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Rhinovirus Rhinos=nose in Greek. What is the Rhinovirus?  Family of Picornoviridea  110 distinct rhinovirus types have been identified.  Responsible.

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Presentation on theme: "Rhinovirus Rhinos=nose in Greek. What is the Rhinovirus?  Family of Picornoviridea  110 distinct rhinovirus types have been identified.  Responsible."— Presentation transcript:

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.


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