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RUSVM Virology > Effect of Virus on Host Cell > Flashcards

Effect of Virus on Host Cell Flashcards

1
Q

How do viruses interfere with cell membrane function

A

Promote cell fusion

Affect ion exchange and membrane potential

Induce synthesis of intracellular membranes

Damage cytoskeleton

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2
Q

Mechanism of Acutely Transforming RNA virus

A
  • Infection of cell with retrovirus and inetegration of proto-oncogene
  • Mutation causes proto-oncogene to become oncogene
  • Infection of new host cell
  • Integration and expresson of viral oncogene
  • Neoplastic transformation
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3
Q

Differentiation Antigens

A

Proteins associated with specific stages of cell differentiation

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4
Q

Neoplasia

A

Denotes an abnormal tissue overgrowth that may be either localized or disseminated it is the process that leads to the formation of neoplasms

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5
Q

Tumor Specific Antigens

A

Products of mutated oncogenes and tumor suppressor genes

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6
Q

All RNA tumor viruses belong to the family

A

Retroviridae

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7
Q

Most important oncogenic viruses in animals?

A

Retroviruses

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8
Q

Responsible for degradation of the cells own DNA and proteins during apoptosis

A

Caspases

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9
Q

Primary effect of virus on the host cell is due to

A

Viral replication and viral proteins that are toxic to the host cell

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10
Q

Oncogenic Papillomaviruses

A

Produce papillomas on the skin and mucous membranes of most animal species

Hyperplastic epithelial outgrowths that generally regress spontaneously

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11
Q

Acutely Transforming RNA Virus

A

Directly oncogenic by carring an additional viral oncogene (V-onc)

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12
Q

Examples of cytopathic effects

A

Cell lysis

Cell rounding

Cell detachment

Vacuoles in cytoplasm

Inclusion bodies

Syncytium formation

Antigenic changes in cell membrane

Swelling and clumping

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13
Q

Pyknosis

A

Degenerative condition of a cell nucleus marked by clumping of the chromosomes, hyper chromatism and shrinking of the nucleus

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14
Q

Membrane Fusion/ Surface Fusion only occurs in (enveloped/nonenveloped) viruses

A

Enveloped

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15
Q

Cytotoxic T lymphocytes and NK cells can initiate extrinsic apoptotsis pathway utilizing medatos such as

A

Perforin and Granzyme

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16
Q

Host cell genes that encode important cell signaling products that regulate normal cell proliferation

A

C-onc genes and Proto-oncogenes

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17
Q

Non cytocidal viruses typically cause ___________ infections.

A

Non cytocidal viruses typically cause persistant infections.

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18
Q

Oncogenic viruses

A

Viruses that cause or give rise to tumors

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19
Q

Oncogenes

A

Mutated forms of proto-oncogenes or aberrantly expressed proto-oncogenes

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20
Q

Types of Tumor Antigens

A

Differentiation Antigens

Mutated Proteins

Viral Coded Proteins

Excessive Amounts of Normal Protein

Cancer/Testis Antigens

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21
Q

DNA tumor viruses interact with the cell in what two ways

A

Productive infection in permissive cell resulting in cell lysis

Non productive infection in nonpermissive cell resulting in transformation of the cell

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22
Q

Benign Neoplasm

A

Growth produced by abnormal cell proliferation that remains localized and does not invade adjacent tissue

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23
Q

Cell Fusion

Syncytium or Polykaryon

A

Fusion of the plasma membrane of four or more cells to produce an enlarged cell with four or more nuclei

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24
Q

Tumor Suppressor Genes

A

Play a role in keeping cell division in check. Encodes proteins that regulate and inhibit uncontrolled growth

25
Q

Tumor Antigens

A

Antigens appear on the surface of tumor cells that may provoke an immune response

26
Q

Cytopathic Effect (Cytopathogenic Effect)

A

Damage or morphological changes to host cells during virus invasion

27
Q

Cancer/Testis Antigens

A

Proteins of unknown function

28
Q

Extrinsic (Death Receptor) Apoptotic Pathway

A

Activated by engagement of specific cell-membrane receptors which are members of the TNF receptor family.

29
Q

Encode proteins that inhibit cell proliferation by holding cell cycle at G1

A

Tumor Suppressor Genes

30
Q

Describe the mechanism of Oncoproteins of DNA Viruses

A
  • DNA damage stimulates p53
  • DNA Virus produces E6 to bind p53 to prevent p53 from making damaged cell undergo apoptosis
  • DNA Virus produces E7 to bind to Rb and prevent it from stopping damaged cells from growing
31
Q

Mechanism of Slowing Transforming RNA viruses

A
  • Infection of cell with RNA virus carrying promoter gene
  • Integration of promoter gene adjacent to proto-oncogene
  • Conversion of proto-oncogene to oncogene
  • Neoplastic Transformation
32
Q

Slow Transforming RNA Virus

A

Integration of RNA viral genes into host chromosomal DNA can occur at promotor or enhancer sites that drive the increase in proto-oncogene/c-onc gene expression leading to malignant transformation of the cell.

33
Q

Abnormal proteins that arise from mutations are classified as

A

Tumor Specific Antigens

Tumor Associated Antigens

34
Q

How do viruses inhibit host cell protein synthesis

A

Viral enzymes degrade cellular mRNAs

Produce factors that bind to ribosomes and inhibit cellular mRNA translation

Altering cellular environment to favor viral mRNA translation

Large excess of viral mRNA outcompetes host mRNA

35
Q

Malignant Neoplasm

A

Locally invasive and may also be srpead to other parts of the body - metastasis

36
Q

Cells divide in what phases

A

Mitosis and Meiosis

37
Q

Two mechanisms by which RNA viruses become oncogenic

A

Acutely Transforming

Slowly Transforming

38
Q

Secondary effect of virus on the host cell is due to

A

Metabolic needs of the virus

39
Q

Genes separated from the cellular machiner that normally control gene expression so they have power of unregulated expression

A

V-Onc Genes

40
Q

Oncology

A

Study of neoplasia and neoplasms

41
Q

Enhancer Gene

A

Transcriptional regulatory sequence located some distance from the promoter; increases the rate of initiation of transcription

42
Q

Promoter Gene

A

DNA Sequence at which DNA dependent RNA polymerase binds to initiate transcription

43
Q

Retinoblastoma Proteins (Rb)

A

Tumor suppressor gene

Phosphorylated form cannot bind E2F allowing cell cycle to progress

Un-Phosphorylated form binds to E2F holding cell cycle at G1 to S phase

44
Q

Effects of Viruses on Host Cells

A

Cytocidal

Non-Cytocidal

Cell transformation

45
Q

Characteristics of transformed (neoplastic) cells

A

Cells become more spindle shaped

Loss of contact inhibition

46
Q

How do viruses inhibit host cell mRNA production and processing

A

Decreases the availability of transcription factors required for RNA polymerase activity

Inhibit polyadenylation and splicing of host cell primary mRNA transcripts required to form mature RNA

47
Q

Oncoviruses generally have what type of genome

A

DNA

48
Q

Proto-oncogenes

A

Encode protein that function in normal cellular growth and differentiation

49
Q

Inclusion Bodies

A

Abnormal structure in the cell nucleus or cytoplasm or both. Such aggregates of proteins having characteristic staining properties and associated with certain viral infections

50
Q

Regulators of the cell cycle

A

Proto-oncogenes

Tumor suppressor genes

51
Q

Tumor Associated Genes

A

Products of other mutated genes

52
Q

Apoptosis

A

Process of programed cell death, which is essentially a mechanism of cell suicide that the host activates as a last resport to eliminate viral factories before progeny virus production is complete

53
Q

Neoplasm

A

Arise as a consequence of the dysregulated growth of cells derived from a single, genetically altered progenitor cell

54
Q

Metastasis

A

Spread of cancer from the part of the body where it started to other parts of the body

55
Q

Role of cytotoxic T lymphocytes in the extrinsic apoptotic pathway

A
  • Recognize virus infected cells in antigen specific manner can bind the Fas Receptor
  • Activate death domain
  • Trigger executioner caspase pathway
  • Eliminate cell before becoming fuctional virus factory
56
Q

Intrinsic (Mitochondrial) Apoptotic Pathway

A

Activated as a result of increased permeability of mitochondrial membranes subsequent to cell injury

57
Q

Cytopathic Effects on host cells can be

A

Complete destruction of cells

Subtotal destruction of cells

Focal distruction of cells

58
Q

Cell transformation

A

changing of a normal cell into a cancer cell

RUSVM Virology (35 decks)

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