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Cross-Protection by Infectious Bronchitis Viruses Under Controlled Experimental Conditions
H Toro1, V L van Santen1, A M Ghetas1
1Department of Pathobiology, College of Veterinary Medicine, 264 Greene Hall, Auburn University, AL 36849.
Avian Diseases
|December 3, 2015
Summary
Infectious bronchitis virus (IBV) vaccination trials revealed unexpected cross-protection between antigenically distant strains. Prime-boost strategies enhanced protection, highlighting the need for robust controls in IBV vaccine efficacy studies.
Area of Science:
- Veterinary Virology
- Immunology
- Poultry Health
Background:
- Infectious Bronchitis Virus (IBV) poses a significant threat to poultry production worldwide.
- Understanding cross-protection between IBV serotypes is crucial for effective vaccine development.
- Antigenic diversity among IBV strains complicates vaccine strategies.
Purpose of the Study:
- To evaluate the cross-protective efficacy of a Massachusetts (Mass)-type attenuated IBV vaccine against heterologous challenge strains (Arkansas (Ark) and GA13).
- To compare the protective effects of single vaccination versus prime-boost vaccination regimens.
- To emphasize the importance of appropriate control groups in IBV vaccine efficacy trials.
Main Methods:
- Healthy chickens were vaccinated with an attenuated Mass-type IBV vaccine (single or prime-boost).
- Vaccinated chickens were challenged with virulent Ark or GA13 IBV strains.
- Clinical signs, viral load, and histopathological changes were assessed to determine protection levels.
- Spike protein 1 (S1) amino acid identity between vaccine and challenge strains was analyzed.
Main Results:
- Significant cross-protection was observed against antigenically distant IBV strains (76.0–77.3% S1 amino acid identity).
- Prime-boost vaccination with the Mass strain provided better protection against GA13 and improved protection against Ark compared to single vaccination.
- Clinical signs, viral load, and histopathology supported the observed cross-protection.
Conclusions:
- Attenuated IBV vaccines can induce cross-protection against heterologous serotypes, even with considerable antigenic distance.
- Prime-boost vaccination strategies may enhance heterologous protection against IBV.
- Rigorous inclusion of single vaccination and prime-boost control groups is essential for accurately assessing IBV vaccine efficacy against novel or exotic strains.
