Intro to Virology

Question 1

Viruses are…

Answer 1

Classic definition: OBLIGATE INTRACELLULAR PARASITE

“A bit of bad news wrapped up in a protein”

Viruses contain RNA or DNA

Question 2

Viral Groups

Answer 2

Question 3

Viral Key

Answer 3

Question 4

Complex Capsids

Answer 4

Bacterial shapes are often used as a method of Classification - Viruses CANNOT be classified this way!!!

Question 5

Helical capsids

Answer 5

Question 6

Icosahedral Capsids

Answer 6

Question 7

Assembly pathway of bacteriophage T4 - a bit of both

Answer 7

Question 8

The Virus Replication Cycle

Answer 8

Question 9

Attachment - tropism

Answer 9

RECEPTORS! Define!tropism,! If!a!cell!lacks!the! Receptor,!it!can’t! be!infected.! EXAMPLE:! 2A6!sialic!acid!is!the! receptor!for!human!flu,! 2A3!sialic!acid!is!the! receptor!for!bird!flu.! Pigs!have!BOTH! molecules!in!their!lungs!

Question 10

Sense and Antisense

Answer 10

Question 11

Consequence of Segmented Virus Genomes - “viral sex”

Answer 11

• Segmented genomes make possible the reassortment of genetic information. • Reassortment is a powerful means of achieving rapid generation of genetic diversity; this could be another possible reason for its evolution. • Segmentation of the genome also has implications for the partition of genetic information and the way in which it is expressed.

Question 12

Double-stranded virus RNA replication

Answer 12

Question 13

Routes of Viral Entry

Answer 13

Question 14

RNA viruses – take home messages

Answer 14

Important features that are useful to understand:

– Physical organisation of RNA genome (simple versus complex)

– Genetic organisation of RNA transcription (simple versus complex)

– Common viral replication strategies (devious tricks)

– Unique advantages of being RNA based

– Unique Problems of an RNA genome

– Effects of segmented and non-segmented genomes and their role in viral evolution

– Cause acute resolving infection (paramyxoviruses, rotaviruses)

– Cause chronic infection (HCV, HIV)