Science - March 9, 2006

Spray for chicken vaccine

Wageningen UR has received approximately 1.1 million euros from the ministry of agriculture for research on new vaccines against bird flu. The money will be used to investigate whether it is possible to vaccinate chickens using an atomiser, and the extent to which vaccinated poultry can still pass on the virus.

‘We want to develop a marker vaccine that can be used as widely as possible. I can’t go into further details in case patenting is involved,’ says virologist Dr Wim van der Poel of the Animal Sciences Group. The researchers want to develop a vaccine that can be administered using an atomiser spray, so that large flocks of poultry inhale the vaccine. ‘This was one of the requests of the ministry,’ tells Van der Poel. At present the chickens have to be injected individually, a time-consuming, difficult and expensive procedure, especially if vaccination has to be done during an outbreak.

In addition, researchers will examine the variation in the different strains of avian influenza, which vaccines work against the strains and how to distinguish between vaccinated and infected birds on farms, explains Van der Poel’s epidemiologist colleague Professor Mart de Jong. At present an H5N2 vaccine is being used against the current H5N1 virus strain. ‘We have the impression that it is working well, but there is more genetic diversity in the virus than just the different N-types within one H-type. We want to map this diversity.’

Another research topic is the question of the strength of the immunity of vaccinated poultry. This can be examined by placing vaccinated chickens with unvaccinated chickens and vice versa. The more chickens that are vaccinated, the smaller the chance of an outbreak. ‘We call this the herd community,’ says De Jong. ‘It’s the same as when you were a child and protected against the measles because everyone else was vaccinated, rather than because you yourself had been vaccinated.’

Van der Poel expects even more money for vaccine research in the next few years. ‘It is certainly not the case that we will be able to come up with a vaccine within a year. Developing a vaccine takes much longer because it involves a lot of laboratory work first and then at a later stage animal experiments. At present we are still building up expertise. We have already worked on influenza viruses, but not yet on such a big scale.’ / MW

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