1. Rhinovirus Rhinos=nose in Greek

2. What is the Rhinovirus?  Family of Picornoviridea  110 distinct rhinovirus types have been identified.  Responsible for ~50% of common colds in humans.  Lysic in nature (killing cells)  Spread through water droplets in respiratory system.  single-stranded positive sense RNA genomes of between 7.2 and 8.5 kb in length.RNAkb  Viral capsid is icosahedral (20 faces) in shape.  Rhinovirus types are most active in early fall, spring, and summer.  They can live up to 3 hours on non-porous surfaces

3. Viral Reproduction To infect cells:  Virus attaches to cellular receptors and destabilizes the virus particle shell.  Viral genome is released directly into cell.  The (+) RNA strand is immediately translated at a ribosome and made into a polyprotein.  vmRNA has a special initiation start sequence so it doesn’t need a 5’cap.  The polyprotein is cut into smaller pieces to produce the viral proteins that it uses to make more copies of itself.

4. What do the parts of the polyprotein make? 1.In a vesicle: vRNA polymerase: makes more copies of vRNA, and (-)strand RNA to make more (+) RNA for export. 2.Protein is made for the protein shell (capsid) of the newly forming viruses. 3.Produces a protein that stops normal, cellular mRNA 5’cap from being produced= no cell proteins can be made, only virus.

5. How does the Virus leave the cell? Once the capsid is made, a new (+) RNA molecule is tucked inside of it, it bursts from the cell killing the cell. NO MEMBRANE IS TAKEN.  From infection to bursting out of a cell, only about 8 hours are required.  This is a fast acute infection.

6. Virus Spread  Spread mainly by coughs and sneezing.  Capsid will break apart at high temps, so the virus likes it a bit cooler than Influenza – 91F  91F is about the temp of the nose, therefore it tends to infect the nose cells.

7. Evading Host Defenses  Rhinoviruses interrupt the cell system used to transport interferon out of rhinovirus infected cells. No interferon=no warning to die  Most of the fighting is done by the innate system: interferon, phagocytes, and NK cells  The adaptive immune system doesn’t really have to work at all. Unfortunately, no antibodies get made against the Rhinovirus, so it can re-infect the same person over and over again.  Rhinovirus RNA is subject to antigenic shift, so the virus might be able to stump the adaptive immune system.

8. Pathology Most symptoms are due to the quick death of cells from the innate system’s fight. Symptoms usually begin 2 to 3 days after infection. The symptoms of infection with this type of virus often include: Mucus buildup in your nose Difficulty breathing through your nose Swelling of your sinuses : due to inflammation Sneezing : due to inflammation Sore throat Cough Headache Fever is low

9. Pathology continued…..  The capillaries of the nose “leak” and you have a runny nose, or they swell and you are stuffed up. (too many cytokines running around).  Sneezing can cause the virus to be shoved up the Eustachian tubes and into the sinuses causing a middle ear infection (pain) or sinusitis. (green snot)  Macrophages eating the Rhinovirus release IL-1, a cytokine that triggers the fever. Increase body temp, reduce the viral capsid’s ability to stay together.