Kidney Cell-Adapted Infectious Bronchitis Virus Arkansas Delmarva Poultry Industry Vaccine Confers Effective...

Area of Science:

• Veterinary Virology
• Avian Pathology
• Vaccine Development

Background:

• Commercial infectious bronchitis virus (IBV) Arkansas vaccines can lead to vaccine-derived subpopulations.
• Adaptation of IBV ArkDPI vaccine to chicken embryo kidney (CEK) cells resulted in a more homogeneous virus population.
• Previous studies indicated reduced vaccine-derived subpopulations with CEK-adapted IBV.

Purpose of the Study:

• To evaluate the efficacy and genetic stability of a CEK-adapted IBV ArkDPI-derived vaccine.
• To compare the protective effect of the CEK-adapted IBV vaccine against virulent Ark-type IBV challenge with a commercial vaccine.

Main Methods:

• Chickens were vaccinated with low doses of CEK-adapted IBV vaccine and challenged with virulent IBV.
• Viral RNA loads in lachrymal fluids and tracheal swabs were quantified post-challenge.
• Genetic analysis of IBV spike (S) gene sequences was performed in vaccinated and challenged chickens.
• Protection was assessed by comparing respiratory signs, viral load, and genetic subpopulations.

Main Results:

• Vaccination with CEK-adapted IBV significantly reduced IBV RNA in lachrymal fluids and tracheal swabs.
• All vaccinated groups showed reduced respiratory signs and viral load compared to unvaccinated controls.
• No IBV subpopulations different from the challenge virus were detected in chickens vaccinated with CEK-adapted IBV.
• Conversely, genetic variants of IBV were detected in chickens vaccinated with the commercial Ark vaccine.

Conclusions:

• The CEK-adapted IBV ArkDPI-derived vaccine is a promising candidate for protecting chickens against virulent Ark-type IBV strains.
• This adapted vaccine demonstrates improved genetic homogeneity and efficacy compared to the commercial vaccine.
• CEK cell adaptation offers a strategy to enhance the safety and effectiveness of IBV vaccines.