Rhinoviruses: The common cold Flashcards
1) know relationship between genome structure, its replication strategy, and cytopathic effects on the host cell 2) Differentiate viruses that cause common-cold symptoms based on replication strategies 3) Know symptoms 4) Know why there isn't a rhinovirus vaccine
Classify rhinoviruses
Picornaviridae family:
1) Non-enveloped
2) + strand RNA
3) acid labile (i.e. cannot survive in low pH)
What is the significance of being non-enveloped?
1) It can persist for long periods of time on surfaces
2) Relatively resistant to desiccation
What 3 receptors are used to serotype rhinoviruses?
1) ICAM-1
2) LDL
3) Sialoprotein receptors
What does it mean for rhinoviruse to be +RNA stranded?
Upon entering the cell, the RNA can immediately be translated into viral polyproteins
What do rhinovirus viral proteases bind to and inactivate within the cell?
“cap-binding complex” that is required for translation initiation of host mRNA’s
How are viral proteins selectively translated?
5’ end of the RNA has a region called IRES, allowing it to bind inactivated host ribosomes and still be translated .
What contributes to the disease symptoms of the virus?
Inflammatory responses, NOT direct viral damage
Summarize the VF’s of rhinoviruses:
1) Viral protease + 5’ IRES allows selective viral translation
2) Over 100 serotypes = no complete immunity to it
3) Non-enveloped capsid = can last on materials in environment for a long time
How long does the virus incubate before symptoms present?
12-72 hours
If systemic symptoms such as fever and malaise present, what should you think?
Alternative diagnosis other than rhinovirus
Do you see pharyngitis with rhinovirus?
No. You should not see erythematous or exudative lesions with rhinovirus.
When do rhinovirus infections appear most often?
Fall and spring.
How is rhinovirus transmitted?
Which receptor is involved?
1) aerosolized droplets (coughing)
2) Fomites (contaminated surfaces)
3) Hand-to-hand contact
**ICAM-1 is involved in the virus getting into the cell
If you see conjunctivitis and nasal polyps in a person with cold symptoms, what should you think?
Adenovirus infection
Why can’t a vaccine be made for rhinovirus?
Too many serotypes
