Evolution & medicine

Question 1

What is the difference between HIV and AIDS

Answer 1

HIV is the lentivirus that causes the disease AIDS

Question 2

What does HIV do

Answer 2

Attacks CD4 ‘helper’ cells of the immune system

Question 3

How can we sequence virus genome

Answer 3

Virus genome often inserted into human genome (in infected cells). Can then isolate viral genomes from infected patients

Question 4

What process do we use to isolate viral genomes

Answer 4

PCR - Polymerase Chain Reaction

Question 5

How do we use phylogenetic trees

Answer 5

Compare relatedness of different viral sequences from multiple patients

Question 6

When are virus genome sequences most closely related

Answer 6

Within the same patient rather than between patients

Question 7

What are the two ways we can explain shared and differing characteristics of virus genomes

Answer 7

1 - Infections from multiple viruses

2 - The viruses are changing

Question 8

Evidence for and against infections from multiple viruses

Answer 8

For - Multiple sequences, Infection from ‘bulk source’ (blood transfusion)
Against - Pattern of tree (viruses within patients more similar than between)

Question 9

Evidence for and against changing virus

Answer 9

For - Within patients more similar than between, suggests single point entry and then diversification
Against - Occasional patient may vary.

Question 10

What is the difference between proximal and ultimate questions

Answer 10

Proximal - By what mechanism is change occurring?

Ultimate - What is causing the change?

Question 11

What do we know about HIV

Answer 11

Lentivirus (kind of retrovirus),
RNA genome
Infects and damages immune system cells

Question 12

How is diversity generated in HIV

Proximal

Answer 12

Reverse transcription less accurate than DNA transcription. This means more mistakes occur and are replicated. Causing mistakes and variation in genome

Question 13

Why is diversity generated

Unlitmate

Answer 13

Natural selection - Changes selection pressures on bacteria and causes evolution

Question 14

What are some possible selection pressures on viruses

Answer 14

Immune system, Drugs, receptor changes, tropism in tissue

Question 15

What are the consequences of HIV evolving

Answer 15

HIV fastest evolving thing that we know of.

Develops resistance to therapy quickly and rapidly - making efficient vaccines incredibly hard

Question 16

Why does HIV evolve so quickly

Answer 16

It has a lifecycle of 20 minutes.

Question 17

What is the estimated size of an HIV ‘armada’

Answer 17

Est. 5x10^10 different variants within one patient

Question 18

Is HIV the only microbe that evolves

Answer 18

Many pathogens evolve within host in same way.
Antibiotic resistance spreading through pop. evolutionary
Our own genome evolves in response to pathogens

Question 19

How can we use knowledge of evolution in medicine

Answer 19

Can help us understand and better respond to pathogens. (How they respond to hosts and therapies)