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CELS191 > Evolution & Medicine > Flashcards

Evolution & Medicine Flashcards

1
Q

What is HIV?

A

A lentivirus that causes AIDS

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2
Q

Where does infection of HIV occur?

A

Through bodily fluids

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3
Q

How many deaths occurred between 1981 and 2006?

A

WHO estimates 25 million

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4
Q

What happened before the disease was recognised?

A

It was occasionally spread through contaminated blood products

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5
Q

How much of the population does HIV affect?

A

0.6%

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6
Q

How many deaths are as a result of HIV?

A

3.5% of deaths worldwide (5.7% in low income countries)

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7
Q

What does the HIV virus infecting cause?

A

Failure of the immune system

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8
Q

HIV is a virus and…

A

has a genome

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9
Q

What happens with the HIV genome?

A

It is often inserted into the human genome in infected cells

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10
Q

What can be done using PCR?

A

You can isolate viral genomes, or pieces of viral genomes, from infected patients

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11
Q

What can come from each patient with HIV?

A

Multiple sequences

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12
Q

What is shown on a phylogenetic tree of HIV patients?

A

The sequences are more closely related within a patient than between patients

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13
Q

What are the possible explanations of the patter of HIV genomes on a phylogenetic tree?

A

Infections from multiple viruses or the viruses are changing

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14
Q

What is meant by infections from multiple viruses?

A

Each patient may have more than one viral sequence because they were infected with multiple viruses

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15
Q

What is evidence for people having infections from multiple viruses?

A

Multiple sequences, infection from ‘bulk source’

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16
Q

What is evidence against people having infections from multiple viruses?

A

The pattern of the tree - of there were multiple infections, why are viruses within patients more similar than viruses between patients

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17
Q

What is meant by the viruses are changing?

A

The multiple sequences may be due to the viruses changing within a patient

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18
Q

What is evidence for the viruses changing?

A

Viruses within a patient are more similar than between. The pattern of the tree suggests a single point of entry of the virus and then diversification

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19
Q

What is evidence against the virus changing?

A

Patient 91 has virus in two parts of the tree

20
Q

What is the prediction for the virus changing?

A

If the viruses are changing then if we sample a patient successively then we should see different viral sequences occurring

21
Q

What are the two types of explanation for the HIV sequence changing?

A

Proximate - By what mechanism is the change occurring

Ultimate - What is causing the change

22
Q

What is a lentivirus?

A

A sort of retrovirus

23
Q

What type of genome does HIV have?

A

a RNA genome

24
Q

What does HIV do?

A

Infect and damage immune system cells

25
Q

What is reverse transcriptase?

A

An enzyme that turns RNA sequence back Ito NDA

26
Q

HIV sequence is RNA, but …

A

it is turned into DNA to insert into the human genome

27
Q

Reverse transcription is …

A

more error prone than DNA replication so lots of variants are formed

28
Q

Is it just a mutation?

A

The key is we do not find inactivating mutations, all the variants found encode active, working viruses. So is it evolution?

29
Q

What is required for natural selection?

A

Variation, inheritance, selection, time

30
Q

How does HIV show variation?

A

By the error-prone nature of HIV reverse transcription

31
Q

How does HIV show inheritance?

A

HIV viruses pass on their RNA after being inserted in the genome

32
Q

How does HIV show selection?

A

The immune system, drug regimen, changes in the receptor and tropism in tissues for or against the HIV variants

33
Q

How does HIV shoe time?

A

HIV lifecycle is very fast, so in the course of infection there is plenty of time for evolution

34
Q

How can it be tested if HIV evolves?

A

Changing the selective pressure or seeing if viruses evolve differently of you put. patient on anti-retroviral drugs

35
Q

What is seen when it is tested if HIV evolves?

A

AIDS viruses from patients on anti-retrovirals have a different pattern of variation from those that are not

36
Q

What is the most clear example of HIV evolving?

A

The advent resistance of viruses - first to AZT, now to ripple therapy or HAART (high active retroviral therapy)

37
Q

What does HIV hold the record for?

A

The fastest evolving thing we know of

38
Q

What do patients have?

A

The don’t have a virus, they have a vast armada of viral variants

39
Q

What arises rapidly?

A

Resistance to therapy, even complex therapy

40
Q

What is made hard by the rapid evolving of HIV?

A

Making effective vaccines

41
Q

How many provirus containing cells are in a HIV patient?

A

10^8 to 5x10^10

42
Q

What may each provirus containing cell be?

A

Genetically distinct, so assuming 1 provirus/cell we have up to 5x10^10 variants

43
Q

What do many pathogens do?

A

Evolve within the host in the same way as HIV

44
Q

What is also an evolutionary process?

A

The antimicrobial resistance spreading through a population

45
Q

What does our own genome evolve to?

A

In response to pathogens

46
Q

What can evolutionary thinking do?

A

Help us understand and better respond to pathogens like HIV

47
Q

Evolution is …

A

a key way that pathogens response to hosts and therapy

CELS191 (23 decks)

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