, L3), medium (M1, M2, M3), and small (S1, S2, S3, S4) [1]
The σNS protein encoded by the segment S4, has been reported for its single-stranded RNA binding activity, and it is divided into diverse lineages that conserved by host origin of ARVs [10, 11]; as well it has been used for diagnostic analysis [10, 12]
Five ARVs were detected from bean goose (Anser fabalis), one from mallard duck (Anas platyrhtchos), one from Eurasian teal (Anas crecca), one from oriental turtle dove (Streptopelia orientalis), and one from Indian spot-billed duck (Anas poecilorhyncha); the source could not be identified for one ARV (Table 2)

Summary

Introduction

Avian reoviruses (ARVs), classified under the Orthoreovirus genus of Reoviridae family, have a non-enveloped icosahedral double capsid with 10 double-stranded RNA (dsRNA) genome segments which are further divided into three size classes based on their electrophoretic mobility: large (L1, L2, L3), medium (M1, M2, M3), and small (S1, S2, S3, S4) [1]. ARV genome encodes eight structural (λA, λB, λC, μA, μB, σA, σB, and σC) and four non-structural viral proteins (μNS, σNS, p10, and p17) [2]. The σNS protein encoded by the segment S4, has been reported for its single-stranded RNA (ssRNA) binding activity, and it is divided into diverse lineages that conserved by host origin of ARVs [10, 11]; as well it has been used for diagnostic analysis [10, 12]

Methods

Results

Conclusion