THE Pirbright Institute has developed a new vaccine that generates a faster and stronger immune response in chickens against the H9N2 avian influenza (AI) strain, compared to the current standard inactivated virus vaccine.

Birds given the new vaccine produced antibody responses as early as six days after inoculation. 

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They shed significantly less flu virus when challenged with a natural flu strain, indicating the birds would be less likely to spread infection. 

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, called Antigen Presenting Cells (APCs), to efficiently capture and process the tagged proteins for triggering an immune response.

Effective vaccine

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, this vaccine will 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.

Large-scale manufacture

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, Pirbright said.

 Professor 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 amongst vaccinated birds, which is essential for protecting poultry welfare, increasing food production, and reducing the risk of avian influenza spreading to humans.”

The results were published in npj Vaccines and is titled: Selectively Targeting Haemagglutinin Antigen to Chicken CD83 Receptor Induces Faster and Stronger Immunity against Avian Influenza’