Oral badger vaccine field trial under way
A field trial is under way in Ireland aimed at developing an oral TB badger vaccine, scientists have revealed.
Government agencies, including DEFRA, FERA and the AHVLA, are working together with researchers in the Republic of Ireland and New Zealand to develop an oral vaccine.
The key areas of work include formulation and bait development, efficacy and safety studies and field deployment studies aimed at producing data to submit an application for a licensed product.
Glyn Hewinson, chief scientist at the Animal Health and Veterinary Laboratories Agency (AHVLA), said: “We have been doing some of the experimental studies.
“They [Ireland] are doing a field trial that will give proof of principle that oral vaccination in the field might be possible.
“This is linked in with New Zealand, because the formulations that are being used have been developed for possums in New Zealand.”
At the moment, scientists in the Republic of Ireland are not trialling the vaccine in a bait.
The trial involves trapping badgers, anaesthetising and injecting them so that they swallow the BCG (Mycobacterium bovis bacille Calmette-Guérin) vaccine in a formulation.
“Although it will give you proof of principle over how the vaccine might work in that formulation, it’s not telling you how effective it will be in a bait,” said Prof Hewinson. “There is progress, but these things take a lot of time.”
Some lead candidates that have given proof of principle studies that oral vaccination can give you similar protection to injectable vaccination, he added.
“A number of formulations are under investigation. None of them are ready for use yet.”
Prof Hewinson said there were technical challenges of getting uptake to the different badger populations. There are two challenges – to get the right deployment strategy with the right bait and the right oral vaccine.
“Cubs seem to be slightly easier than adult uptake in terms of the formulations we have got at the moment,” he said.
The efficacy of a vaccination with oral vaccination depends not just how well it works in the individual animal, but how much population coverage you can get, he added.
Compared to an injectable BCG vaccine, oral vaccination is harder to control the dose to get to the right place to give you the right protection, he pointed out.
Prof Hewinson said vaccinating both cows and badgers would significantly reduce TB further than just using cattle vaccines by creating an increased level of immunity within that population.
He added: “Theoretically, can you get herd immunity? I don’t know. The logistics are very difficult. However, the modelling suggests that this would take many, many years to achieve.”
“The time it takes for a vaccine to start having an effect in a wildlife population is dependent on the infected badgers dying off. Any vaccination strategy focusing on badgers would need to be wide-scale and long-term.”
Glyn Hewinson, AHVLA chief scientist
However, Prof Hewinson said research suggests that you have to bear down on the disease in wildlife to stop the spread of disease more effectively.
“The lessons are that if you do nothing about your wildlife reservoir, then you will get spill back into cattle.”
Prof Hewinson said vaccination would “not be a quick fix” and was “no silver bullet” to eradicating bovine TB.
“When you are vaccinating badgers, you are leaving infected animals, so the vaccine doesn’t cure pre-existing infections,” he explained.
“The time it takes for a vaccine to start having an effect in a wildlife population is dependent on the infected badgers dying off. Any vaccination strategy focusing on badgers would need to be wide-scale and long-term.”
He was speaking during an Environment, Food and Rural Affairs (EFRA) committee meeting on bovine TB vaccination on Wednesday (6 March).
According to DEFRA, an oral badger vaccine “may be a more practical option in terms of field deployment, but it is “at the research stage and is still several years away”.
“It may also be a cheaper alternative, although this is not currently clear without a final product, so cannot be guaranteed,” DEFRA said.
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