Colds are among the most common infectious diseases. In poorer countries, they rank high on the list of causes of death. The culprits in this are the tiny rhinoviruses that have special properties.
What are rhinoviruses?
Rhinoviruses are RNA viruses that, unlike other viruses, do not have a lipid envelope. They have an icosahedron shape. Each of the 20 faces has a depression in its center to which the receptor protein binds. The outer capsid layer consists of a protein that does not allow antibody formation outside the virus. Rhinoviruses belong to the Picorna viruses and are specialized for colds and respiratory infections in humans and monkeys. They replicate particularly rapidly at temperatures between 3 and 33 degrees Celsius. Therefore, the cold pathogen finds ideal conditions for replication in wet and cold weather. About 110 subtypes of rhinoviruses have now been identified. They can be divided into three classes (rhinovirus A, B and C). The tiny virus, which causes colds, coughs, hoarseness, sore throats and respiratory infections, can be detected using the PCR test and forms viral proteins consisting of 2,200 amino acids. In a second step, these are broken down into the corresponding proteins with the help of two proteases (enzymes that break down proteins). People who have been in contact with different strains of viruses several times can push back their colds more quickly than people who have not.
Occurrence, distribution, and characteristics
Rhinoviruses are composed of a 20-sided capsid and are 24 to 30 nanometers in diameter. They are thermostable but sensitive to acids, alkyl-containing substances, and physical disinfection methods. Their single-stranded RNA has a length of 7,200 to 8,500 base pairs and a positive polarity. All three rhinovirus strains cause similar disease symptoms, although they share relatively little molecular similarity. Only humans and monkeys can become infected with the pathogens. They cause only minor tissue damage after entering the epithelia, but completely destroy the host cell when they exit. All types of chemokines respond to infection with the pathogen. These are signaling proteins that indicate to the immune system to produce increased numbers of granulocytes and T cells to fight the virus. People who were infected with rhinoviruses several times in childhood and responded with shortness of breath have a higher risk of developing asthma in adulthood. Rhinoviruses occur in at least 110 subtypes worldwide. Therefore, it is impossible to combat them using a single vaccine. The subtypes are categorized as rhinovirus classes A, B, and C based on their serological characteristics. Rhinovirus C, which was only discovered in 2009, is currently under scientific investigation. Rhinoviruses occur more frequently in the winter months and in late summer. For replication, 90% of types A and B use the ICAM I receptor. 10% of the subtypes enter host cells via the receptor for LDL cholesterol. Which entrance type C uses has not yet been clarified. Rhinoviruses preferentially replicate at temperatures below 33 degrees in the upper and lower respiratory tract organs (bronchi, lungs). After entering the host cell, the virus replicates its RNA in the endoplasmic reticulum with the help of RNA polymerase 3DPol. Upon leaving the cell, it destroys it. A new replication cycle is initiated every 12 hours. Rhinoviruses spread via droplet infection (sneezing, coughing on). A single sneeze hurls millions of them into the air at about 160 km/h. Affected persons also frequently become infected via smear infection (infected door handles, shaking hands, wiping eyes, etc.). The incubation period is between a few hours and 3 days. The pathogens can remain infectious for a long time, depending on environmental conditions. The person with a cold can excrete them until his or her illness heals (sometimes up to 3 weeks).
Diseases and symptoms
Rhinoviruses first enter the nose and infect the epithelial cells of the nasal mucosa. The sufferer develops a cold. They move on to the mouth and throat (sore throat, sore throat, hoarseness) and then to the bronchi and lungs, where they can cause cough, asthma and COPD attacks, bronchitis, and in children and people with immune deficiency, bronchopneumonia.In severe cases, infestation with rhinoviruses can even lead to life-threatening respiratory distress. Although these viruses are not the only pathogens causing the common cold, 2/3 of all colds are triggered by them. In individuals with an underlying condition such as bronchial asthma, they exacerbate the underlying condition. Because of the many subtypes, humans can develop resistance only to those of them with which their bodies have had previous contact. Babies and children are particularly at risk because their immune systems are not yet fully developed. Therapy is often symptomatic with cold remedies, nasal ointments, cough medicines and inhalation. The homeopathic remedy Pelargonium relieves bronchitis symptoms, sage helps with sore throat. Also, some home remedies provide relief and can help strengthen the body and immune system. Antibiotics are only useful if a superinfection is also present and a bacterial infection has developed in addition to the viral one. Preventive measures against rhinovirus infections include frequent hand washing and avoiding large gatherings of people during the cold season. Homeopathic echinacea strengthens the immune system. Vitamin C and zinc can be used preventively and also therapeutically against rhinoviruses.
