Rhinovirus

Definitions & Key takeaways

Rhinovirus is a type of virus that causes the common cold. It infects the epithelium of the respiratory mucosa, typically through a nasal route of transmission. The result is an inflammatory response from immune cells, which leads to a runny nose, nasal congestion, sneezing, and sore throat. Diagnosis is usually made clinically, and the treatment focuses on symptom relief and preventing the spread of infection to others. To prevent the spread of rhinovirus, it is important to practice good hygiene, such as washing your hands frequently and avoiding close contact with people who are sick.

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Human Rhinovirus (HRV) is a communicable, infectious virus that causes inflammation of the nasal mucosa, or rhinitis. It mainly causes upper respiratory tract infections, and gets its rhino- name, meaning nose, because it commonly causes a runny nose, nasal congestion, and sneezing, as well as a sore throat and cough.
There are over 100 serologic known types and all of them can cause a "common cold” in humans! Now, rhinovirus belongs to the picornaviridae family of viruses.
They are naked viruses, about 30 nanometers in diameter, and they’re surrounded by an icosahedral capsid, which is a spherical protein shell made up of 20 equilateral triangular faces.
And they’re “naked” because the capsid isn’t covered by a lipid membrane. They’re also single-stranded, positive-sense ribonucleic acid, or RNA, viruses.
This means that their RNA is actually mRNA, which the host cell ribosomes use to make viral proteins. Unlike other picornaviruses, rhinoviruses are acid labile.
That means they can be destroyed by stomach acid, so they don’t typically infect the GI tract and don’t spread through a fecal-to-oral route.
On the other hand, rhinoviruses commonly infect the epithelium of the respiratory mucosa, which lines the nasal cavity. So rhinovirus transmission occurs through contact with infected respiratory secretions, like snot and aerosols, particularly from nose blowing or sneezing.
Touching an infected surface, like a door handle or shaking hands, and then touching an uninfected respiratory mucosa is a main way to transfer an infection - that’s because rhinoviruses can survive up to 2 hours on the skin, and 4 days on surfaces.
Once rhinovirus has been introduced to the respiratory mucosa, it targets cell surface receptors expressed at the surface of nasal epithelial cells.
Rhinoviruses can target a few specific receptors for entry, but one in particular is intercellular adhesion molecule-1, or ICAM-1.
This attachment allows for rhinovirus to be eaten, or endocytosed, into the host cell. During the endocytosis process, the icosahedral capsid breaks open, allowing the single stranded RNA of Rhinovirus to gain access to the host cell cytoplasm.
In the cytoplasm, the host cell ribosomes take over viral protein production, helping the virus replicate. Now, when the host cell realizes it’s been infected, it releases proinflammatory proteins, like cytokines and chemokines, to activate and attract immune cells to the site of infection, and recruit even more immune cells from blood vessels in the lamina propria, the layer just under the epithelium in the respiratory mucosa.
And the end result is local inflammation. Rhinovirus infections can occur in any individual, but there are some groups who are more susceptible, like young children, the elderly, and individuals who are immunocompromised, or have underlying respiratory diseases like chronic obstructive pulmonary disease, asthma, or cystic fibrosis.
The symptoms of a rhinovirus infection are actually those often associated with the “common cold”. Symptoms usually begin about 1 to 2 days after infection, and can last for about 2 weeks.
And typically, they include nasal congestion and irritation, which can mean a runny nose; sneezing; pressure in the head that results in headaches, or sinus, ear or facial pressure; or a loss of smell and taste.
But can also include fatigue, malaise, or loss of appetite; and other symptoms of an upper respiratory infection like a sore or irritated throat; a cough; or hoarseness.
And while symptoms are usually mild, factors like age, immunocompromised states, and underlying respiratory diseases can result in much more drastic, and sometimes even more complicated, life-threatening symptoms.
Rhinovirus is mainly diagnosed clinically; especially when “common cold” symptoms are present without additional complications, concerning physical findings, or relevant medical history.
A definitive diagnosis can be made with PCR testing of cultures from nasal secretions or washings, but this is typically only done in more complex cases, like if an individual is immunocompromised or has an underlying respiratory disease.
Now, because rhinovirus infections tend to be mild and self-limited, treatment typically centers on relieving symptoms and preventing other people from becoming infected.
So, common symptom relievers include rest, hydration, and age-appropriate over the counter medications, like first generation antihistamines, NSAIDS, and nasal decongestants.
And general precautions should be taken to limit spreading the virus, including covering coughs and sneezes, thorough hand-washing especially after nose blowing, and regular disinfecting of surfaces.
Ok, so to recap: Rhinovirus is a type of picornavirus which is the leading cause of the common cold. It infects the epithelium of the respiratory mucosa, typically through a nasal route of transmission.
A consequence of the inflammatory response from immune cells leads to rhinitis and the hallmark symptoms of the common cold, including runny nose, nasal congestion, and sneezing.
A clinical diagnosis is usually made and treatment tends to center on symptom relief and preventing the spread of infection to others.