Pathogenicity of the Canadian Delmarva (DMV/1639) Infectious Bronchitis Virus (IBV) on Female Reproductive Tract of Chickens.

Mohamed S. H. Hassan,Ahmed Ali,Mohamed Faizal Abdul-Careem,Dayna Goldsmith,Frank van der Meer,Susan C. Cork,Martine Boulianne,Sabrina M. Buharideen,Carla S. Coffin

doi:10.3390/v13122488

Mohamed S. H. Hassan, Ahmed Ali + Show 7 more

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https://doi.org/10.3390/v13122488

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Abstract

Infectious bronchitis virus (IBV) infection causes significant economic losses to various sectors of the poultry industry worldwide. Over the past few years, the incidence of false layer syndrome in Eastern Canadian layer flocks has been associated with the increased prevalence of the IBV Delmarva (DMV)/1639 strain. In this study, 1-day-old specific-pathogen-free (SPF) hens were infected with the Canadian DMV/1639 strain and observed until 16 weeks of age in order to determine if the IBV DMV/1639 strain is causing false layer syndrome. Early after infection, the virus showed a wide tissue distribution with characteristic gross and histopathological lesions in the respiratory tract and kidney. Around 60–70% of the infected hens demonstrated continuous cloacal viral shedding until the end of the experiment (at 16 weeks) which was associated with high IBV genome loads detected in the cecal tonsils. The experiment confirmed the field observations that the Canadian DMV/1639 strain is highly pathogenic to the female reproductive tract causing marked cystic lesions in the oviduct. Moreover, significant histopathological damage was observed in the ovary. Our study provides a detailed description of the pathological consequences of the IBV DMV/1639 strain circulating in an important poultry production sector.

Highlights

Infectious bronchitis (IB) is currently endemic and poses an economic threat to most countries with large-scale poultry production [1,2]
Canada in recent years [30,31], which has been correlated to cystic oviduct and other repro
Canada in recent years [30,31], which has been correlated to cystic oviduct and other reductive tract anomalies observed in the field [32,33]

Summary

Introduction

Infectious bronchitis (IB) is currently endemic and poses an economic threat to most countries with large-scale poultry production [1,2]. The causative agent, infectious bronchitis virus (IBV), is a gammacoronavirus of the family Coronaviridae. IBV is primarily a respiratory pathogen where initial infection and replication occur within the epithelial layer of the upper respiratory tract of chickens causing signs such as gasping, coughing, sneezing, tracheal rales, and nasal discharge [3]. Infected chickens usually develop serous, catarrhal, or caseous exudate covering the thickened mucosa of the trachea, nasal passages, and sinuses. IBV targets lung macrophages [5] and monocytes [6] and is believed to spread beyond the respiratory tract via lymph and/or blood [7]. In addition to the respiratory form of the disease, IBV infection is associated with renal, reproductive, and gastrointestinal pathologies depending on the infecting IBV strain [8]. The emergence of genetically diverse IBV strains is associated with rapid mutation rates, viral recombination, and selection processes [9,10]

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