Pirbright Institute develops new approach to designing poutry vaccines
Scientists used a ‘targeted attenuation’ approach
3 March 2025
2 minute read
By: Infectious bronchitis virus (IBV), also known as avian coronavirus, is one of the poultry industry’s biggest challenges.
This highly contagious virus causes infectious bronchitis, a respiratory disease that impacts both the health and productivity of chickens.
Signs of the disease include snicking, wheezing, watery eyes and nasal discharge. Infection with IBV not only raises welfare concerns, but also results in reduced weight gain and a drop in egg production.
To control IBV, chickens are vaccinated using a combination of live attenuated vaccines and inactivated vaccines. Live attenuated vaccines use a weakened form of the virus and are created by repeatedly ‘growing’ the virus in eggs until it loses virulence.
However, this method is unpredictable, relying on random genetic mutations that sometimes compromise efficacy of the vaccine, according to a press release from Pirbright Institute. Additionally, the process is time-consuming, meaning it’s ill adapted for responding to new or emerging strains of the virus.
This has prompted scientists at Pirbright to explore new ways of developing vaccines that can be adapted across strains and used in response to emerging ones.
In a new study published in the Journal of Virology, they used a ‘targeted attenuation’ approach to make specific modifications to weaken the virus without compromising its ability to stimulate immunity.
Vaccines against other coronaviruses like SARS-CoV-2 primarily target the Spike (S) protein. However, this approach has proven ineffective for IBV, highlighting the need for alternative strategies.
The researchers therefore looked at a different target, the non-structural protein (nsp3), specifically a region within this called the macrodomain. By introducing targeted mutations within this protein, they identified genetic changes that could weaken the virus while maintaining its capacity to induce immunity.
The targets in this study are conserved amongst IBV strains and the coronavirus family offering a potential method of rational attenuation that can be universally applied for vaccine development.
Erica Bickerton, Coronavirus group lead said “By using targeted attenuation we can develop vaccines that are more effective and adaptable to new strains. It also opens up the possibility of developing vaccines against other coronaviruses.”
This approach could help reduce the burden of IBV on the poultry industry, improve welfare and protect food security. It also has broader benefits for the development of coronavirus vaccines in both animal and human health.
