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Updated: Jul 24, 2026
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Influenza Virus Propagation in Embryonated Chicken Eggs
Published on: March 19, 2015
Nephropathogenic infectious bronchitis in Pennsylvania chickens 1997-2000
A F Ziegler1, B S Ladman, P A Dunn
1Laboratory of Avian Medicine and Pathology, University of Pennsylvania, New Bolton Center, Kennett Square, PA 19348, USA.
Avian Diseases
|December 24, 2002
Summary
Nephropathogenic infectious bronchitis (NIB) caused significant mortality in vaccinated chickens. Two novel IBV genotypes, PA/Wolgemuth/98 and PA/171/99, were identified as the cause of this outbreak.
Area of Science:
- Veterinary Pathology
- Avian Virology
- Poultry Disease Epidemiology
Background:
- Nephropathogenic infectious bronchitis (NIB) outbreaks can cause substantial economic losses in commercial poultry.
- Vaccination against infectious bronchitis virus (IBV) is common, but novel strains can emerge.
- Understanding the genetic diversity and evolution of IBV is crucial for disease control.
Purpose of the Study:
- To diagnose and characterize NIB outbreaks in vaccinated chicken flocks.
- To identify the specific IBV genotypes responsible for the NIB cases.
- To investigate the genetic relationship of the outbreak strains to existing IBV strains.
Main Methods:
- Clinical case investigation and post-mortem examinations.
- Histopathological analysis of affected renal tissues.
- Immunohistochemical staining for IBV antigen detection.
- Virus isolation and sequencing of the IBV S1 subunit gene.
Main Results:
- NIB was diagnosed in 28 vaccinated flocks, with high mortality in broilers (up to 23%) and egg production decline in layers.
- Renal swelling, urate accumulation, and interstitial nephritis were common findings.
- Two unique IBV genotypes, PA/Wolgemuth/98 and PA/171/99, were identified and unrelated to endemic strains.
- PA/Wolgemuth/98 dominated the early outbreak, replaced by PA/171/99 later.
Conclusions:
- The NIB outbreak was caused by two novel and distinct IBV genotypes.
- These genotypes emerged despite vaccination programs, highlighting the need for continuous surveillance.
- The sequential replacement of genotypes suggests viral evolution and adaptation within the poultry population.
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