Identification of a Putative Novel Genotype of Avian Hepatitis E Virus from Apparently Healthy Chickens in Southwestern Nigeria.

Fisayo Temilade Osamudiamen,Claus-Thomas Bock,Olusola Aanuoluwapo Akanbi,Steffen Zander,Patrycja Klink,Daniel Oladimeji Oluwayelu

doi:10.3390/v13060954

Fisayo Temilade Osamudiamen, Claus-Thomas Bock + Show 4 more

Open Access

https://doi.org/10.3390/v13060954

Copy DOI

Journal: Viruses	Publication Date: May 21, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: University of Ibadan, Robert Koch Institute

Abstract

Avian hepatitis E virus (aHEV) is the major etiological agent of hepatitis-splenomegaly syndrome (HSS), big liver and spleen disease (BLSD), and hepatic rupture hemorrhage syndrome (HRHS) in chickens. Infections with aHEV cause a significant decrease in egg production and increased mortality in chickens worldwide. However, studies on the prevalence of aHEV in Nigeria are scarce. In this study, serum (n = 88) and fecal samples (n = 110) obtained from apparently healthy layer chickens from three states in southwestern Nigeria were analyzed by nested reverse transcription-polymerase chain reaction (nRT-PCR) targeting the helicase and capsid gene for the presence of aHEV. Avian HEV was detected in 12.5% (n = 11/88) of serum samples and 9.1% (n = 10/110) of fecal samples tested. Phylogenetic analysis showed that five of the twelve identified aHEV sequences belonged to genotype 2. The remaining seven sequences were only distantly related to other known aHEV isolates. After amplification of the near-complete ORF2 fragment (1618 bp) and part of the ORF1 (582 bp) of isolate YF40_aHEV_NG phylogenetic analysis revealed a nucleotide sequence identity between 79.0 and 82.6% and 80.1 and 83.5%, respectively, to other known aHEV strains, indicating that the Nigerian isolate YF40_aHEV_NG belongs to a novel aHEV genotype. This is the first report of co-circulation of aHEV genotypes in chickens in Nigeria.

Highlights

Avian hepatitis E virus is a single-stranded, non-enveloped, positive senseRNA virus belonging to the family Hepeviridae, genus Orthohepevirus and Orthohepevirus B species
The whole genome of Avian hepatitis E virus (aHEV) is approximately 6.7 kb in length and consists of a 5 non-coding region of about 25 bp, followed by three unique open reading frames (ORF1-3), and a 3 non-coding region with a polyadenylated tail [1,2]. It is considered as a causative agent of hepatitis-splenomegaly syndrome (HSS) and big liver and spleen disease (BLSD) in chickens, turkeys, and wild birds, and the recently reported hepatic rupture hemorrhage syndrome (HRHS) in chickens [3,4,5,6,7]
Our findings suggest a natural, subclinical infection of commercial layer chicken flocks with aHEV in Ogun, Osun, and Oyo states, southwest Nigeria, since during the time of sampling the chickens showed no obvious signs of disease and, in each state, at least one sample was positive for aHEV RNA

Summary

Introduction

Avian hepatitis E virus (aHEV) is a single-stranded, non-enveloped, positive senseRNA virus belonging to the family Hepeviridae, genus Orthohepevirus and Orthohepevirus B species. The whole genome of aHEV is approximately 6.7 kb in length and consists of a 5 non-coding region of about 25 bp, followed by three unique open reading frames (ORF1-3), and a 3 non-coding region with a polyadenylated tail [1,2]. It is considered as a causative agent of hepatitis-splenomegaly syndrome (HSS) and big liver and spleen disease (BLSD) in chickens, turkeys, and wild birds, and the recently reported hepatic rupture hemorrhage syndrome (HRHS) in chickens [3,4,5,6,7]. It has been demonstrated that both aHEV RNA and anti-aHEV antibodies can be recovered from healthy chicken flocks [14]

Methods

Results

Discussion

Conclusion