Effects of Viruses on Host Cell Flashcards
What are 3 effects of viruses on host cells?
- Cytocidal
- Non-cytocidal
- Cell transformation
Cytocidal effects on host cells lead to cell death via ____________ or _____________
- Lysis
2. Apoptosis
Non-cytocidal effects of viruses on host cell lead to what kind of infections?
Persistent infections
Cell transformation effects of viruses on host cells lead to __________ cells
Tumor
What is a cytopathic or cytopathogenic effect?
Damaged or morphological changes to host cells during virus invasion
Cell fusion involves the fusion of _____________ membrane of 4 or more cells to produce enlarged cell with 4 or more nuclei
Plasma
Cell fusion results from fusion of an ______________ cell w/neighboring _______________ or _______________ cells
- Infected
- Infected
- Uninfected
T/F: Inclusion bodies in host cell during viral replication help ID certain viral infections
TRUE
Inclusion bodies are abnormal structures in cell __________ or ____________ or both, having characteristic staining properties
- Nucleus
2. Cytoplasm
Inclusion bodies can be what 3 things?
- Accumulation of viral components
- Result from degenerative charges in cell
- Crystalline aggregates of virions
Acidophilic staining recognizes for ______ dyes and appear the color _________
- Acid
2. Pink
Baso Philip staining recognizes ________ dyes and appears a ______/_______ color
- Basic
2. Purple/blue
What are 5 types of mechanisms of virus-induced cell injury and death?
- Inhibition of host-cell nucleic acid synthesis
- Inhibition of host-cell RNA transcription
- Inhibition of host-cell protein synthesis
- Lysosomes release hydrolytic enzymes, which destroys cell
- Interfere with cell membrane function
Apoptosis is ___________ cell death
Programmed
What mediates cell death?
Activation of host-cell caspase enzymes
_____________ are responsible for degradation of cell’s own DNA and proteins
Caspases
What is the intrinsic (mitochondrial) pathway?
Activated as result of increased permeability of mitochondrial membrane subsequent to cell injury
How is the extrinsic (death receptor) pathway activated?
Activated by engagement of specific cell-membrane receptors, which are members of TNF receptor family
Cytotoxic T lymphocytes and NK cells can initiate apoptosis, using preformed mediators such as ___________ and ____________ that directly activate caspases in target cell
- Perforin
2. Granzyme
Antibody-dependent cell mediated cytotoxicity results from what?
Surface membrane fusion of enveloped viruses
What is cell transformation?
Change of normal cell to cancer cell
What is neoplasia?
Abnormal tissue overgrowth that may be localized or disseminated
What is a benign neoplasm?
Growth produced by abnormal cell proliferation that remains localized and does not invade adjacent tissue
What is a malignant neoplasm?
Locally invasive and may also spread to other parts of body
What is metastasis?
Spread of cancer cells from the part of the body where it started to other parts of body
What are two important tumor suppressor genes?
Rb and p53
What are tumor suppressing genes?
Plays role in keeping cell division in check and encodes proteins that regulate and inhibit uncontrolled growth
What are proto-oncogenes?
Encode proteins that function in normal cellular growth an differentiation
What are oncogenes?
Mutated forms of proto-oncogenes or aberrantly expressed proto-oncogenes
What is Rb: retinoblastoma protein?
Important tumor suppression gene/protein that blocks E2F and keeps cell division in check
What is p53 protiein?
Important tumor suppression gene/protein that prevents cells w/damaged DNA from entering cell division; if no repair can happen, mediated apoptosis
Oncogenic viruses generally have a _________ genome
DNA
What are oncogenic DNA viruses?
Have viral oncogenes in viral DNA
What happens when oncogenic DNA viruses infect permissive cells?
They can replicate successfully and results in no cancer/cell lysis
What happens when oncogenic DNA viruses infect non-permissive cells?
Cannot replicate and results in cancer or replication
What are acutely transforming retroviruses?
Steal proto-oncogene from infected host cell DNA and the virus converts the proto-oncogene into oncogene (cancer causing gene)
What is a slow/chronic transforming retrovirus?
Virus genome gets inserted into regulatory gene of host cell DNA and regulatory cannot function properly , resulting in excessive cell division or cancer
What are tumor antigens?
New antigens appear on surface of tumor cells that may provoke immune response
How are tumor antigens expressed?
FOCMA
