More than 170 rhinoviruses are known to science, and these viruses—the common cause of colds—are present in noses worldwide. While rhinovirus infections often cause mild symptoms, they can be deadly for some.
Recent research reveals that rhinovirus infections are linked to a significant number of asthma attacks and are a primary trigger for COPD flare-ups, which can cause dangerous breathlessness and coughing if left untreated.
The severity of symptoms isn’t necessarily tied to the virus itself. “It’s pretty clear now that if you give someone with asthma or COPD a [rhino]virus and then you give the same dose of rhinovirus to a healthy person, the response is quite different,” explains Aran Singanayagam, a clinician scientist at Imperial College London.
Scientists studying this phenomenon have been infecting nasal tissue grown in a lab with rhinovirus. A modern study, published in the journal Cell Press Blue, found that when the tissue’s initial defenses fail, a mild infection can quickly escalate. This confirms that differences in the host’s immune system—rather than the virus’s behavior—are the primary driver of these effects.
A Detrimental Delay
When nasal tissue is infected with rhinovirus in a lab setting, only a small percentage of cells—about 1%—become infected, mirroring what is often seen in mild or asymptomatic colds, according to Ellen Foxman, a professor of immunobiology at Yale School of Medicine.
However, all cells in the tissue exhibit altered behavior. When infected cells release molecules called interferons, they act as warning signals, prompting neighboring cells to activate their antiviral defenses and preventing the virus from spreading.
Researchers then investigated what happened when the interferon signal was blocked. They observed that the tissue began to produce excess mucus and inflammatory signals. “That’s what you see in people with a cold, or people with asthma or COPD attacks–you see excessive mucus production, and you see those inflammatory cells coming to the lung,” Foxman says.
“The timing really matters,” Foxman continued. “If that response is delayed enough to let the virus replicate and get big enough to trigger other pathways, that’s when you’re going to see the symptoms.”
This delay aligns with findings from other studies, notes Nathan Bartlett, a professor at University of Newcastle in Australia. “We found that if you took cells from an airway that has been chronically exposed to inflammation, there’s been a desensitization,” he says. “It just takes them a bit longer to realize that there’s an infection. And so there’s a delay, we saw, by about 24 hours.”
For a rhinovirus, a 24-hour delay allows the virus to multiply substantially before the immune system can effectively respond.
A Way Forward
While the study focused on a limited sample of nasal cells, it identifies key signals released by cells when the initial immune defenses are compromised. Researchers hope this information will lead to the development of drugs to prevent dangerous reactions to rhinovirus.
Intervening in the inflammatory process is challenging due to its rapid progression. Researchers speculate that a universal treatment or vaccine could be the most effective approach to protect vulnerable populations.
“I’ve seen a number of papers recently that are talking about universal vaccines,” Bartlett says, “which might stimulate the immune system to provide protection against viruses of all kinds. If such a vaccine is ever brought to the clinic, scientists will be watching to see how it plays out with rhinoviruses.”
“You can bring rhinovirus into the conversation now,” he concludes, “because that’s probably the virus we’re going to be encountering, actually, more than anything. So we better start thinking about it.”
Frequently Asked Questions
What is a rhinovirus?
Rhinoviruses are the most frequent viral cause of upper respiratory infections worldwide, and are known to cause the common cold, but also play major roles in severe respiratory disease and asthma exacerbations.
How do rhinoviruses affect people with asthma or COPD?
Rhinovirus infections are behind a staggering number of asthma attacks and are a leading cause of flare-ups in people with chronic obstructive pulmonary disease (COPD), causing breathlessness and coughing.
What did the recent study in Cell Press Blue reveal?
The study found that when the tissue’s first-line defenses fail, a mild infection can spiral out of control, confirming that differences in the host’s immune system—not the virus’s behavior—are behind these effects.
Given the prevalence of rhinoviruses, what role should research into preventative measures, like a universal vaccine, play in public health?
