Effect of Virus on Host Cell

Question 1

How do viruses interfere with cell membrane function

Answer 1

Promote cell fusion

Affect ion exchange and membrane potential

Induce synthesis of intracellular membranes

Damage cytoskeleton

Question 2

Mechanism of Acutely Transforming RNA virus

Answer 2

• 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

Question 3

Differentiation Antigens

Answer 3

Proteins associated with specific stages of cell differentiation

Question 4

Neoplasia

Answer 4

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

Question 5

Tumor Specific Antigens

Answer 5

Products of mutated oncogenes and tumor suppressor genes

Question 6

All RNA tumor viruses belong to the family

Answer 6

Retroviridae

Question 7

Most important oncogenic viruses in animals?

Answer 7

Retroviruses

Question 8

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

Answer 8

Caspases

Question 9

Primary effect of virus on the host cell is due to

Answer 9

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

Question 10

Oncogenic Papillomaviruses

Answer 10

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

Hyperplastic epithelial outgrowths that generally regress spontaneously

Question 11

Acutely Transforming RNA Virus

Answer 11

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

Question 12

Examples of cytopathic effects

Answer 12

Cell lysis

Cell rounding

Cell detachment

Vacuoles in cytoplasm

Inclusion bodies

Syncytium formation

Antigenic changes in cell membrane

Swelling and clumping

Question 13

Pyknosis

Answer 13

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

Question 14

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

Answer 14

Enveloped

Question 15

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

Answer 15

Perforin and Granzyme

Question 16

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

Answer 16

C-onc genes and Proto-oncogenes

Question 17

Non cytocidal viruses typically cause ___________ infections.

Answer 17

Non cytocidal viruses typically cause persistant infections.

Question 18

Oncogenic viruses

Answer 18

Viruses that cause or give rise to tumors

Question 19

Oncogenes

Answer 19

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

Question 20

Types of Tumor Antigens

Answer 20

Differentiation Antigens

Mutated Proteins

Viral Coded Proteins

Excessive Amounts of Normal Protein

Cancer/Testis Antigens

Question 21

DNA tumor viruses interact with the cell in what two ways

Answer 21

Productive infection in permissive cell resulting in cell lysis

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

Question 22

Benign Neoplasm

Answer 22

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

Question 23

Cell Fusion

Syncytium or Polykaryon

Answer 23

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

Question 24

Tumor Suppressor Genes

Answer 24

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

Question 25

Tumor Antigens

Answer 25

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

Question 26

Cytopathic Effect (Cytopathogenic Effect)

Answer 26

Damage or morphological changes to host cells during virus invasion

Question 27

Cancer/Testis Antigens

Answer 27

Proteins of unknown function

Question 28

Extrinsic (Death Receptor) Apoptotic Pathway

Answer 28

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

Question 29

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

Answer 29

Tumor Suppressor Genes

Question 30

Describe the mechanism of Oncoproteins of DNA Viruses

Answer 30

* 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

Question 31

Mechanism of Slowing Transforming RNA viruses

Answer 31

* 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

Question 32

Slow Transforming RNA Virus

Answer 32

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.

Question 33

Abnormal proteins that arise from mutations are classified as

Answer 33

Tumor Specific Antigens Tumor Associated Antigens

Question 34

How do viruses inhibit host cell protein synthesis

Answer 34

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

Question 35

Malignant Neoplasm

Answer 35

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

Question 36

Cells divide in what phases

Answer 36

Mitosis and Meiosis

Question 37

Two mechanisms by which RNA viruses become oncogenic

Answer 37

Acutely Transforming Slowly Transforming

Question 38

Secondary effect of virus on the host cell is due to

Answer 38

Metabolic needs of the virus

Question 39

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

Answer 39

V-Onc Genes

Question 40

Oncology

Answer 40

Study of neoplasia and neoplasms

Question 41

Enhancer Gene

Answer 41

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

Question 42

Promoter Gene

Answer 42

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

Question 43

Retinoblastoma Proteins (Rb)

Answer 43

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

Question 44

Effects of Viruses on Host Cells

Answer 44

Cytocidal Non-Cytocidal Cell transformation

Question 45

Characteristics of transformed (neoplastic) cells

Answer 45

Cells become more spindle shaped Loss of contact inhibition

Question 46

How do viruses inhibit host cell mRNA production and processing

Answer 46

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

Question 47

Oncoviruses generally have what type of genome

Answer 47

DNA

Question 48

Proto-oncogenes

Answer 48

Encode protein that function in normal cellular growth and differentiation

Question 49

Inclusion Bodies

Answer 49

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

Question 50

Regulators of the cell cycle

Answer 50

Proto-oncogenes Tumor suppressor genes

Question 51

Tumor Associated Genes

Answer 51

Products of other mutated genes

Question 52

Apoptosis

Answer 52

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

Question 53

Neoplasm

Answer 53

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

Question 54

Metastasis

Answer 54

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

Question 55

Role of cytotoxic T lymphocytes in the extrinsic apoptotic pathway

Answer 55

* 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

Question 56

Intrinsic (Mitochondrial) Apoptotic Pathway

Answer 56

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

Question 57

Cytopathic Effects on host cells can be

Answer 57

Complete destruction of cells Subtotal destruction of cells Focal distruction of cells

Question 58

Cell transformation

Answer 58

changing of a normal cell into a cancer cell