UK scientists believe they may have found a way to combat the common cold.
Rather than attacking the virus itself, which comes in hundreds of versions, the treatment targets the human host.
It blocks a key protein in the body's cells that cold viruses normally hijack to self-replicate and spread.
This should stop any cold virus in its tracks if given early enough, lab studies suggest. Safety trials in people could start within two years.
The Imperial College London researchers are working on making a form of the drug that can be inhaled, to reduce the chance of side-effects.
In the lab, it worked within minutes of being applied to human lung cells, targeting a human protein called NMT, Nature Chemistry journal reports.
All strains of cold virus need this human protein to make new copies of themselves.
Researcher Prof Ed Tate said: "The idea is that we could give it to someone when they first become infected and it would stop the virus being able to replicate and spread.
"Even if the cold has taken hold, it still might help lessen the symptoms.
"This could be really helpful for people with health conditions like asthma, who can get quite ill when they catch a cold."
He said targeting the host rather than the infection was "a bit radical" but made sense because the viral target was such a tricky one.
Cold viruses are not only plentiful and diverse, they also evolve rapidly, meaning they can quickly develop resistance to drugs.
The test drug completely blocked several strains of cold virus without appearing to harm the human cells in the lab. Further studies are needed to make sure it is not toxic in the body though.
Dr Peter Barlow of the British Society for Immunology said: "While this study was conducted entirely in vitro - using cells to model Rhinovirus infection in the laboratory - it shows great promise in terms of eventually developing a drug treatment to combat the effects of this virus in patients."
Fighting a cold
Colds spread very easily from person to person. And the viruses that cause the infections can live on hands and surfaces for 24 hours.
Painkillers and cold remedies might help ease the symptoms. But currently there is nothing that will halt the infection.
You can catch a cold by:
- inhaling tiny droplets of fluid that contain the cold virus - these are launched into the air when an infected person coughs or sneezes
- touching an object or surface contaminated by infected droplets and then touching your mouth, nose or eyes
- touching the skin of someone who has the infected droplets on their skin and then touching your mouth, nose or eyes
Symptoms - a runny or blocked nose, sneezing and sore throat - usually come on quickly and peak after a couple of days. Most people will feel better after a week or so. But a mild cough can persist for a few weeks.