Glossary of Medical Virology intro
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- What are 5 characteristics of viruses?
- 1. Can'tsee w/ lite microscope
2. Have to use EM
3. Obligately intracellular
4. Have RNA/DNA, not both
5. Don't respond to antibiots
- What is the smallest/largest virus?
- Smallest = Polio
Largest = Pox
- What are 4 characteristics of viral structure?
- 1. Nucleocapsid
2. Virion vs. viroid
3. Naked vs. Enveloped
- What is the nucleocapsid?
- the nucleic acid and capsid
- What is a virion?
What is a viroid?
- Virion = virus w/ complete capsid and nucleic acid.
Viroid = incomplete, doesn't have a capsid.
- What is an Envelope?
How does it form?
- extra outer layer - a capsule.
-Formed by picking up some membrane during budding of virus from host cell.
- What are the 2 types of symmetry?
- 1. Icosahedral (cubic)
2. Helical (coiled)
- What are the 6 steps in Viral replication?
- 1. Adsorption
3. Uncoating (eclipsing)
4. Nucleic acid replic/protein coat synthesis.
- What occurs in adsorption?
- Ads: viruses binds to host cells w/ the receptor for it.
Pen: by phagocytosis or melding
- What occurs in Uncoating?
- Eclipsing - the cell's enzymes release the nucleic acid from the capsule.
- What occurs in the course of viral nucl. acid replication and protein synthesis?
- the viral nucleic acid is replicated using the host's machinery, and new capsomeres are synthesized (protein) to make the capsid.
- What is interesting about the assembly process of viruses?
- It is the least efficient step in the whole replication process.
- What happens if viral assembly is incomplete?
- Pieces get left in the host cell and can be seen on a tissue biopsy as INCLUSION BODIES.
- Where does a DNA or RNA virus assemble?
- DNA = in the host's nucleus
RNA = in the host's cytoplasm.
- How is the virus released after assembly and all?
- It depends on the type of virus - whether enveloped or not.
- How does each release:
- -Env released by budding
-Naked released by lysis.
- What are the 5 steps in viral infection of host cells?
- 1. Transmission
2. Port of entry
3. Binding to specific receptor
4. Active infection
5. Latent infection
- What type of viruses especially cause latent infections?
- DNA viruses - like the herpes virus w/ cold sores.
- what is a latent viral infection in bacteria called?
- How does lysogeny affect C. diphtheriae?
- The virus encodes the exotoxin produced by the bacteria, and is released upon lysis.
- What are 3 host defenses to viruses?
- 1. Humoral
- How does each defense work -Humoral
- Humoral Prevents infection
Cellular helps recover
Interferon is species spcf and prevents a runaway infection.
- How does interferon prevent spread of infection?
- It is released from infected cells and protects neighbors.
- What are 7 methods for identifying viruses?
- 1. Tissue cultures (CPE)
2. Shell vial assays
3. Animal/chick embryo inoculat.
4. Cytological exam of host tissue
5. Immunological tests
6. Serological tests
7. molecular methods
- What is CPE?
- Cytopathic effect
- What are 6 effects viruses can have on host cells?
- 1. None
2. Inclusion bodies
3. Giant cells
4. Cell death
6. Chromosomal changes
- What does the location of an inclusion body tell about the virus?
- -If in nucleus of cells, its a DNA virus
-If in cytoplasm, an RNA virus.
- How do viruses cause giant cells?
- by causing nuclear divisions without cytoplasmic.
- What's an example of prolif caused by a virus?
- How do you do a tissue culture?
- -Put down a monolayer of cells.
-If tube, use roller drum to keep virus on all cells.
-Look for CPE
- What is a shell vial assay, how is it done?
- 1. monolayer of cells on coverslip
2. add specimen; centrifuge at 35 for 30-45 minutes
3. Incubate for 24 hrs
4. Flood with Ab-flour
5. Incubate, wash, UV scope
- What information is being sought when identifying viruses?
- -Time takes for growth
-Cytopathic effect it has
-Type of cell line it grows on
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