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LS10 C.elegans > Virology > Flashcards

Virology Flashcards

1
Q

what are viruses?

A

Obligate parasites that can function only after they replicate in a cell

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2
Q

Viruses depend on their host to survive because:

A

If viruses are too successful and quickly kill their hosts, they immediately eliminate themselves too e.g. omicron

If viruses are too passive and the host can stop their growth, then they also eliminate themselves

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3
Q

Name 3 different phases withing a virus (LEM)

A

Eclipse phase, here there are no viral particles yet

Maturation phase, here only cell-associated viruses are present

Latent phase, the release of the virus

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4
Q

The genetic material is surrounded by:

A

a protein capsid (helical or icosahedral)

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5
Q

What is the function of a capsid?

A

Protecting nucleic acids from chemical, physical and enzymatic damage

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6
Q

Why do viruses only use a limited number of designs?

A

Because it requires less genetic material because it repeats

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7
Q

How many subunits does a isohedrical capsid have?

A

60

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8
Q

Metastability =?

A

the ability of a non-equilibrium state to hold for a long time

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9
Q

Whats the difference between naked and eveloped viruses?

A

Naked viruses are composed of only the nucleocapsid and enveloped viruses have a layer of plasma membrane taken from the host cell that surrounds the nucelocapsid

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10
Q

Whats the function of spikes?

A

They add to the attachment of the virus to a host cell membrane

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11
Q

Host range =?

A

it defines the number of host species used by a pathogen

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12
Q

Whats the difference between specialists and generalists?

A

Specialists infect a limited amount of hosts and generalists infect a large range of hosts

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13
Q

Whats the difference between specialists and generalists?

A

Specialists infect a limited amount of hosts and generalists infect a large range of hosts

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14
Q

Tissue tropism =?

A

The different cell types that can be infected by the virus

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15
Q

a resistant cell has:…

A

no entry receptor, the the cell may or may not be able to support the viral replication

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16
Q

A susceptible cell has…

A

a functional receptor for a given virus, so the cell may or may not support viral replication

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17
Q

A permissive cell can…

A

replicate the virus, but may or may not be susceptible

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18
Q

A susceptible and permissive cell can…

A

take up a virus particle and replicate it

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19
Q

Primary cells…

A

are prepared directly from an animal or human tissue (can be subcultered)

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20
Q

Semi-coninuous diploid cells…

A

are derived from human fetal tissue

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21
Q

Continuous cells…

A

are derived from tumors of human or animal tissue

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22
Q

Name 4 quantification methods (pfvt)

A

Plaque assay, fluorescent focus assay, virus in cell culture and TCID50

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23
Q

Multiplicity of infection (MOI) = ?

A

the number of indectious particles added per cells

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24
Q

Name 6 physical measurements of virus particles

A

Heamagglutination assay, haemagglutination inhibiton assay, EM, ELISA, flowcytometry, and antigen rapid test

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25
Q

Name the 6 steps of the viral life cycle:

A

attachment, penetration, uncoating, biosynthesism assembly and release

26
Q

What happens during attachment?

A

The virus adheres to the cell surface by electrostatics and attaches to a receptor molecule on the cell surface

27
Q

What happens during penetration?

A

The virus is endocytosed or fuses with the host cell membrane

28
Q

What happens during uncoating?

A

The capsid is degraded either in the cytoplasm or in the endocytic vesicle

Uncoating is triggered by the host cell enzymes

29
Q

Name 4 modes of nuclear entry:

A

through pores, docking at pores, pushing with motor tubules or by disrupting the nuclear membrane

30
Q

How to T4 bacteriophages target the bacteria?

A

By penetrating the cell with a needle and injecting their particles inside the cell

31
Q

Name 3 modes of assembly:

A

self-assembly, with the help of scaffolding proteins or by precursor proteins for proteolytic cleavage

32
Q

Name 2 modes of release

A

by budding of the plasma membrane (enveloped viruses) or by cell lysis

33
Q

What happens during maturation?

A

Virus become infectious by proteolytic modifications to the capsid or envelope

34
Q

Name 2 important events that happen after infection:

A

procution of virus structural proteins and enzymes, and replication of the viral genome

35
Q

Why do all viral genomes must make mRNA?

A

So that the host ribosomes can read the viral genome

36
Q

Whats the difference between + strand mRNA and - strand mRNA

A

+ strand has the same polarity as mRNA and - strand is complementary to the + strand and can not be translated

37
Q

Where does the poxyvirus replicate?

A

In the cytoplasm and brings its own DNA and RNA enzymes

38
Q

What is needed for DNA synthesis?

A

DdDp and primers

39
Q

Why is RNA more prone to mutations compared to DNA

A

Because RdRp has no proofreading comared to DdDp

40
Q

Antigenic drift =?

A

minor point mutations where the immune system no longer recognizes hemagglutinin and HA/NA proteins

41
Q

Antigenic shift=?

A

A sudden and major change in surface antigens when 2 different strains inject the same cell at the same time and undergo genetic reassortent

42
Q

Why is antigenic shift so dangerous?

A

Because the change is so drastic that it can cause pandemics or outbreaks because the virus is so new and barely anyone has any prior immunity to it

43
Q

Viral virulence =…

A

The capacity of a virus to cause disease in a host

44
Q

Clinical signs=…

A

Attributes of infection that are objectively measured e.g. rash, body temperature

45
Q

Clinical symptoms=…

A

Attributes of infection that are subjectively assessed e.g. pain or soreness

46
Q

Incubation period =…

A

The initial period before symptoms of disease are obvious

47
Q

When can a virus enter an entire organism?

A

When there is sufficient virus particles present, cells at the primary site of infection must be accessible, susceptible and permissive, and the host immune system must be absent

48
Q

Name 4 ways a virus can be present/spread in the host

A
  1. . Localized, so the virus stays at the primary site
  2. Dissemination, it spreads from the primary site
  3. Viremia, it is present in the blood
  4. Systemic, it spreads to multiple susceptible organs
49
Q

Acute infection…

A

Sudden onset/short time infection

50
Q

Subclinical infection…

A

Same as acute but there are no signs of symptoms present

51
Q

Persistent infections…

A

Infect a few cells and produce low level of progeny

52
Q

Chronic infections..

A

more active and have a larger yield

53
Q

Latent infections…

A

Always start acute/subclinical and you have flare-ups of the disease

54
Q

Slowly progressive infections…

A

Takes many years to manifest, virus particles are still produced

55
Q

Virus-induced tumors…

A

Viruses induce transformation of genetic materual e.g. HPV

56
Q

How can a virus leave the host body?

A

Through following the route of entry, sneezing, nasal secretions, feces, sperm etc.

57
Q

Horizontal transmission:

A

between members of the same species, or different species (zoonotic), or via intermediate species that carry the virus

58
Q

Vertical transmission

A

the transfer of infection between mother and child

59
Q

Iatrogenic

A

by the activity of a health care worker e.g. injection

60
Q

Nosocomial

A

while in the hospital or health care facility

61
Q

Germline transmission

A

proviral DNA is transmitted as part of the genome

62
Q

R-0 =….

A

number of secondary infections that can arise in a population of susceptible hosts from a single infected individual

LS10 C.elegans (4 decks)

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