Lecture 15. Introduction to Viruses

Question 1

What was the first written record of a virus?

Answer 1

Hieroglyph from Memphis drawn in 3700 BC showing typical clinical signs of paralytic poliomyelitis

Question 2

What did Ramses V die of in 1196 BC?

Answer 2

Smallpox

Question 3

What did Dmitri Iwanowski demonstrate (1892)?

Answer 3

Extracts from infected tobacco plants could transmit disease to other tobacco plant and that ceramic filters fine enough to remove bacteria did not prevent transmission

Question 4

What did Charles Chamberland develop?

Answer 4

Chamberland filter: porcelain filter to remove bacteria from drinking water
Pasteur found that rabies agent passed through it, thought it was a small bacterium

Question 5

What diid Martinus Beijernick demonstrate (1898)?

Answer 5

The agent multiplied only in cells (living dividing cells) and he called it a contagium vivum fluidum (soluble living germ) and used the term filtrable agent to describe this

Question 6

What did Loeffler & Frosch demonstrate (1898)?

Answer 6

Demonstrated Foot and Mouth Disease in cattle was caused by similarly small infectious agents, Foot and Mouth Disease Virus (FMDV) (picornavirus family)

Question 7

What did Carlos Finlay identify (1901)?

Answer 7

Indicated that mosquitoes were carrying the cause for yellow fever

Question 8

Who first mentioned and described phages?

Answer 8

Frederick Twort in 1915
He described how a phage infection of Staph gave rise to clear zones of lysis as phages appeared to destroy the bacteria

Question 9

Who was the first person to isolate phages and when?

Answer 9

Félix d’Herelle in 1917

Question 10

When was the first electron microscope developed?

Answer 10

1933

Question 11

When was the first EM of a bacteriophage?

Answer 11

1939

Question 12

What is a virus?

Answer 12

The smallest infectious agents (20-300nm)
A genetic element with a protein coat (capsid) and cannot replicate independently of a living (host) cell

Question 13

What are properties of viruses?

Answer 13

Contain DNA or RNA
Different replication strategy, do not divide by binary fission
Obligate intracellular parasites
Small, simple structure

Question 14

How does viral replication take place?

Answer 14

Assembly of pre-formed components into many new vial particles
Viral components produced (eclipse phase)
Component assembles to final viral particle

Question 15

What is CRISPR?

Answer 15

Gene editing tool