The team compared IBV genomes that had been passaged through eggs over 100 times to find out which genes are involved in weakening the virus. They discovered that mutations occurred throughout the IBV genomes, but only 9 mutations were found more than once across the viruses.
"This suggests that using eggs as a means of generating infectious bronchitis reductions vaccines can lead to unpredictable change," said Erica Bickerton, Head of the Coronavirus group at Pirbright Institute.
The presence of so few consistent mutations that may weaken the virus indicates the risk that a vaccine strain generated this way could revert back to a more virulent form in the field-She added.
Eventually, the team published the results of the study believes that this genetic change must be fully assured.
Around 44 billion chickens are produced worldwide every year, and as a heavily relied upon food source, it is important that diseases such as IB are controlled effectively. It has been estimated that every 10% reduction in IBV would be worth around £654 million to the global poultry industry.