Ebola drug could also fight norovirus
Known as the winter vomiting bug, many of us may be familiar with this pesky pathogen that leads to millions of people being locked to lavatory seats for longer than they'd like every year.
Currently there is no way to treat it, but now Professor Ian Goodfellow from the University of Cambridge has been investigating a drug called 'Favipiravir', which is more normally used to treat flu but which may have potential applications for norovirus and even Ebola. The drug causes the virus to mutate itself to death. He spoke to Chris Smith about the research...
Ian - Norovirus is probably the most common cause of gastroenteritis in the UK. It's a stomach bug and it causes vomiting and diarrhoea. It infects individuals through the faecal-oral route, or through aerosolised vomit.
Chris - Why is there currently no treatment or no vaccine for it?
Ian - Human noroviruses, we cannot grow them in the laboratory. So, it makes it very, very difficult to understand the biology of these viruses and that's probably the main reason we don't have vaccines or antivirals as yet.
Chris - ...and in this new study, you think that you may have a drug here which will prevent people getting noro in the first place or cut down the period of time that they're suffering with it and so on?
Ian - The main benefit of having this drug would be to treat people who are chronically infected. So, there are certain number of individuals in the population who are immunocompromised. So, they may be undergoing treatment for cancer and this means that they can get norovirus infection for months or even years. It's particularly that cohort of patients with this drug will be of particular use.
Chris - What did you do in order to investigate its action?
Ian - So, we have a mouse model of norovirus infection, of persistent norovirus infection where mice get an infection in their intestines over many, many months and we treated a number of animals with this drug. We're able to show that in some cases, it was able to clear the drug and lead to the animals reduce shedding a virus from one animal to another as well.
Chris - Do we know how it does that?
Ian - The way the drug actually works is by introducing so many mutations into the viral genome that the viral genome no longer functions properly. So, the virus is effectively mutating itself to death.
Chris - How do you make sure that that only happens to the virus and not one of our own cells because the same thing, if you mutate our own cells, we get cancer?
Ian - That's true. So, the drug itself is a class of molecules, which are known as nucleoside analogues. So effectively, it looks very similar to the building blocks of the viral genome and this is RNA. It's specifically copied into the viral genome only by an enzyme that the virus makes. So, it isn't incorporated into our cellular DNA or our RNA for example.
Chris - The idea being then that you end up with the viruses that are in the body are just not viable anymore. Where would that be useful in helping the individual who takes it or could it be used for say, controlling onward spread of the virus?
Ian - One of the other areas we think this type of drug might be of use is where you've got an environment where it's difficult to move individuals. So particularly, in old people's homes, so you wouldn't necessarily treat the infected individual but you would treat all the healthcare workers. You might come in contact with them and in all individuals you might share a common space. That's where we think it will have a real impact as well.
Chris - Briefly, we mentioned at the beginning that this may also work for Ebola. Why do we think that?
Ian - Well, it works against any virus in cell culture whose genome is made up of RNA and there's some very nice studies also performed in mice that showed that the drug will also work cure infection in mice. It's actually been used to treat some of the patients that have been infected with Ebola in the ongoing outbreak.