The “rhino” in rhinovirus is derived from the Greek for “nose” and these viruses are the most common infective virus to cause the common cold in humans. Rhinovirus describes species that belongs to the enterovirus genus of the family Picornaviridae. Other enteroviruses belonging to Picornaviridae include poliovirus and Coxsackie A virus.
Rhinovirus is one of the smallest types of virus, with a diameter of around 30 nanometers. Most other viruses such as vaccinia or smallpox are around ten times this size, with diameters of about 300 nanometers.
Rhinoviruses contain single-stranded positive sense RNA as their genetic material. These RNA genomes span a length of between 7.2 and 8.5 kb. At the 5' end, there is a virus-encoded protein and at the 3’ end there is a 3' poly-A tail, as in mammalian mRNA. Structural proteins are coded for in the 5' region of the genome, while non-structural proteins are coded for in the 3' portion. This applies to every picornavirus. There is no envelop enclosing the viral particles and the structure of the virus is icosahedral. Optimal growth of the virus is achieved at somewhere between 33 and 35 °C, which is the temperature range found in the human nose.
Around 100 rhinoviruses have been identified, all of which differ according to the proteins presented on their surface. As the predominant cause of the common cold in humans, primary symptoms of this condition include runny nose, sore throat, cough, sneezing and congestion. These symptoms may be accompanied by headache, muscle ache, muscle weakness, malaise and loss of appetite.
Children can suffer from as many as twelve colds a year and in the United states, with colds occurring more commonly between September and April. This may be attributed to the school year starting around September and to people spending more time inside and within closer proximity of each other during these months. Lower temperatures may be another factor, particularly outdoors, given that rhinovirus would favor 32˚C for replication over 37˚C.
Reviewed by Sally Robertson, BSc