Vaccine for killer Hendra virus launched

Glen Paul: G’day, and welcome to CSIROpod, I’m Glen Paul. Discovered in 1994, the Hendra virus is recognised as one of the most dangerous virus infections for horses and humans to date, taking the lives of over 60 horses and four people. While the disease remains of major concern, a degree of relief has come to Australian horse owners and the equine industry with the announcement of a horse vaccine.

The new Equivac® HeV horse vaccine is an international collaboration, and a major win for not only horses, but people working in veterinary practice, who are at great risk of Hendra infection. Joining me on the line to discuss the new vaccine is CSIRO’s Doctor Deborah Middleton, who’s been leading the specialist team at the Australian Animal Health Laboratory.

Firstly, Deb, congratulations to you and all concerned on a job well done.

Dr. Middleton: Oh, thank you, Glen, but it’s, as you say, it’s very much a team effort, and it’s the result of probably over 15 years of consolidated work to develop this vaccine.

Glen Paul: Hmm. So how did it make you feel then when the vaccine was finally signed off as safe and ready to go?

Dr. Middleton: Well I think I felt relief really, as much as excitement. I’ve been very aware that for many years veterinarians and the people involved in the horse industry haven’t really had any solid tools to protect them against Hendra virus infection from horses, and the equine vaccine represents the first really useful piece of armoury that veterinarians and horse owning people can use to help them prevent Hendra virus infection in their animals, and by extension in themselves.

Glen Paul: Hmm, absolutely. And as you say, it’s been a long time in the making, but what led to the breakthrough?

Dr. Middleton: Well I think it was a combination of events. As you mentioned in your introduction, we have certainly known about Hendra virus infection in horses for, you know, over 15 years now, and we’ve seen repeated outbreaks particularly in coastal Queensland, but extending into northern New South Wales, and I think the key breakthroughs were in developing an understanding at a science level of what parts of the virus were important in establishing infection in horses, and then we were able to do some preliminary studies in the laboratory with an experimental vaccine that led us to develop, you know, a level of confidence that this vaccine could be translated to use in horses.

And then I think the real turning points came with the outbreaks in 2008, 2009, and of course most recently, you know that very serious series of outbreaks in 2011, which really brought the necessary State and Federal Government funding onboard that allowed us to progress the work into horses, which of course were the species of greatest interest to us.

And of course once the State and Federal Government funding support was gained, then you know the commercial partner stepped in, and of course that was the really essential component to delivering a vaccine, you know, in industrial quantities, so large numbers of doses, using highly controlled formulations with potency testing, efficacy testing, and safety testing, to make sure that we had a safe efficacious vaccine on the market.

Glen Paul: Hmm. And how much protection does it offer?

Dr. Middleton: Well we certainly know that, in certainly the animals that we’ve studied, it appears to offer protection against infection with Hendra virus, which means that the horses do not replicate the virus, they do not shed the virus, and they do not become sick with the virus. There is still one key piece of work that we need to do, and that is to develop a better understanding of how often horses might need to receive a booster vaccination, and that work will be ongoing.

Glen Paul: If people then become comfortable with that, what’s the risk of a “she’ll be right” attitude towards Hendra developing?

Dr. Middleton: Oh look, I think that is always a risk. I think that if people think that they are operating under an umbrella of vaccination that is absolutely protective it may lead to a bit of a level of complacency. But, you know, I’d be the first person to say that no vaccine is going to be 100% effective, no vaccine has ever been 100% effective, and this one will be no exception.

But I think that, you know, not all the horse population will be vaccinated, people do need to still be aware of the potential for Hendra virus infection, but I think if they have vaccinated their horses they have dramatically reduced the risk of those horses developing Hendra infection and transmitting it to people who might come in contact with them.

Glen Paul: Do you foresee a time when legislation might be put in place that a horse must be immunised?

Dr. Middleton: I think that, you know, what’s called mandatory vaccination is unlikely to ever come into play, for a number of reasons, not least because we would just not get complete coverage of the horse population in Australia. I mean we do know that we have populations of wild horses that certainly would not be available to be vaccinated.

I think what will happen is that the use of the vaccine will very much be driven by the industry – I suspect that private veterinarians will encourage their clients to have their horses vaccinated; it’s likely that the racing industry, and any groups where horses meet, so three day events, pony club, will insist that horses attending those meetings are vaccinated. So I think that the uptake will be driven by people who are concerned about their own health, people who are concerned about their horse’s health, and industry groups where there would be very profound implications for a Hendra virus outbreak, you know in their particular industry.

Glen Paul: OK. So does this mean we’re coming towards the end of the Hendra story?

Dr. Middleton: Oh, that’s certainly not the end of the Hendra story. We still have questions that we need to answer about Hendra virus infection in dogs; a really big issue I think is what is the status of animals which have recovered from Hendra virus infection, in terms of their ability to develop disease again at a later date; there’s an awful lot we don’t understand about the spill over of Hendra virus from flying-fox populations, and I think that may be the most challenging question to answer from a scientific perspective.

Glen Paul: Hmm. So what sort of spin-offs do you see from the development of this vaccine in combating other diseases?

Dr. Middleton: I mean we already know that this particular vaccine does offer some cross protection against a very closely related virus, Nipah virus, which does not occur in Australia, but is of concern in other parts of the world. I think that in some ways the technology that was used to develop the Hendra virus vaccine is actually comparatively straightforward, and certainly similar vaccine preparations have been produced against a variety of diseases in the past.

I think the really unusual thing about the Hendra vaccine is that to my knowledge it’s the first commercial vaccine for what’s called a Bio-Safety Level-4 disease agent, which are the most dangerous human disease agents in the world, it’s the first Bio-Safety Level-4 vaccine that’s ever been produced.

Glen Paul: Fantastic. And how will it be administered? How do horse owners get their hands on it?

Dr. Middleton: Well it’s going to be administered by Veterinarians, so it’s what’s called a Vet only vaccine. Veterinarians will have to be registered to be able to acquire the vaccine and to administer it. But the vaccine itself is perfectly standard vaccine that’s delivered into the muscle of the horse, so it’s no different in terms of its appearance, or the way it’s given, to any other intramuscular vaccine of horses.

Glen Paul: Well look, it’s a fantastic achievement, Deborah. Not only obviously are you’re going to save the lives of countless horses, but also people, too, so that is just a marvellous thing.

Dr. Middleton: Well thank you, Glen. I mean there have been really, I guess, three key players in the process. There’s been ourselves, CSIRO Australian Animal Health Laboratory, and of course the colleagues at the Henry Jackson Foundation in the U.S., and really the critical turning point was when Pfizer joined the team, so you know Pfizer Animal Health and their experience in vaccine formulations for animals, their proven adjuvants for use in horses have absolutely transformed the time to market for this product.

Glen Paul: Fabulous. Thank you so much for talking to me, Deborah.

Dr. Middleton: No worries, Glen.

Glen Paul: Doctor Deborah Middleton. And to find out more about the research, or to follow us on other social media, visit www.csiro.au.