Cold truths from the world of virology

At the Research Matters Curiosity Shop people ask questions they’d like Ontario university researchers to answer. Recently, a visitor to the Shop asked: “Can we ever cure the common cold?” Research Matters tracked down Ana Sanchez, an infectious disease expert and instructor of medical microbiology at Brock University to get some answers.

Spoiler alert: It does not sound as though the facial tissue and cough medicine industries are in any danger.

Research Matters:    Why is it so hard to find a cure for the common cold?  
Ana Sanchez:    The first reason is because the disease is not caused by a single pathogen. There are more than 100 types of rhinoviruses that cause the symptoms we have come to know as the common cold. Then we have adenoviruses, coronaviruses and other groups that cause colds as well. Within each group, many variations can occur, providing different qualities to viruses, to which we must adapt and so our immune system can react appropriately . It would be a challenge to find a drug or vaccine that targets of them.

So, the diversity of the pathogens is, is the first challenge.

RM:     What else?
AS: Another challenge is that these viruses change a lot. They mutate. So even if we were to create a treatment it would be like a moving target.  It would be like the influenza, where we have to make new vaccines the time. Unless scientist find a special part of the virus molecule; a molecule that is common to an entire group and does not change much, the challenge will remain.

RM: Are viruses more challenging to treat than bacterial infections?
AS: For the longest time we were not able to create drugs to treat viral infections because scientists couldn’t identify a particular physiological aspect of a virus they could target. Bacteria are cells – living organisms with active metabolisms. They have membranes, cytoplasms, and nuclei we could decipher. We understand them better, which makes them easier to fight.

With viruses, we now know we’re not targeting live cells. Viruses are actually not “alive” although they carry a code for life. They don’t replicate by themselves, they don’t have metabolism.  They are the ultimate parasites and need to colonize a cell to do that, right?  So even when we may have drugs to inactivate viruses, because they live inside our cells, many time we end up damaging our own cells as well. As biotechnology advances, however, scientist are more able to conceive drugs or treatments to fight viruses off without causing too much damage to the patient.

Now, not viral infections are difficult to deal with. Some viruses, like hepatitis B are very stable, so it was possible to create a vaccine you can trust. It depends on the virus.

RM: Can scientists learn anything from the human immune system about curing colds?
AS: They could, but that’s really beside the fact. We get an infection, and our body successfully deals with it within a few days. We mount a strong cellular and antibody response and end up winning the battle.

But then we get another virus and another. There’s no end to the diversity of cold viruses.

RM: So, what’s the long-term prognosis for a cure?
AS: Curing the common cold is a terrible challenge. And remember that it is not really a severe disease. For most people, it is a nuisance. There’s a lot of people with the illness, but it’s not like influenza or other respiratory diseases that tend to be more serious. And even if there was a vaccine that worked for some cold viruses, it’s going to be hard to convince people that the vaccine works because they will get another cold from another virus and think, ‘Well this vaccine didn’t work well.’

RM: Is this just a never-ending battle, then?
AS: Each time there is a medical advance in virology – like the way we’re starting to better control HIV – we think we’re winning the battle against infectious agents. We have better drugs and people are living longer.  Then, boom, there’s something else.

Take Ebola. In the mid-1970s, Ebola became an issue for a period of time, and then we heard nothing for years. We thought maybe it was just a fluke. And then just comes back.

Of course, living a healthy life with good nutrition and good rest will improve your immune system to fight pathogens. And fighting pathogens (most of the time successfully) is something that we humans have been doing forever…

We are born with an immune system exactly because we need to fight these pathogens.  It’s there for a reason. But the other side is also always going to be there.

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