• Vaccinated animals can easily be differentiated from infected animals using already available diagnostics ‘antibody detection’ tests (DIVA compatible).
• The vaccine can be administered as a single dose to day-old chickens. Eliminating the need for repeated immunisations saves time and cost.
• This vaccine can produce higher cross-reactive antibodies against dif- ferent strains of flu.
• In some case, traditional inactivated virus vaccines may carry some residual non-inactivated virus that may initiate infection. This is prevented with the new vaccine. “
What are the implications in the field? “This vaccine will provide robust immunity in vaccinated flocks against specific pathogens, such as avian influenza. This will reduce economic losses, as well as improve the health and welfare of the birds. The vacci- nated birds will also shed significantly smaller amounts of virus when challenged with infectious virus. This reduces virus load in the environ- ment and will result in lower disease incidence in birds, leading to a reduced risk of zoonotic transmission from infected birds to humans.”
Could this new vaccine lower the threshold for use in countries that are now reluctant to use it (e.g. the EU)? “The use of traditional inactivated virus vaccines is prohibited in some countries because these vaccines do not allow differentiation between
vaccinated and infected birds (DIVA). Such DIVA incompatibility of the vaccine can interfere with the disease surveillance system of the coun- try. The new vaccine (TADV) contains only one viral protein (haemag- glutinin) and is compatible with serological tests detecting antibodies against other viral proteins. Thus, this vaccine is compatible with the DIVA strategy which is one of the important requirements for obtain- ing the regulatory approval necessary for the licensing of a poultry avian influenza vaccine in some countries.”
What influenza types are targeted and can the vaccine be adapted to protect against other/new variants? “Yes, as a first step we have produced a prototype targeted vaccine for bird flu (H9N2 virus) which induces strong immunity against the H9N2 virus variants. Our future work will involve producing TADV against a range of different bird flu subtype/serotypes, as well as other poultry pathogens, like the Newcastle disease virus, infectious bursal disease virus and infectious bronchitis virus.”
When will the vaccine reach the market/approval? “We are working jointly with a commercial vaccine producer to take the vaccine from the laboratory into the field. The experimental work and documents required for vaccine regulatory approval are in pro- gress and we anticipate that the vaccine will be available on the market soon.”
The use of a traditional inactivated virus vaccine is prohibited in some countries because these vaccines do not allow differentiation between vaccinated and infected birds (DIVA).
▶ POULTRY WORLD | No. 10, 2021 31
PHOTO: KOOS GROENEWOLD
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