Health officials around the world are on alert after the discovery of a new virus in two patients with pneumonia. The agent belongs to the coronavirus group, which includes several common cold viruses but also the virus that causes SARS, a severe disease that killed more than 700 people during a fast-moving global outbreak in 2002 and 2003 before it was contained.
The first known patient in the new incident was a 60-year-old man from Jeddah, Saudi Arabia, who died from pneumonia in July; his case was reported  by Ali Mohamed Zaki of the Soliman Fakeeh Hospital in Jeddah on ProMED, an e-mail list about emerging infections, on 15 September. Yesterday, the United Kingdom's Health Protection Agency (HPA) reported  that a 49-year-old Qatari man, who had traveled to Saudi Arabia and is now being treated in an intensive care unit in London, is infected with the same virus. Several other cases are reportedly under investigation; it's unclear whether the virus can be transmitted between humans or how big a threat it may pose to public health.
ScienceInsider talked to Ron Fouchier, a virologist at Erasmus MC in Rotterdam, the Netherlands, who sequenced the virus's genome and concluded that the Saudi and Qatari patients most likely are infected with the same virus. Questions and answers have been edited for brevity and clarity.
Q: What do you think we're dealing with?
R.F.: For the moment, all we know is that one patient has died and another one is terribly ill. Other cases are under investigation, but as far as I know they have not been confirmed. So for the moment, we're just assuming there were two individual infections, probably from some animal reservoir. They occurred 3 months apart, which is too long for one to have infected the other. I really can't speculate about it.
There are now six known human coronaviruses; one of them is SARS, but four cause the common cold and are quite innocuous. So let's keep both feet on the ground and not blow this out of proportion.
Q: How did your lab get involved in this case?
R.F.: We've been involved in the discovery of several viruses, including another coronavirus , and recently, we published a paper in PLoS ONE  describing a test for the entire family of paramyxoviruses. So when Dr. Zaki had cultured an unidentifiable virus from one of his patients, he e-mailed me, primarily because he wanted us to test it for paramyxoviruses, and then he sent us the virus. I asked him whether he had tested for coronaviruses, which he hadn't done yet. There's an assay developed by [the U.S. Centers for Disease Control and Prevention] that tests for all known coronaviruses. So while the virus was on its way to our lab, Dr. Zaki discovered that it was a coronavirus. But he does not have the facilities to sequence the virus, so that's what we did here.
At the time he posted the finding on ProMED, there was the patient in intensive care in London, so the HPA immediately started looking for a coronavirus as well, and that came back positive. They sent us the sequence of a very small PCR [polymerase chain reaction] fragment, just 200 nucleotides, and except for one nucleotide, it was identical to our virus. Of course, you need to sequence the entire genome, but based on this we can assume we're dealing with the same virus. In the meantime, we have sent the full genome and the virus itself to the U.K., so they can determine whether it really is.
Q: Why did you think it might be a coronavirus?
R.F.: We always think about coronaviruses. … Influenza, paramyxoviruses, and coronaviruses are the most obvious candidates when you have a serious respiratory infection.
Q: Do you want to study this new virus?
R.F.: Yes, we do. We've written a case report with Dr. Zaki about this first case and we're working on the annotation of the full genome, which we'll write up as a paper as well. But of course we'll need to start doing animal experiments. Initially, we assumed it was one isolated case in Saudi Arabia; now that the virus has surfaced in London as well, I think we'll need to become a bit more aggressive.
For starters, we'll find out whether animals get sick from this virus. You can isolate a virus from a patient, but that does not mean they died from it; to show that it causes disease you need to fulfill Koch's postulates. That's what we did for SARS , and it's what we hope to do here; we've applied for emergency ethical approval. The most obvious animal species to put this virus in are mice, ferrets, and perhaps monkeys. We've got to see what we can get approval for.