An international team of researchers has found that one of the four coronaviruses responsible for the common cold – a virus known as HCoV-229E – originated in camels before being transmitted to humans.
The result comes as a surprise, because researchers didn't realise viruses could spread between the two species until 2012, when the Middle East respiratory syndrome (MERS) coronavirus made the jump from camels to people.
Now, the new study suggests that camels might be the cause of a whole lot of other infections – in addition to rhinoviruses and the three other coronaviruses, HCoV-229E is one of the main pathogens that causes the common cold you suffer from every winter.
"In our MERS investigations we examined about 1,000 camels for coronaviruses and were surprised to find pathogens that are related to 'HCoV-229E', the human common cold virus, in almost 6 percent of the cases," said lead researcher Christian Drosten, from the University Hospital of Bonn in Germany.
To figure out whether this was just a case of the virus being similar across all animals, the team performed a molecular comparison on the common cold virus in camels, humans, and bats, which are already known to be able to transmit disease to people.
Their result suggests that the cold virus wasn't just similar in humans and camels - it had actually jumped from camels to humans at some point in history.
They then took things a step further and isolated live camel-based common cold viruses, and witnessed the viruses entering the human cells through the same receptor used by HCoV-229E.
While a better understanding of where the common cold came from is important in itself, this research is even more crucial in trying to predict how MERS virus – which causes severe, often fatal, respiratory tract infections – spread from camels to humans, and how we can stop it in future.
The good news is that the team found that the human body is pretty good at defending itself against the camel common cold virus, which suggests a healthy immune system should also be able to fight off MERS.
The team also found evidence that camel HCoV-229E had changed significantly to be able to transmit from human to human. The same evolution doesn't seem to have happened in the MERS virus as yet.
"The MERS virus is a strange pathogen: smaller, regionally restricted outbreaks, for example in hospitals, keep occurring. Fortunately, the virus has not adapted well enough to humans, and has consequently been unable to spread globally up to now," said Drosten.
But the bad news is that, if the common cold virus eventually evolved to spread between humans, then MERS will most likely able to as well at some point, which means it's something researchers need to keep a close eye on.
"Our current study gives us a warning sign regarding the risk of a MERS pandemic – because MERS could perhaps do what HCoV-229E did," Drosten added.
A MERS vaccine is scheduled for clinical trials starting next year. Hopefully, as researchers gain a better understanding of MERS and systems at work behind it, they will find new ways of treating those infected and better ways to stop its spread.
The team's work was published in Proceedings of the National Academy of Sciences.