1. Chapter 57 Picornaviruses - Rhinoviruses
Medical Microbiology
Chapter 57
Picornaviruses - Rhinoviruses

2. Rhinoviruses Pico-rna-viruses Structure:
Rhinoviruses cause the common cold
Structure:
Naked virus
Single-stranded RNA genome (linear)
Plus-strand of RNA (essentially an mRNA)
Contains bases with a poly-A tail
The genome alone is able to cause infection
Human Rhinoviruses consist of at least 100 different serotypes
Importance in cold recurrence
Vaccine?

3. Rhinoviruses Infection may be initiated by as few as 1 virus
Attachment occurs through the ICAM-1 molecule on epithelial cells
Viral replication shuts down normal cellular RNA and protein synthesis
This is the primary cause of pathology
Infected cells release inflammatory chemicals which stimulate nasal secretions (“runny nose”)
Viruses are shed in nasal secretions ( viruses/ml)

4. Rhinoviruses The viruses replicate poorly at above 33º C
Confined to upper respiratory tract
Implications for cold weather infections?
Transmission – virus can be passed by aerosols or contact with fomites (naked virus)
Hands seem to be the major mechanisms of transmission
Box 57-5 and 57-6
Info. from other text