RNA Viruses- Picornaviridae and Orthomyxoviridae

Ahhhhhh CHOOOOOOOoooooo!!!


https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQuON4WQwZ5i6p5ocUlbZ6Vkmk-C6DKjhAQ25OAB0iYJ4AH45MN7G1lyj3B-iwUUBSfK3syID6KgRU6F5f5YDDIeSr0lpsYYDNf2I5L0ZJQEG5LDmVEzAkRtccdu-U9-Yu5WkV-mFTZZE/s320/sneeze1.jpg

Unique features of RNA Virus

1. Genome is infectious (+ RNA virus)
2. Unusual structural characteristics
   

Picornaviridae

Genome

1. One linear (+) RNA
2. Long untranslated region end of 5’end “clover leaf” structure
3. Single polyprotein
4. Both ends modified

Morphology

• Virions (naked)
• Nucleocapsid isometric
• Incomplete or empty capsids common

Picornaviridae- Rhinovirus

Orthmyxoviridae-Influenza

Genome of Influenza A&B

1. ss(-) RNA in 8 segments
2. 3 polymerase polypeptides with each segment
3. 5’ and 3’end of all segment highly conserved
   

Morphology

• Typically spherical
• Enveloped
• Pleomorphic (many forms)
• Spikes on envelope
• Groups of HA

What is the difference between Cold and Flu?
http://www.simcoemuskokahealth.org/images/Flu-cold-chart.gif

Antigenic Drift vs. Antigenic Shift

Antigenic drift is a mutation in the genetic code of surface antigens ( HA/NA)

Antigenic shift occurs when genes re-assort form different subtypes

Strain Naming Convention

Write according to this order:

1. Type

2. animal species (omitted if human)

3. place of isolation

4. number of isolate

5. year of first isolation

6. (H and N subtypes)