Medical Microbiology
Chapter 57
Picornaviruses - Rhinoviruses
Rhinoviruses
Pico-rna-viruses
Rhinoviruses cause the common cold
Structure:
Naked virus
Single-stranded RNA genome (linear)
Plus-strand of RNA (essentially an mRNA)
Contains 7200-8450 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?
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 (500-1000
viruses/ml)
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