Identification and characterization of avian hepatitis E virus in 2013 outbreaks of hepatitis-splenomegaly syndrome in two US layer operations

Title
Identification and characterization of avian hepatitis E virus in 2013 outbreaks of hepatitis-splenomegaly syndrome in two US layer operations
Publication Date
2014
Author(s)
Gerber, Priscilla Freitas
( author )
OrcID: https://orcid.org/0000-0002-8343-8299
Email: pgerber2@une.edu.au
UNE Id une-id:pgerber2
Trampel, Darrell W
Opriessnig, Tanja
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Taylor & Francis
Place of publication
United Kingdom
DOI
10.1080/03079457.2014.935755
UNE publication id
une:21456
Abstract
Two commercial Midwestern egg-type chicken flocks experienced significant increases in mortality rates in April 2013 with clinical signs appearing in 17-week-old pullets on Farm A and in 46-week-old hens on Farm B. Average weekly mortality was 0.44% over a 4-week period on Farm A and 0.17% over an 8-week period on Farm B. On Farm A, flocks in the affected house had a 45% decrease in daily egg production from weeks 19 to 27 when compared with standard egg production curves (P < 0.01) while no decrease in egg production was noticed on Farm B. Post-mortem examination revealed changes consistent with hepatitis-splenomegaly syndrome, including hepatomegaly with serosanguineous fluid in the coelomic cavity and hepatic subcapsular haemorrhages. Microscopic lesions were characterized by multifocal necrotizing hepatitis and intrahepatic haemorrhage. No significant bacteria were recovered from liver samples, but 72 to 100% of the liver samples from affected chickens on Farm A (8/11) and Farm B (7/7) contained detectable amounts of avian hepatitis E virus (aHEV) RNA as determined by polymerase chain reaction. Sequencing and phylogenetic analysis of a 361-base-pair fragment of the helicase gene demonstrated 98.6 to 100% nucleotide identity between the aHEV genomes from Farm A and Farm B, whereas identities ranged from 74.6 to 90.5% when compared with other representative sequences. Sequences from this study clustered within aHEV genotype 2 previously recognized in the USA. In contrast to other reported aHEV outbreaks that occurred in 30-week-old to 80-week-old chickens, in the present investigation clinical aHEV was identified in 17-week-old chickens on one of the farms.
Link
Citation
Avian Pathology, 43(4), p. 357-363
ISSN
1465-3338
0307-9457
Start page
357
End page
363

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