[Music] These various infections are very, very common. In fact, approximately 50% of all common colds are caused by rhino varuses. [Music] Virological with Florian Kramer. [Music] Hello and welcome to this week's episode of Virological. This episode was recorded on January 18th of 2026 in Vienna. In this episode, we're going to talk about a virus infection that all of us already had, probably multiple times. It's an upper respiratory tract infection that's caused by rhino viruses. Just about the name, rhino basically comes from ancient Greek and means from the nose or off the nose. So basically, we're dealing with a virus here that infects the nose, infects the upper respiratory tract. Actually, we're dealing with a whole bunch of different viruses, as you will see. Rhino viruses are part of the big horn of viruses, so it's related to Bollio and it belongs to the genus of entero viruses. These viruses are positive strand RNA viruses. They don't have a lipid envelope. They're about 24 to 13 nanometer in diameter. So pretty small. They have four structural proteins that form the shell or the envelope. They're called BP1. So, viral protein 1, viral protein 2, viral protein 3, viral protein 4. They form symmetric structure. They actually extract these 60 copies of each of these proteins in the virus particle. As I mentioned, it's a whole group of viruses. They're pretty diverse. We have three different types. We have human rhino virus A, human rhino virus B, and human rhino virus C. And within these groups, there's a lot of diversity in terms of zero types. In the human rhino viruses A, we have about 80 different viruses. For B, we have about 30 different viruses. And for C, we have about 50 different viruses. So really, humongous diversity. And these viruses also use different surface proteins on our cells to attach to the cells and get into the cells. Human rhino viruses A and B mostly use proteins that are called ICAM1. That's an integrain on the surface of our cells. So, about 90% of A and B rhino viruses use that. And about 10% of A and B rhino viruses use LDL receptor. So that's basically the LDL cholesterol receptor. Rhino virus C uses CDHR3. That's a catering. So that's a different protein, a different receptor. A little bit about history here. The virus was first isolated. Or Rhino viruses were first isolated in 1956. By Winston Price at Johns Hopkins University in Baltimore, he isolated the virus from a group of nurses that had mild upper respiratory tract infection. And he called the virus CH virus. So for Johns Hopkins, basically. In 1985, the structure of the virus was solved using X-ray crystallography. And that was done by a team from Purdue University and University of Wisconsin, led by McLeod Rossman. Until 2006, we only had human rhino virus A and human rhino virus B. And in 2006, human rhino virus C was discovered in New York and in Australia. So a little bit about the illness and the symptoms that the virus infection can cause. First of all, how can you get infected? There's multiple ways. The virus can get transmitted via aerosols. These are these really tiny little droplets that stay in the air for a long time. It can also be transmitted by larger respiratory droplets, but also by formats, meaning via objects to contaminated cell phones, for example, or a direct contact with an infected person. The reproductive number, or R-not, so the number that tells you how many people and infected person will infect is about 2.5. So that means that rhino viruses are a little bit more infectious than influenza viruses, for example, which have a nR-not of about 1.5. But they are less infectious than currently circulating variants of SARS-Coronavirus 2. The incubation time is approximately two days, but it can be as short as 20 hours and as long as four days. And when you get symptoms, the typical symptoms are runny nose, stuffed nose. So typical common cold symptoms may be a sore throat, a little bit of coughing. So it's mostly the upper airways that are involved. Sometimes you also can have fatigue, you can have a headache, maybe muscle pain, maybe diarrhea, but that's relatively rare. And in very rare cases, people can get fever. But again, if you have a respiratory tract infection, you have fever. It's unlikely to be a rhino virus. These virus infections are very, very common. In fact, approximately 50% of all common colds are caused by rhino viruses. Typically, in the North and Hamnes fear, we have more circulation during the cold season from September to April. But it's not like rhino virus infections stop during the summer. You can get infected during the summer as well. It's just not as common as during the winter season. It's also important to mention that a lot of rhino virus infections are asymptomatic. The assumption is that in kits, about 15 to 30% of the infections are asymptomatic, and 50% of the infections are asymptomatic in adults. Once you had an infection with a specific rhino virus, you actually make neutralizing antibodies that can protect you from reinfection. But the problem is, they're very specific to that strain that infected you. In fact, there's more than 150 different strains. So unfortunately, immunity doesn't protect you from the other strains. And so, if you get exposed to another strain, you will get infected again. I already mentioned that these viruses usually cause upper respiratory tract infections that are relatively mild. One reason for that is that these viruses grow at low temperature. They prefer 30 to 35 degrees Celsius. They don't grow well at 37 degrees Celsius. And that basically means that they're kind of restricted, in most cases, to the upper airways, where it's colder. If you go down deep into the lung, the temperature gets higher and higher. And they basically restrict their growth. And that might be one of the reasons why most of these infections are mild. But they can also be more severe infections, specifically with rhino virus A and human rhino virus C. And typically, human rhino virus B infections are very mild. And the more severe forms of the rhino virus infections occur, typically in small children or babies, in very old people and in people with a compromised immune system. And in some cases, this can lead to bronchialitis or even to pneumonia. Just to explain a little bit what bronchialitis means and where bronchial ulcer are. So typically in our airways, we have bronchus, which kind of is the bigger airways. And then at the very end of the airways, they're the alveoli. It's like little bubbles where the gas exchange between blood and the air happens. And this small airways that connect the alveoli and the bronchus are called bronchialis. And they're very, very thin. And if you get infections there and this can happen with human rhino virus, then you have issues breathing and that can be more severe. What also should be mentioned is that rhino viruses often co-infect people with other viruses, but also with bacteria. And that can also contribute to more severe infections. And I think it should also be mentioned that before the pandemic, often nobody tested for rhino viruses. And now there's a lot more testing with these test panels where you can actually test a number of respiratory viruses at the same time. And now it turns out that sometimes in more severe infections, rhino viruses involve two and that hasn't been reported that much before the pandemic, just because there was less testing. I think I also should mention that there's an association between rhino virus infections and asthma. And there can be two associations. The first one is that it seems that rhino virus infections can actually set up people to get asthma later on in life. That often happens when babies, for example, very small children, I have more severe infections with just right now where is this version?
the virus reaches these bronchules and then these kits have a higher risk of getting asthma later in life. And it seems that in terms of virus infections, rhinovirus infections are the second most cause of asthma after RSV. So RSV is another respiratory virus that's known for setting people up to get asthma later in life. And then there's another association which is that if somebody already has asthma and gets a rhinovirus infection, the infection can exacerbate the asthma quite a bit so that can be highly problematic too. So what can you do about rhinovirus infections? The truth is not much. There are no vaccines. There's some vaccine development but it's not very far and it's really hard to make vaccines against rhinovirus because they're so diverse, they bind to different receptors and because most of the immunity that you get is really strange specific. So it's really hard to make vaccines that would work against all these diversity, all these different rhinovirus maybe even harder than making a universal flu vaccine. And that's why vaccine development is not that far. And so far we also don't have any kind of antivarials that really work well against rhino viruses. So basically if you get an infection, there's not much you can do about it other than write it out and there's actually not much you can do in terms of preventing an infection except for distancing and maybe masking and washing your hands and so on and so forth. Of course because these virus infections are relatively mild and relatively harmless. In most cases these viruses also haven't been prioritized for vaccine development and for antiviral development. So to summarize all of these rhinovirus are very diverse group of viruses that cause many many infections, very common infections that are often mild and even though they are annoying they are not very dangerous. But in some cases they can also lead to bigger problems and even fatalities have been recorded with rhinovirus but again tons of infections most of them harmless and mild. That's it for today for Virological. I just wanted to mention if you have any comments or suggestions or questions please feel free to write an email to
[email protected] and at some point we will have an episode where we answer questions and comments that came in. Thanks for listening and until next week, bye. If you're enjoying the podcast and would like to support our work visit us on Steady. You'll find the link in the show notes and don't forget to follow and leave a review on your favorite podcast app. Podcast Workstaff.
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