Molecular detection of avian hepatitis E virus (Orthohepevirus B) in chickens, ducks, geese, and western capercaillies in Poland

Abstract

Orthohepevirus B, commonly known as avian hepatitis E virus (aHEV), causes big liver and spleen disease (BLS) or hepatitis-splenomegaly syndrome (HSS) in chickens. BLS is an emerging disease among chicken flocks in several countries around the world. In our previous studies, serology and molecular biology screening revealed that chicken flocks are widely affected by aHEV in Poland. The present study, which was conducted between 2019 and 2020, aimed to investigate the prevalence of aHEV in chicken flocks and other poultry, including ducks, geese, and turkeys. A total of 307 flocks were examined. In addition, 29 samples from captive wild birds (western capercaillies, Tetrao urogallus) were analyzed. In all the investigated poultry species, except turkeys, the nucleic acid sequence covering part of the ORF1 gene of the aHEV genome was detected (34/336 samples, 10.1%). The infection rate was found to be the highest in broiler breeder chicken flocks (14/40 samples; 35%). Phylogenetic analysis of partial ORF1 gene, which encodes helicase, revealed that the obtained sequences belonged to genotypes 2 and 4, while one belonged to genotype 3. Genotype 2 was detected for the first time in domestic geese and ducks, and genotype 4 was detected for the first time in Poland. The study demonstrated the presence of aHEV among the investigated western capercaillies, suggesting that this species is susceptible to aHEV infections and biosecurity is therefore required in western capercaillie breeding facilities.

A novel genotype of avian hepatitis E virus identified in chickens and common pheasants (Phasianus colchicus), extending its host range

“…Nevertheless, this is the first time that aHEV is reported in common pheasants ( Phasianus colchicus ), extending its natural host range. Such finding, however, is not unexpected as in the last 6 years different studies identified aHEVs in birds other than chickens, demonstrating a much broader natural host range for aHEV than previously considered 10 , 11 , 29 , 30 .…”

“…Previously, aHEV genotypes 2, 3, and 4 were identified in birds in Poland, revealing that aHEV is widely spread in Polish chicken flocks 11 , 31 – 33 . Interestingly, some aHEV partial helicase sequences recently reported from broilers and laying hens in Poland, which were assigned to genotype 4 11 , seem to be phylogenetically related to the aHEV genomes reported in the present study. Applying the BLAST search algorithm with newly identified genomes, recognized the above-mentioned genotype 4 isolates as sequences with high nucleotide identity (98.2–99.7%).…”

“…Avian HEV has been reported in many countries worldwide, with seroprevalence studies in the USA, Spain, and Nigeria revealing 71–90% of chicken flocks and 15–80% of chickens positive for anti-aHEV antibodies 6 – 9 . Additionally, aHEV infection has been reported in wild birds 10 , 11 and can be experimentally transmitted to turkeys 12 . Due to limitations in growing and isolating aHEV in vitro, the detection of aHEV is based on viral RNA detection by conventional reverse transcriptase polymerase chain reaction (RT-PCR), and antibodies by ELISA 2 .…”

Rat hepatitis E virus (HEV) cross-species infection and transmission in pigs

“…Hepatitis E is a disease caused by hepatitis E virus (HEV) (1). HEV is a widespread pathogen found in wild animals (boar, deer) (2,3), domestic pigs (4,5), rats (6,7), chickens (8,9), and humans (10,11). The disease in humans is mostly defined as self-limiting but can be lethal in people with underlying health conditions (12,13), immunosuppressed (14,15), and during pregnancy (16)(17)(18)(19).…”