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A model for determining immunogenic relationships between avian infectious bronchitis viruses
Y Arvidson1, G A Tannock, A Senthilselvan
1Faculty of Medicine, University of Newcastle, N. S. W., Australia.
Archives of Virology
|January 1, 1990
Summary
A new model reveals infectious bronchitis virus (IBV) strains vary greatly in immunogenicity. Live vaccines administered intratracheally offer superior protection in chickens compared to inactivated vaccines.
Area of Science:
- Veterinary Virology
- Immunology
- Poultry Health
Background:
- Infectious bronchitis virus (IBV) causes significant economic losses in the poultry industry worldwide.
- Understanding the immunogenic relationships between IBV strains is crucial for developing effective vaccines.
- Previous models for assessing IBV immunogenicity have limitations in accurately quantifying strain-specific protection.
Purpose of the Study:
- To develop and validate a quantitative model for assessing immunogenic relationships between infectious bronchitis virus strains.
- To compare the immunogenicity of different administration routes and types of IBV vaccines.
- To investigate the relationship between serotype and protection against challenge in Australian IBV strains.
Main Methods:
- A novel model based on the vaccinating dose required to prevent multiplication of a standard challenge dose of homologous IBV in specific-pathogen-free chickens was established.
- Different vaccinating doses were administered to chickens via various routes (tracheal, ocular, intramuscular).
- Vaccine efficacy was assessed by challenging chickens with homologous IBV strains and measuring viral replication in the lungs.
Main Results:
- The model demonstrated that approximately 100-fold higher vaccinating doses are required for immunity with one dose compared to two doses.
- Significant differences in immunogenicity, exceeding 1,000-fold, were observed between Australian IBV strains.
- Immunogenicity followed the order: live virus (tracheal) > live virus (ocular) > inactivated virus (tracheal) > inactivated virus (intramuscular).
- Protection against challenge in chickens inoculated with Australian vaccine strains was found to be independent of serotype.
Conclusions:
- The developed model provides a robust method for quantifying IBV strain immunogenicity and vaccine efficacy.
- Vaccine administration route and virus type significantly impact the level of protection achieved against IBV.
- Serotype is not a reliable predictor of protection against challenge for Australian IBV vaccine strains, highlighting the need for strain-specific vaccine evaluation.