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Nephropathogenicity of infectious bronchitis virus
Poultry Science
|December 1, 1984
Summary
Infectious bronchitis virus (IBV) strains varied in kidney damage potential in chickens, with Australian and Italian strains being most severe. Age influenced pathogenicity, and some IBV vaccines showed limited protection, with one vaccine strain causing nephritis.
Area of Science:
- Veterinary Virology
- Poultry Pathology
- Immunology
Background:
- Infectious bronchitis virus (IBV) is a significant respiratory pathogen in chickens.
- Nephropathogenicity of IBV strains varies, impacting flock health and economic outcomes.
- Understanding strain-specific pathogenicity is crucial for effective disease control and vaccine development.
Purpose of the Study:
- To compare the nephropathogenicity of four IBV strains from different geographical origins (US, Australia, Italy) in chickens.
- To evaluate the influence of chicken age on IBV pathogenicity and nephritis development.
- To assess the protective efficacy of Massachusetts and Connecticut IBV vaccines against homologous and heterologous challenges.
Main Methods:
- Four IBV strains were inoculated into chickens of different ages.
- Nephropathogenicity was assessed through gross examination and histological studies of kidney damage.
- Virus neutralization assays were performed to determine serological relationships between strains.
- Vaccine efficacy was evaluated by challenging vaccinated chickens with IBV strains.
Main Results:
- The Australian IBV strain was the most nephropathogenic, followed by the Italian and then the two US strains.
- Older chickens exhibited a decreased pathogenic effect from IBV strains.
- Kidney damage (nephritis) was more accurately detected via histology than gross examination.
- Massachusetts and Connecticut IBV vaccines provided inconsistent protection against challenge strains.
- One Massachusetts-type vaccine strain (Holland IBV) induced nephritis, particularly at lower embryo passages.
Conclusions:
- Significant variation exists in the nephropathogenic potential among IBV strains.
- Chicken age is a factor influencing the severity of IBV-induced nephritis.
- Current IBV vaccines may offer limited cross-protection, and some vaccine strains possess nephropathogenic potential.
- Histological examination is superior to gross pathology for diagnosing IBV-induced nephritis.