Improved poultry influenza vaccine provides rapid protection

A vaccine developed by researchers at The Pirbright Institute triggers a rapid immune response which protects chickens against signs of disease and reduces virus shedding. The researchers say the vaccine would also be easier and less costly to produce than the traditional influenza vaccines made in chicken eggs.

Many poultry influenza vaccines protect birds from serious illness and death, but do not prevent them from transmitting the virus. In recent years, new methods have been developed to enhance the immune responses that vaccines produce and reduce the amount of virus shed by birds into the environment.

One of these techniques involves tagging influenza virus proteins with a marker that makes them easier for antigen presenting cells (APCs) to capture. These immune cells can efficiently process the tagged proteins resulting in robust and long-lasting antiviral responses in chickens.

The Pirbright researchers have shown that tagging the influenza virus haemagglutinin (HA) protein and directing it to target a specific protein on the chicken APCs – CD83 – generates faster and stronger immune responses against H9N2 avian influenza virus compared to the current industry standard inactivated virus vaccine.

The results published in npj Vaccines revealed that the vaccine was both fast acting and effective. Birds produced antibody responses as early as six days after vaccination and they shed significantly less virus when challenged with a natural influenza 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.

As well as providing enhanced protection, this vaccine will be easier and less costly to manufacture. The tagged influenza virus HA protein can be produced in a laboratory culture of insect cells instead of using eggs to grow live vaccine viruses. This would enable the poultry industry to reduce its reliance on chicken eggs for vaccine production.

As the new vaccine does not contain live influenza 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. The Pirbright team is currently investigating the vaccine’s potential for commercial production and use in the field.

Article: Shrestha, A., Sadeyen, J. R., Lukosaityte, D., Chang, P., Smith, A., Van Hulten, M., Iqbal, M. (2021). Selectively targeting haemagglutinin antigen to chicken CD83 receptor induces faster and stronger immunity against avian influenza. NPJ Vaccines, 6(1), 90, doi: 10.1038/s41541-021-00350-3