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  • Writer's picturePatrick Dawkins

New AFB Vaccine, But Not for NZ

Approval of an American foulbrood (AFB) vaccine in the USA in January has given beekeepers there another option in protecting honey bee colonies against the disease. Dalan Animal Health have been granted a conditional licence to use the vaccine by the US Department of Agriculture, but rules around treating AFB are very different in America to that of New Zealand. So, is this vaccination advancement any benefit to Kiwi beekeepers?

Increased field trials likely await, following approval of Dalan’s vaccine, which relies on trans-generational immune priming using the bacteria that causes AFB – paenibacillus larvae. That means the vaccine can be incorporated into ‘queen candy’, which is fed to queen bees. Once ingested, fragments of the vaccine are deposited in the queen’s ovaries. Having been exposed to the vaccine, the developing larvae have immunity as they hatch.

Dalan Animal Health have gained a conditional licence to use their Paenibacillus larvae bacterin vaccine against AFB in honey bee colonies in the USA, which will likely see field trials taking place.

America has long tackled AFB infection by use of antibiotics to infected colonies, whereas the new vaccine method would allow treatment prior to infection. The method of using P. larvae bacterium was shown to reduce larvae death by 30-50% in a study carried out by Dalan and which was critical to gaining approval (The oral vaccination with Paenibacillus larvae bacterin can decrease susceptibility to American Foulbrood infection in honey bees—A safety and efficacy study).

However, in New Zealand the use of drugs to treat AFB is outlawed under clause 14 of the Biosecurity (National American Foulbrood Pest Management Plan) Order 1998, as Kiwi beekeepers strive for elimination of the disease from managed colonies. Any use of a vaccine in New Zealand would require an amendment to the Act, as well as registration under the Agricultural Compounds and Veterinary Medicines Act 1997, so is highly unlikely at present.

Nonetheless, AFB Management Agency national compliance manager Clifton King has read the research paper from Dalan and confirms that, at present, it will not be of any use in New Zealand’s management strategy against AFB.

“My interpretation of the data provided is that all challenged beehives still become infected with AFB. The reduction in larval death rates observed will result in longer incubation periods before clinical signs are observed, and vaccinated beehives will be slower to die from AFB. There is considerable uncertainty as to whether the effects of increasing the incubation period and time to hive death will increase or decrease the spread of AFB between beehives,” King says.

While Dalan has made a leap forward in AFB vaccine research with the American approval for use, at Canterbury University Heather Hendrickson’s lab are undertaking their own research into an AFB ‘vaccine’ of sorts, using bacteriophage therapy. She also can’t see the Dalan vaccine conforming with New Zealand’s AFB Pest Management Plan.

“The level of protection offered, 30-50%, is unlikely to mean an entire hive is symptom-free,” Hendrickson points out.

“So, in New Zealand it would be burnt, whereas in the US they can treat with antibiotics. So, I don't think that this vaccination strategy alone would save hives given our eradication efforts, based on this data. It does sound to me like it would extend the period over which a hive would appear to be asymptomatic.”

She also notes there are several different strains of AFB known to be in New Zealand, which could limit effectiveness of the vaccine.

Furthermore, with added importance applied to producing ‘AFB-free’ honey for export to China in recent years, this must be considered when assessing the suitability of a product which voluntarily introduces P. larvae spores to bees.

“There are a lot of spores per bee remaining in the asymptomatic larvae treatments in the lab, with an average of 158 spores per bee according to the research. This would mean that hives and honey could test positive for AFB. That would be a major problem for our export markets,” Hendrickson says.

So, while scientific advancements to combat any disease of honey bees are no doubt welcomed by beekeepers, Dalan’s ‘AFB vaccine’ is unlikely to be in use in New Zealand anytime soon.


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