Wageningen is testing three vaccines against bird flu

Wageningen Bioveterinary Research is studying the effect of three bird flu vaccines. “Before vaccines are used in poultry, more information is needed about their efficacy,” explains Nancy Berens, an avian influenza expert at WBVR.

The first vaccine trial will be conducted at the research facilities of the High Containment Unit at WBVR. It is a study being conducted jointly by the University of Utrecht, Wageningen University and Research, Royal GD and the Ministry of Agriculture, Nature and Food Quality.

Vaccines are being tested from three different drug companies. This first experiment, which has already begun, is carried out with groups of ten laying hens. They are vaccinated as one-day-old chicks (with two types of vaccines) or at two weeks of age. When chickens are eight weeks old, half of them are intentionally infected with the bird flu virus. Then the chickens meet again.

symptoms

“Vaccines should protect chickens from symptoms of disease and prevent the spread of the virus,” Berens says. This means that chickens that are not intentionally infected with bird flu must be kept free of field virus and must not get sick. We will have the results at the end of December.

Two of the three vaccines being tested have been announced. Related to Vectormune HVT AIV from Ceva Santé Animale, this vaccine contains a small portion of the bird flu vaccine and can be combined with the Marek vaccine. The vaccine is already on the market in the United States, among other things.

Moreover, a vaccine from Huvepharma that contains part of the genetic code for the bird flu virus, works in the same way as the new Corona vaccines from Pfizer and Moderna. No data was shared for the third vaccine.

Diva Vaccines

All three vaccines contain only parts of the virus, making the vaccinated animals distinct from the field virus of avian influenza. They are called diffa vaccines, which means differentiating between infected and vaccinated animals. Also known as marker vaccines.

According to Berens, working with Diva vaccines is necessary for a number of things. You want to prevent vaccinated poultry from getting infected, not getting sick, but spreading the field type of bird flu virus. To do this, you must be able to distinguish between animals that have only been vaccinated or animals that are also infected with the field virus. In addition, it will be necessary to prevent trade barriers.

field experience

After this first trial, a field trial will follow early next year. Preparations are already underway for this. Safety will be of paramount importance in this field trial. “We may be collecting vaccines to ensure that the animals are really protected and, above all, that the field virus doesn’t spread,” Berens says.

Vaccines will also have to prove in field trial that they prevent symptoms of disease and the spread of the virus. This can occur quite differently in practice than controlled conditions in WBVR. Our animals do not suffer from other germs and do not receive any other vaccines. In practice, this is the case and then vaccination against bird flu can be different.

In addition to the Netherlands, there is experience with ducks in France. This uses a different vaccine that works best on ducks. A trial is underway with turkeys in Italy, using the same vaccine used in the Netherlands. The test designs are well formatted, so that the results will soon be usable across Europe.

extended season

Berens notes that the call for an effective bird flu vaccine is growing high. Previously, our summer was still free of bird flu infection and we had years with only a few outbreaks. Now there were several outbreaks last year and this year the number of outbreaks in Europe is the highest ever. The season did not stop as usual after the departure of the migratory birds.”

The virus was passed on to other bird species that would not normally be infected, such as terns, gulls, and storks. “Outbreaks of these wild birds have occurred again in commercial poultry farms,” ​​she says. This has serious consequences for the poultry sector due to the disinfection of (contaminated) businesses, the ban on transportation and the constant adherence to the cage.

In large parts of the Netherlands, this obligation to keep cages has not been withdrawn since the first cases of bird flu appeared in October 2021. So the Ministry of Agriculture commissioned WBVR in Lelystad, part of Wageningen University and Research, to conduct this study.

Set the instructions

If the trial in WBVR and the field trial went well, it’s not over yet. The European Union will have to adapt guidelines to allow trade in vaccinated poultry. Third countries will also have to accept it.

Furthermore, vaccine manufacturers have to formally apply for registration in the European Union. In general, according to Byrnes, there will be no vaccine available in the 2023-2024 season, perhaps only in the 2024-2024 season.

Biosecurity remains a necessity

Until a vaccine is available, very strict biosecurity will remain key to preventing bird flu. Because there is a lot of interest in the Netherlands and the rapid disinfection of infected farms, the number of outbreaks has remained somewhat limited and much lower than in 2003.

But even if a vaccine is available, biosafety will still be important, according to Berens. “The vaccine never protects 100%. So you should always make sure to prevent bird flu from entering as much as possible.

Leave a Comment