Rhinovirus

Infection occurs rapidly, with the virus adhering to surface receptors within 15 minutes of entering the respiratory tract. Just over 50% of individuals will experience symptoms within 2 days of infection. Only about 5% of cases will have an incubation period of less than 20 hours, and, at the other extreme, it is expected that 5% of cases would have an incubation period of greater than four and a half days.^[24]

Human rhinoviruses preferentially grow at 33 °C (91.4 °F), notably colder than the average human body temperature of 37 °C (98.6 °F), hence the virus's tendency to infect the

The International Committee on Taxonomy of Viruses (ICTV) defines rhinoviruses as three species within the genus Enterovirus:^[27]

• Enterovirus alpharhino (Rhinovirus A)

• Enterovirus betarhino (Rhinovirus B)
• Enterovirus cerhino (Rhinovirus C)

Prior to 2020, enteroviruses (including all rhinoviruses) were categorized according to their serotype. In 2020 the ICTV ratified a proposal^[28] to classify all new types based on the genetic diversity of their VP1 gene. Human rhinovirus type names are of the form RV-Xn where X is the rhinovirus species (A, B, or C) and n is an index number. Species A and B have used the same index up to number 100, while species C has always used a separate index. Valid index numbers are as follows:^[2]

• Rhinovirus A: 1, 1B, 2, 7–13, 15, 16, 18–25, 28–34, 36, 38–41, 43–47, 49–51, 53–68, 71, 73–78, 80–82, 85, 88–90, 94–96, 100–108
• Rhinovirus B: 3–6, 14, 17, 26, 27, 35, 37, 42, 48, 52, 69, 70, 72, 79, 83, 84, 86, 91–93, 97, 99, 100-104
• Rhinovirus C: 1–57

Rhinoviruses have single-stranded

The viral proteins are translated as a single long

• Rupintrivir is a peptidomimetic drug developed for treatment of rhinovirus infections.^[32] Rupintrivir inhibits human rhinovirus 3Cprotease and prevents cleavage of the rhinovirus polyprotein following translation, therefore preventing viral assembly and replication. A phase II clinical trial of rupintrivir using experimentally induced rhinovirus infection in healthy volunteers demonstrated efficacy in reducing viral load and symptom severity. However, further trials testing rupintrivir in treating natural infections showed minimal benefit, and further clinical development was halted.^[33]
• picornaviruses.^[34] This drug acts by binding to a hydrophobic pocket in VP1, and stabilizes the protein capsid to such an extent that the virus cannot release its RNA genome into the target cell. Phase III clinical trials showed a slight reduction in symptom duration if taken within 24 hours of symptom onset.^[35][36] However, the FDA denied approval of pleconaril due to concerns about side effects, limited efficacy in non-white participants, and difficulty in treating most patients within a 24 hour window.^[37][38]

Other treatments aiming to reduce rhinovirus infection symptoms include immunomodulatory agents. These may promote beneficial antiviral responses or reduce inflammatory responses associated with symptoms. Interferon-alpha used intranasally was shown to be effective against human rhinovirus infections. However, volunteers treated with this drug experienced some side effects, such as nasal bleeding and began developing tolerance to the drug. Subsequently, research into the treatment was abandoned.^[39] Inhaled budesonide has been shown to reduce viral load and pro-inflammatory IL-1β in mice. Omalizumab, which was developed for treatment of severe allergic asthma, has shown evidence in reducing symptom severity of asthma patients infected with rhinovirus.^[33]

There are no vaccines against these viruses as there is little-to-no cross-protection between serotypes. At least 165 types of human rhinoviruses are known.^[2] However, a study of the VP4 protein has shown it to be highly conserved among many serotypes of human rhinovirus, opening up the potential for a future pan-serotype human rhinovirus vaccine.^[40] A similar result was obtained with the VP1 protein. Like VP4, VP1 also occasionally "pokes" out of the viral particle, making it available to neutralizing antibodies. Both peptides have been tested on rabbits, resulting in successful generation of cross-serotype antibodies.^[41]

Rhinovirus genome has a high rate of variability in human circulation, even occurring with genomic sequences that differ up to 30%.^[42] Recent studies have identified conserved regions of the rhinovirus genome; this, along with an adjuvanted polyvalent rhinovirus vaccine, shows potential for future development in vaccine treatment.^[43]

Human rhinovirus can remain infectious for up to three hours outside of a human host. Once the virus is contracted, a person is most contagious within the first three days. Preventative measures such as regular vigorous