Lecture 22

Question 1

3 main scales of comparative genomes

Answer 1

• species / population level
• taxonomic scale (like family above species)
• community scale

Question 2

By comparing microbial genomes within a species/population, we can better understand:

Answer 2

• emergence events
• transmission events
• evolution of varients
• spread through time and space
• outbreaks trajectory
• changes in disease severity (virulence)

Question 3

Question 4

Question 5

Evolution of virulence - HIV

Answer 5

Question 6

Question 7

Why are some pathogens more fatal than others?

Answer 7

A large number of factors came into play
- immunity
- infecting dose
- host genetics and defence mechanisms
- medical treatment
- route of entry into the body

Question 8

Did pathogens evelove towards higher or lower virulence? - CLASSICAL veiw

Answer 8

Biologists traditionally believed that all pathogen populations would evolve toward low virulence

This is because damage to the host must ultimately be detrimental to the intrests of the pathogens that live within it (what this means is if its more virulent, it’ll cause you to stay at home and sick in bed you’ll have less chance of transmission. Where as less virulent causes you to have more chance of transmission

Question 9

Why are modern plague strains seemly less virulent than ancient ones?

Answer 9

Modern plagues are just as lethal, we are just better at treatment

Question 10

Two options a virus for a highly lethal virus

Answer 10

1. The highly lethal virus might evolve to become less lethal
2. The highly susceptible rabbits might evolve resistance

(Evolved to intermediate virulence, not lethal enough to kill before transmission occurs and rabbits evolved some resistance )

Question 11

Sometimes there is no selection pressure for having a lower virulence in cases where animals are not needed for transmission but instead transmission can happen via flies

Answer 11

Question 12

The classical veiw assumes that transmission is maximised only of the host lives but…

Answer 12

While a person is dying of malaria, they can still transmit the infection
- the host may even have less energy to swat away mosquitos —-> beneficial for transmission

Question 13

Ancheint diseases are just as virulent now as they were then

Question 14

Ebola virus had one single amino acid substitution which increased its virulence and transmissibility

Question 15

Answer 15

Can use a pylogenic tree to see how many mutations happened between each transmission AND THE ORDER OF TRANSMITTION and track them

LOOK AT NUMBER OF MUTATIONS BETWEEN TRASNMISSIONS TO INFORM TRANSMISSION DIRECTION

Question 16

What does the origin and spread of zika virus show

Answer 16

Comparing the genomes Reveals the duraation of pre-detection cryptic transmission: over a year before the first case was detracted

Question 17