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Virology > Effects-Responses (Ex1) > Flashcards

Effects-Responses (Ex1) Flashcards

1
Q

What is Cytopathic effect?

A

damage or morphological changes to host cells during virus invasion

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2
Q

What are some Cytopathic effects?

A 
- complete destruction of cells
(all cells shrink, become dense, and detach from glass)
- subtotal destruction of cells
(detachment of some cells)
- focal destruction of cells
(localized areas of infection)
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3
Q

What is Pykonosis?

A

a degenerative condition of a cell nucleus marked by clumping of the chromosomes, hyperchromatism, and shrinking of the nucleus

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4
Q

Explain Cell Fusion

A
  • fusion of plasma membranes of four or more cells
  • fusion of infected cell with adjacent infected or non-infected cells
  • prone to premature cell death
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5
Q

General Mechanisms of Virus-Induced Cell Injury and Death (4)

A
  • inhibition of host-cell nucleic acid synthesis
  • inhibition of host-cell RNA transcription
  • inhibition of host-cell protein synthesis
  • interference with cellular membrane function
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6
Q

Describe the Intrinsic Pathway of apoptosis

A
  • Mitochondrial pathway

- activated as a result of increased permeability of mitochondrial membranes

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7
Q

Describe the Extrinsic Pathway of apoptosis

A
  • Death receptor pathway

- activated by engagement of specific cell membrane receptors

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8
Q

What is Cell Transformation?

A

the changing of a normal cell into a cancer cell

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9
Q

What is Neoplasia?

A

denotes an abnormal tissue overgrowth that may be either localized or disseminated

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10
Q

What is a Malignant Neoplasm?

A

locally invasive and may also spread to other parts of the body
- cancer

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11
Q

What are Oncogenic Viruses?

A

viruses that cause or give rise to tumors

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12
Q

What do Proto-oncogenes do?

A
  • encode proteins that function in normal cellular growth and differentiation
  • often involved in growth signaling and anti-apoptotic pathways
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13
Q

What are Oncogenes?

A
  • mutated forms of proto-oncogenes

- function in an unregulated manner

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14
Q

What happens to a DNA tumor virus when it enters a permissive cell?
Non-permissive cell?

A

P: virus completes its replication cycle, and releases progeny virions
NP: virus does not complete replication, transforms the cell into cancer cell

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15
Q

Describe Retinoblastoma Protein

A
  • un-phosphorylated Rb is active, and binds to transcription factor E2F, stopping cell division
  • phosphorylated Rb is inactive, and releases E2F from its inhibition
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16
Q

What is the function of p53 Protein?

A

looks for cells with genetic defects and makes them undergo apoptosis

17
Q

How do papillomas become malignant?

A
  • integration of viral genome into host DNA disrupts viral repressor gene E2
  • E6 and E7 are not regulated, so they cause the malignant transformation
18
Q

Acutely Transforming Retrovirus

A
  • host proto-oncogene becomes integrated into the viral DNA (v-onc)
  • no longer paired with suppressor gene, there is no regulation
19
Q

Slow/Chronic Transforming Retrovirus

A
  • integration of viral genome at promoter or enhancer sites

- increase proto-oncogene expression

20
Q

How do Innate Immune cells respond when their PRRs attach to PAMPs?

A
  • express IFNs or cytokines
  • activate phagocytic cells and endothelial cells with increased production of inflammatory mediators and expression of adhesion molecules
  • macrophages initiate chemotaxis, bringing in neutrophils
21
Q

Actions of Type-1 Interferons

A
  • inhibit protein synthesis and DNA replication
  • increase MHC 1 expression
  • activate NK cells
  • maturation of dendritic cells
  • stimulate memory T cell proliferation
22
Q

Actions of Type-2 Interferons

A
  • immunoregulatory
  • macrophage activation
  • isotype switching
  • development of TH1 effector cells
  • increased MHC expression
23
Q

Action of Type-3 Interferons

A
  • immunoregulator
24
Q

Describe Gene Silencing

A
  • RNA is chopped into small pieces called short interfering RNA
  • RNA-silencing complex is formed, containing endonuclease
  • parts of the mRNA that are complementary to the RNAi bind, and are chopped off by the endonuclease
  • so no protein synthesis and replication stops
25
Q

What is virus neutralization?

A

antibodies prevent virus attachment and entry into host cells

26
Q

What is opsonization?

A

antibodies coat the virions so they are recognized and phagocytosed by macrophages

27
Q

What happens in Antibody-Dependent Cell-Mediated Cytotoxicity?

A
  • antibodies bind to viral antigens expressed on surface of host cells
  • host cells destroyed
28
Q

What is Antigen Plasticity?

A
  • rapid changes in the structure of the viral antigen
  • virus may become resistant to immunity
  • antigenic drift, shift
29
Q

What is Antigen Multiplicity?

A
  • antigenic variants with little or no cross-reactivity

- multiple serotypes, immunity may not work against all of them

30
Q

What is Negative Cytokine Regulation?

A
  • blocking interferon receptor signal
  • virokines: homologs of cytokines produced by virus
  • viroreceptors: homologs to cytokine receptors, act as competitive antagonist

Virology (15 decks)

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