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biol 115 > Module 1; lecture 6, virulence and transmission > Flashcards

Module 1; lecture 6, virulence and transmission Flashcards

1
Q

How is soap and hand sanitizer different

A

Since we are physically applying pressure in the process of washing hands, things just get off of our hands and washed away with water.
Acts in a number of different ways, Different from hand sanitizer bcs it gets washed off

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2
Q

Viruses and bacteria need what?

A

HOSTS

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3
Q

Types of transmission?

A

1.Direct Transmission
2.Droplet transmission
3.Indirect transmission

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4
Q

Whether its direct/indirect is going to affect how ______

A

Virulent a virus or bacteria is ( A balancing art)

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5
Q

Virulent?

A

How much the virus/bacteria affects the host’s fitness

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6
Q

What is direct transmission, give examples?

A
  • Person to person contact- transmission that results from coming into contact with another person( or their body fluids).
    -Examples; Sexually transmitted viruses like HIV and other bloodborne viruses like Ebola.
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7
Q

What is droplet transmission, give example

A
  • When one host accidentally sneezes on another.
  • Examples; like influenza and covid19
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8
Q

What kind of droplets go the furthest?

A

Larger droplets don’t go as far as smaller ones, airborne droplets go very far

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9
Q

What is indirect transmission,give 3 known phenomenons of this?

A

Vector transmission getting picked up by a carrier and carried to a new host. Or airborne transmission or waterborne transmission, person who has the virus isn’t necessarily present
For example, Malaria is transmitted this way

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10
Q

airborne transmission

A

Is indirect for example, dust particles can sometimes have viruses and survive longer/be infectious even if infected person is not there. ( chickenpox, measles for example)

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11
Q

vector transmission

A

Getting picked up by a carrier( mosquitos= malaria transmitted this way, yellow fever too)

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12
Q

Waterborne transmission

A

Leaving one host( ex in feces), infecting the water supply, and being taken up (ex in drinking water) by a new host.
ex; Cholera is transmitted this way

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13
Q

We can think of virulence as what ?

A

Reproductive output: We can think of virulence as the reproductive output of the virus or bacteria.

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14
Q

Which strains create more offspring?

A

Highly virulent strains create more offspring than less virulent ones.

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15
Q

What is the balancing art?

A

Balancing art ( Transmission vs virulence) because the viruses who make the ppl very sick makes them stay home, makes them less fit to be out and spreading the virus vs less virulent less damage so people easily spread this.

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16
Q

What is natural selection’s role in this?

A

Natural selection should favor viruses and bacteria that achieve a balance between— how severe the disease they cause is ( virulence pathogenicity)—and how easy it is for hosts to catch it ( Transmissibility )

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17
Q

The Fitness of a virus/bacteria depends on what?

A

Depends on how virulent and transmission it is.

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18
Q

examples of opposite examples

A

Cholera is more virulent, Sexually transmissible is less virulent (HIV)

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19
Q

Three major kinds of viruses

A

1.Flu viruses ( H1N1, the 1918 spanish flu)
2.Filamentous viruses ( hemorrhagic fever viruses like ebola)
3.Coronaviruses ( COVID19, SARS, MERS)

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20
Q

Similarity between 3 viruses?

A

Each associated with immune responses that go haywire and do damage to the host.

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21
Q

Explain the H1N1 virus

A

Example of antigenic shift involving viruses from three species ( pig, bird, human) : These combined to create w new H1N1 virus with parts of a viruses from multiple species.

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22
Q

The H1N1 virus is also known as what

A

The swine flu

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23
Q

Why did the H1N1 cause such a panic?

A

Because we knew from experience that these antigenic shifts created rapid big changes and our immune systems would be unable to recognize them because they are such big changes. We didn’t have any immunity to it because it it was a virus from another species.
So there was a potential that it could be highly virulence, also didn’t know how transmissible the virus was going to be
Turned out to be highly transmissible but not highly virulent.

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24
Q

Explain the spanish flu

A
  1. Virus was strange for a number of reasons ;
    - There were three waves of infection, very close together in time (pandemic with three phases) —> Second wave was the most deadly ; weird because you might expect greater immunity during second wave but instead we saw more deaths…
    - It did not just disappear, turns out it is the ancestor of all seasonal and pandemic flu over the last century. - Then, the virus gained small mutations through antigenic drift ( so our immune systems figured out how to deal with virus)
    - Gave that flu to pigs, it adapted to pigs and became a swine flu, seen every year in pigs around the world
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25
Q

Stats of the spanish flu

A

infected 500 million people and killed 50-100 million people, -2.5% of the world’s population at the time

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26
Q

What is the craziest part of the spanish flu?

A

The swine flu swapped genes with a different bird flu and different human flu and became the 2009 H1N1 pandemic.

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27
Q

Who died of spanish flu the most?

A

Healthy young adults who died the most ( most flus kill either the very young or the elders= the ones with weaker immune systems)

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28
Q

Effects of spanish flu ?

A

Effects of the virus were really rapid ( out and about to death in matter of hours = Disease both highly transmissible AND highly virulent)

29
Q

How lethal is Ebola? How virulent is it?

A

Ebola is lethal in 70-90 % of cases of infection (highly virulent)

30
Q

Who are the hosts of filamentous or filoviruses viruses ? Explain why?

A

Filoviruses or filamentous viruses, host appear to be the bat = bats serve as a reservoir for the virus.
- Because bats have developed some immunity, the virus co-exists with them without killing them (commensalism) = Also means that in bats, the virus isn’t rapidly changing.

31
Q

How do these viruses spread?

A

because bats interact with other animals, who potentially could interact with humans ( apes, deers ), who then interact with humans who then interact with other humans.

32
Q

What are the early vs late symptoms of Ebola like?

A

Early symptoms in humans are like a bad case of the flu
VS
Late symptoms are different story, they are terrible, called hemorrhagic because it gives you big rashes that contain blood. = immune system goes haywire and cant combat infection.

33
Q

Ebola, swift and lethal, but why was the 1918 flu so successful then because it was also swift and lethal…?

A

The difference is in transmission, ebola require close contact with body fluids = it is difficult to catch.

33
Q

Why are ebola effects hemorrhagic, why does this happen?

A

Ebola infects macrophages, part of our immune system = Infected macrophages releases cytokines ( this increases the permeability of blood vessels —> allowing blood to leak out of them)

34
Q

But if ebola isn’t easily contagious, how did this happen in 2014 ( series of outbreaks in africa) ?

A

transmission can be shaped by the social environment and infrastructure. This is an example of this.
In 2014, ebola epidemic was much bigger than previous outbreaks because it happened in more densely populated urban areas.

35
Q

What happened in Nigeria because they escaped and didn’t get many cases but were also densely populated

A

LUCK; Their first case of ebola was put into quarantine immediately, so outbreak was stopped ( doctor who recognized sickness actually died of ebola later on, super sad)

36
Q

Coronaviruses are a diverse family of viruses what are they named for?

A

Named for the “spikes” on their surface, look like crowns; spike proteins let in the virus bind to the surface of cells so that cells let them in.

37
Q

What are the hosts of corona viruses?

A

Different hosts (rodents or bats), they infect intermediate hosts(cows for example) which would then infect humans…

38
Q

How is Coronaviruses transmitted?

A

Transmitted through respiratory droplets ( this is where the magical number of 2 meters comes from)

39
Q

What happens in some cases with corona virus?

A

Can trigger “cytokine storm”
1. With covid19, the “brakes” for the immune system stop working= affecting multiple systems ( brain, heart, gastrointestinal tract, kidneys, liver & circulatory system)

40
Q

Symptoms and effects of the coronavirus?

A

Infects the epithelial cells in the lungs— symptoms are similar to mild to severe cases of pneumonia.

41
Q

An outbreak

A

Often sudden increase in cases of a disease above what is usually expected based on recent experiences

42
Q

An epidemic

A

Is when the outbreak goes beyond a small or restricted area

43
Q

A Pandemic

A

Is an epidemic that has spread through a large region, for example multiple continents or worldwide.

44
Q

An Endemic

A

When a disease is consistently present in a particular region. This makes the disease spread and rates predictable.

45
Q

Our relationship with viruses is more complicated how?

A

Our interactions with them over millions of years has resulted in additions and translocations to human DNA
- Viral infections have influenced human evolution

46
Q

Viruses are extremely adaptable how?

A
  1. Relatively simple construction: Made up of two- or three parts**
    Viral genome ( can be rna or dna)
  2. Short Generation time
    3.High mutation rates

Viruses don’t replicate on their own, they use the machinery from the host cell & they require fewer genes & proteins because they don’t have to build their own machinery.
They are also NOT ALIVE.

47
Q

Can viruses have DNA & RNA?

A

-Sometimes there are proteins to keep the RNA and DNA organized and easy to copy, but not always ( so they can contain DNA OR RNA)
- RNA and DNA are found inside a protein coat or capsid ( sometimes the capsid is inside an envelope)

48
Q

True or false; All viruses have the same overall construction but there a huge diversity of the kind of viruses

A

True

49
Q

What do viruses vary in

A

Structure, surface proteins, effects on the host.

50
Q

Surface proteins

A

Allow entry into host cells

51
Q

Proteins are also _______

A

Proteins are also often how the immune system recognizes a virus.

52
Q

DIfferent types of proteins are________

A

“keys” to different types of cells.

53
Q

How do they reproduce quickly?

A

DNA/RNA comes in small packets, easily picked up and quickly transcribed ( copied) or incorporated into the host genome = reproduce quickly.

54
Q

high mutations rates are especially true in what kind of viruses and why?

A

Especially true in RNA viruses,
why? Proteins that copy RNA ( polymerases) lack proof-reading ability— means there are more frequent errors during copying, this can lead to mutations.
- This can make it difficult to develop vaccines ( because the genetic sequence is always changing)

55
Q

Evolutionary changes to surface proteins can

A
  • Affect how well the virus enters a cell
  • Affect how well the immune system recognizes a virus.
56
Q

True or false.. How well a virus can evade immune response will depend how rapidly its changing those surface proteins to be able to still gain entry upon cells but still evade the responses of the immune system.

A

True

57
Q

Virus evolution

A

They evolve in 2 ways.
1. Antigenic Drift: In their host species viruses can undergo slow or limited evolution.

58
Q

Antigenic drift

A

when small changes in the virus that occur gradually through the accumulation of mutations.

59
Q

Antigenic shift

A

Large, abrupt changes that occur, often because a cell has been infected by multiple viruses, for example viruses from more than one species.

60
Q

Can a virus undergoing antigenic drift cause an epidemic or pandemic?

A

Probably not because the idea is that we’ve been interacting with that virus pretty frequently, lwe have some resistance to it, our immune system can recognize it, so its possible those small mutations could lead to our immune system being briefly baffled but the immune system will still quickly learn to balance it again…

61
Q

Can a virus that has just undergone an antigenic shift be endemic?

A

Endemic means consistently present in a particular location, endemic viruses under going antigenic drift if anything

62
Q

Influenza virus subtypes are based on what surface proteins

A

Influenza virus subtypes are based on two surface proteins: Hemagglutinin ( H) and neuraminidase (N).

63
Q

Hemagglutinin

A

is important for binding and selectivity, it is the “key” to the cells “lock” from the video

64
Q

how many different hemagglutinin

A

16 different hemagglutinins

65
Q

Neuraminidase

A

Important to let new copies of the virus out of the cell so they can infect other cells

66
Q

How many different neuraminidase?

A

9 different neuraminidases

67
Q

ex H1N1 just means what ?

A

hemagglutinin 1 & neuraminidase 1

68
Q
A

biol 115 (8 decks)

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