Faced with recurring outbreaks of Highly Pathogenic Avian Influenza, Wageningen. Bioveterinary Research was commissioned in 2022 to conduct a laboratory trial to confirm the effectiveness of two commercially available HVT H5 avian influenza vaccines. The trial was conducted in collaboration with Utrecht University and Wageningen University and Research Institute. The trial was sponsored by the Dutch Ministry of Agriculture, Nature and Food Quality.
Vectormune® AI, the Ceva product, is based on a turkey herpesvirus expressing the hemagglutinin gene of an H5N1 avian influenza virus as an insert.
The study involving laying hens, presumably free of AI antibody, was completely effective in preventing disease and mortality after challenge with a field strain of HPAI H5N1 virus. The trial also demonstrated that infected hens did not spread virus to non-vaccinated contact hens. The Dutch Ministry of Agriculture has now commissioned a field study to commence within a month to confirm the findings of the controlled laboratory trial.
The vaccines evaluated are DIVA compliant, enabling differentiation between vaccinated and infected flocks based on serology. Under practical conditions, this is considered an obsolete attribute given that diagnosis of avian influenza is now based on antigen detection using either lateral flow immunoassay or PCR technology.
In 2015, the Ceva vaccine was evaluated in a collaborative trial involving research institutes in Italy, the Netherlands, Egypt, Belgium and Indonesia and the U.S. (Southeastern Poultry Research Laboratory, USDA-ARS)*.
Results of the field evaluation demonstrated protection against a range of challenge viruses with respect to protection against mortality and limited virus shedding. The authors concluded that Vectormune® AI vaccine was a “reliable tool to complement biosecurity and sanitary policies for better controlling the disease due to HPAI H5 subtypes when the vaccination is applied as a control measure”.
Millions of doses of Vectormune® AI have been administered in Egypt, Indonesia, Mexico and Eastern Europe nations. Following recent outbreaks, the vaccine is now deployed in South America complementing traditional methods of control.
The results under field conditions will become apparent following the anticipated outbreaks of H5N1 avian influenza now regarded as endemic in many nations. Veterinary health authorities in nations with industrialized poultry industries will be guided in their decisions concerning adoption of vaccination by the results of field trials. Given the inevitability of vaccination over the intermediate term, trade restrictions directed against nations or regions that apply effective vaccines with complementary surveillance will have to be modified. Scientific data and guidance from the World Organization of Animal Health will influence adoption of vaccines as an adjunct to current control methods that do not appear to be effective and have little prospect of achieving eradication.
We cannot continue to absolutely exclude vaccination against HPAI as a possible measure to contain and control HPAI. Given that the infection is now de facto seasonally and regionally endemic in the U.S. and in all probability is transmitted over short distances by the aerogenous route vaccination should be considered for limited application for breeders, laying flocks, growing turkeys raised in high risk areas.
Avian influenza should be regarded as the “Newcastle disease of the 2020s”. This equally catastrophic infection was a major restraint to production and profitability during the 1970s, but is effectively controlled worldwide using a range of vaccines.
*Gardin, Y. et al. Experimental and Field Results Regarding Immunity Induced by Recombinant Turkey Herpesvirus H5 Vector Vaccine Against H5N1 and Other H5 Highly Pathogenic Avian Influenza Virus Challenges. Avian Diseases. 60:232-237 (2016)