New haemorrhagic fever vaccine
Recently a massive outbreak of Ebola swept across West Africa, with cases making it as far as The US and the UK. Ebola is a haemorrhagic fever, meaning it causes massive bleeding in people struck down with it. It’s part of a family of diseases, that came to us from animals like bats, and includes Ebola virus, Marburg virus and Lassa fever. Since these diseases often occur in the same place, and it’s hard to tell which one is which, vaccinating against them can be difficult. That’s why a team at Cambridge University are developing a vaccine that will work against all three. Ruby Osborn visited Jonathan Heeney, Professor of Comparative Pathology at the Veterinary School in Cambridge, to learn about the work they’ve done...
Jonathan - What we’ve done is develop some new technology that allows us to present the immune system with targets - the Achilles Heel - of these viruses. Our approach is to take these synthetic genes we’ve identified, that mimic viral proteins, and put them into a virus that we know is safe for humans. In that way, it replicates and our immune system is triggered to really start to focus on these proteins by this non-disease causing viral vector.
What we use is a vaccine that was used to eliminate smallpox, and we’re able to insert these synthetic genes into the backbone of a smallpox vaccine.
Ruby - So you take this safe version of smallpox and then you make it present ebola proteins to the immune system but it doesn’t actually cause the symptoms of ebola.
Jonathan - That’s exactly right. In fact what it does is trigger the immune system to recognise these proteins in the event that the body comes in contact with the real virus.
Ruby - How for into the development of this vaccine are you?
Jonathan - We’ve done significant tests in animals, don’t forget these viruses are naturally carried by bats and other types of animals in the forest. We use laboratory animals, to make sure that these vaccines are completely safe, before we get the green light to go ahead and evaluate them in humans.
The next step, of course, is then to be able to test them in humans to make sure they’re safe. We’re now at that stage, and we hope by next summer, to be able to start evaluating and testing this in volunteers in England.
Ruby - So I guess you can test that the vaccine doesn’t cause side-effects by just giving it to healthy people but how do you test that it actually gives immunity? I’m assuming you don’t give people ebola and see what happens?
Jonathan - No we don’t. But that’s why laboratory animals are absolutely essential. And without laboratory animals we wouldn’t have vaccines. So these animals have been shown to be protected against ebola and Lassa fever.
Ruby - You mentioned that the viruses are also in animals. Does that make it more difficult to control them than diseases that are just in humans?
Jonathan - Absolutely. It is very difficult to go out and remove bat populations or the wildlife that carry these. These wildlife are really very common and widely dispersed in West Africa. Hence it’s really almost infeasible to exterminate the disease in these animals.
Ruby - Does that mean that we’re not going to eradicate ebola in the same way that we have done with smallpox?
Jonathan - It’s going to be very, very difficult, because there’s a natural reservoir. So really the only best way to deal with this is to vaccinate the populations that are at highest risk.
Ruby - And the huge ebola epidemic we had a few years ago, do we know why it suddenly flared up when it did?
Jonathan - Because it got into the large population centres, in a place where people had never been exposed before. So they had no prior immunological knowledge. Normally, ebola flares up in the rainforests of the Democratic Republic of the Congo, and these are small isolated villages. So they can be, if you like, quarantined. And as long as people don’t leave those areas while they’re alive, the disease usually burns itself out.
Now fortunately in the last 20 or 30 years, we’re aware of these epidemics, and there are specially trained healthcare workers that can go out there with all the protective equipment, and mobile labs and mobile hospitals and be able to help save lives.
Ruby - You’re also working on a project to predict outbreaks and the likely strains that are going to be involved, how do you do that?
Jonathan - So we’re funded be the British government now, to go into these endemic areas, and trap rodents and other wildlife, and to be able to take samples, to see what they are carrying. Not just the viruses that have affected humans, but to see what else is out there, that has the potential to spill over into humans, we sequence these, we accumulate large databases, that will inform us about potential threats., that are forthcoming in the future.
Ruby - And then will you be tweaking the vaccine to try and cover those predicted future problems as well?
Jonathan - That’s exactly right. We’ll take this information, and make sure that our vaccines are future proofed, for future spillovers into humans. This is something that hasn’t been done before.