15 Jul 2021
Institute states vaccine generates faster and stronger immune response, and is less costly to produce.
Paul Imrie
Job Title
Researchers at The Pirbright Institute have developed a new vaccine against H9N2 avian flu that generates a faster and stronger immune response in chickens compared to inactivated virus vaccine.
Using a new vaccination technique to enhance immune responses in birds and reduce the amount of virus shed into the environment, Pirbright said the vaccine would protect birds from serious illness and death as current vaccines do, but also prevent transmission and spread through flocks.
Results on the vaccine have been published in npj Vaccines, and reveal it is fast-acting and effective. Birds produced antibody responses as early as six days after vaccination and shed significantly less flu virus when challenged with a natural flu strain.
High levels of protective antibodies were produced even when birds were given a reduced dose.
The vaccine works by tagging flu virus proteins with a marker that makes it easier for immune cells (antigen-presenting cells [APCs]) to efficiently capture and process the tagged proteins for triggering an immune response.
The team specifically tagged the flu virus haemagglutinin (HA) protein and directed it to target CD83, a protein on the chicken APCs, showing for the first time that this can be used as an effective vaccine.
As well as providing enhanced protection, Pirbright said the vaccine would be easier and less costly to manufacture. The tagged flu virus HA protein can be produced in a laboratory culture of insect cells instead of using eggs to grow live vaccine viruses.
This will allow the poultry industry to reduce its reliance on chicken eggs for vaccine production, increasing the availability of eggs for use as a food source.
As the new vaccine does not contain live flu virus, biosafety risks are reduced, and no specialist high containment facilities would be required for production. These qualities make the vaccine very attractive for large-scale manufacture.
Munir Iqbal, head of Pirbright’s avian influenza virus group, said: “By targeting HA to chicken immune cells, we have generated a powerful addition to the armoury of poultry vaccines.
“Our improved vaccine could help prevent the spread of flu among vaccinated birds, which is essential for protecting poultry welfare, increasing food production and reducing the risk of avian influenza spreading to humans.”
The Pirbright team is currently investigating the vaccine’s potential for commercial production and use in the field. The paper, “Selectively targeting haemagglutinin antigen to chicken CD83 receptor induces faster and stronger immunity against avian influenza”, is available in npj Vaccines.
