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Biology 416 VIROLOGY > The Infectious Cycle and Viral Diagnostics > Flashcards

The Infectious Cycle and Viral Diagnostics Flashcards

1
Q

What is virus reproduction?

A

The sum total of all events that occur during the infectious cycle

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2
Q

What is the one-step growth curve?

A

A single reproduction cycle that occurs synchronously in every infected cell

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3
Q

What is a susceptible cell?

A

A cell that provides the receptors required for virus entry

Has a functional receptor for a given virus

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4
Q

What is a permissive cell?

A

A cell that is able to support virus reproduction when viral nucleic acid is introduced

Virus can be reproduced in a permissive cell

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5
Q

What is a monolayer?

A

A layer of cultured cells growing in a cell culture dish

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6
Q

What are primary-cell cultures?

A

Cell cultures prepared from animal tissues

These cultures include several cell types and have a limited life span usually no more than 5 to 20 cell divisions

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7
Q

What are continuous cell-lines?

A

Cultures of a single cell type that can be propagated indefinitely in culture

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8
Q

What are cytopathic effects?

A

The morphological changes induced in cells by viral infection

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9
Q

What is a virus titer?

A

The concentration of a virus in a sample

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10
Q

What are plaque-forming units (PFU) per milliliter?

A

A measure of virus infectivity

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11
Q

What is hemagglutination?

A

The linking of multiple red blood cells by virus particles resulting in a lattice basis of method to measure virus concentration

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12
Q

What is the eclipse period?

A

phase in which infectivity is lost when virions are disassembled after penetrating cells

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13
Q

What is the latent perioid?

A

how long it takes virus to get out of the cells once it is made

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14
Q

What is the multiplicity of infection?

A

number of infectious particles ADDED per cell

Formula:
MOI = Amount of virus (PFU) / # of cells

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15
Q

What are the 5 key steps to the viral infectious cycle ?

A
  1. Attachment and entry
  2. Translation
  3. Genome replication
  4. Assembly
  5. Release

Photo on chapter 3

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16
Q

What are two conditions that need to be satisfied to have a successful viral reproduction?

A

The cell HAS to be susceptible and permissive

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17
Q

What is the ONLY cell in which a virus can enter and be reproduced?

A

A susceptible and permissive cell

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18
Q

Are the infectious cycle and virus reproduction synonymous?

A

Yes (synonymous = same)

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19
Q

How do you know a cell has been infected with virus?

A

If they are susceptible and permissive, they will likely show CYTOPATHIC EFFECTS

Though, not ever cell will show cytopathic effects

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20
Q

What is a syncytia?

A

Large multinucleate cells

Multiple cell fusions of uninuclear cells

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21
Q

How is syncytia formed?

A

Syncytium formation is induced by viral infection

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22
Q

What are some virus examples of syncytia?

A 
Herpesvirus
Paramyxovirus
Poxvirus
Reovirus
Retrovirus
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23
Q

What is the American Type Culture Collection (ATCC)?

A

A nonprofit organization

Established in 1925

Collects, stores, and distributes materials for R&D. These reference microorganisms and cell lines of any tissues.

Distributes to >150 countries

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24
Q

What is an organoid?

A

3D structures derived from STEM CELLS that maintain identity of organ being studied

An advancement in cell culture

25
Q

What can organoids be used for? (applications)

A 
Disease mechanism
Toxicology
Development and stem cell biology
Regenerative medicine
Drug discovery
Infectious disease
26
Q

What are the differences between bacterial and viral reproduction?

A

Bacterial reproduction has an exponential growth

Viral reproduction has a eclipse period and a burst period

27
Q

What is a burst period?

A

One virus yields multiple viruses

28
Q

What is a intracellular?

A

Infectious virus found WITHIN cells

29
Q

What is a extracellular?

A

Infectious virus found within the SUPERNATANT of cells

30
Q

How do scientists cultivate (grow) viruses?

A

Cell culture

Laboratory animals

Embryonated eggs

31
Q

What cytopathic effects would be visible by conventional light microscopy?

A

Rounding up and detachment of cells from culture dish

Cell lysis

Welling of nuclei

Syncytium formation

32
Q

On average, how long does it take to make a vaccine in chicken eggs?

33
Q

Who was Henrietta Lacks and why was she significant?

A

An African American woman who died in the early 1950s from cancer and whose cells provided the world’s first and still widely used continuous cell lines

34
Q

What vaccine was tested in HeLa cells by Jonas Salk in the 1950s?

35
Q

What is plaque assay?

A

Determines virus titer, the concentration of virus in sample

36
Q

Where and when was plaque assay modified?

A

Modified in 1952 by Renato Dulbecco in animal virology

37
Q

What technique is used for plaque assay?

A

The monolayer of cultured cells + virus with the addition of nutrient medium + supplement agar will result in plaque formation.

38
Q

Describe plaque formation

A

Circular zone of infected cells

Dyes may enhance contrast

39
Q

How is the virus titer from a plaque assay measured?

A

Measured in plaque forming units (PFU) / mL

10x fold dilutions

0.1mL aliquots of virus inoculated onto susceptible cells

40
Q

What is the formula for determining virus titer?

A

(plaque count)(virus dilution)(10)

41
Q

What is the distribution of virus particles per cell in MOI?

A

Poisson Distribution (bell shaped curve)

P(k) = e^-mm^k/k

P(k) = fraction of cells infected by k virus particles

e^-m = 1/e^m

42
Q

What is the starting RTPCR covid test material?

A

RNA because covid-19 is a RNA virus

43
Q

What does IgM show?

A

IgM shows early infection

44
Q

What does IgG show?

A

IgG shows long term infection

things you’ve have and past through, etc

45
Q

What are biological ways to detect viruses?

A

Plaque Assay

46
Q

What are physical ways to detect viruses?

A

Hemagglutination

Imaging virus particles

  • Electron Microscopy
  • Live-cell imaging of fluorescent virions

Serology

  • Immune components in the blood
  • ELISA

Nucleic Acids
- PCR, RTPCR, deep sequencing

47
Q

What are the protein components of the immune system?

A

2 light chains, 2 heavy chains

48
Q

What are antibodies made of?

A

Made by B cells

49
Q

What are the 5 types of antibodies that circulate in the blood?

A

IgA, IgD, IgE, IgG, and IgM

50
Q

What do antibodies do?

A

Recognizes antigens and neutralizes them

51
Q

What is an antigen?

A

any foreign substance (virus, bacteria, sometimes your own body (autoimmunity))

52
Q

What does enzyme-linked immunosorbent assay (ELISA) detect?

A

With a second antibody and a captured antibody, detects viral proteins in sample

With anti-IgG, detect antibodies in sample

53
Q

What is lateral flow immunochromatographic assay?

A

Modification of ELISA

Used in rapid antigen detection test kits

  • Pregnancy: human chorionic gonadotropin (HCG)
  • Sample: urine or blood
54
Q

What are the steps in COVID-19 rapid serology antibody test of the lateral flow immunochromatographic assay?

A
  1. Sample loading
  2. Buffer loading
  3. Sample incubation
  4. Antibody-antigen recognition
  5. COVID-19 antibody detection
  6. Control antibody detection
  7. Interpreting results
55
Q

What is the RT-PCR princple?

A
  1. Denaturation
  2. Primer annealing
  3. Extension
56
Q

What is the threshold line in RT-PCR?

A

reaction reaches fluorescent intensity above background levels

57
Q

What is the copy threshold (Ct)/copy quantification (Cq) value?

A

PCR cycle number where sample reaction curve intersects threshold line

58
Q

What is environmental/deep sequencing?

A

Simultaneous sequencing of thousands to millions of DNA molecules

59
Q

What are applications of deep sequencing?

A

Virus discovery

Genome organization

Evolution (phylogenetic relationships)

Biology 416 VIROLOGY (7 decks)

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