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49 Cards in this Set
- Front
- Back
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What is a capsid?
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A symmetric protein shell that encloses a virus' nucleic acid.
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What are the 2 functions of a capsid?
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1. To protect the nucleic acid.
2. To aid in infection of host cells |
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what is the name of a
capsid + enclosed nucleic acid? |
Nucleocapsid
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How is a Nucleocapsid different from a virion?
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A virion can be simply a nucleocapsid, or that with an envelope as well. The complete infective virus particle.
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Give 3 examples of viruses that have a virion = nucleocapsid:
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1. Adenovirus
2. Papovavirus 3. Picornavirus |
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Give 2 examples of viruses that have an envelope in addition to the nucleocapsid:
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1. Herpesvirus
2. Myxovirus |
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What is a CAPSOMERE?
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A cluster of polypeptides which form a capsid on isometric virus particles.
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How are capsomeres visible?
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With electron microscopy; they are morphologic units.
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What are Structural units of a virus?
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The basic building blocks of the capsid - may be individual polypeptides.
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So how do structural units and capsomeres differ?
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Capsomeres are clusters of polypeptides, where struct. units are individual pp's.
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What is a PSEUDOVIRION?
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A particle that looks like an ordinary virus, but actually contains the wrong nucleic acid - that of the host cell.
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How do pseudovirions function compared to normal viruses?
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They cannot replicate.
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What is PRIMARY nucleic acid structure?
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the base sequence in the acid chain.
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What is SECONDARY nucleic acid structure?
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the spatial arrangement of the complete chain - tells whether it is ss or ds.
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What is the TERTIARY strcture?
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Fine spatial detail; supercoils, deletions, gaps, cations, etc.
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What is Transcription?
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Transfer of Nucleic acid information to mRNA.
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What is Translation?
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Using the mRNA to build a specific amino acid sequence and protein!
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When you picture a virus, what do you see?
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---Nucleic Acid Center---
---Capsomeres together making up the Capsid Coat--- Envelope Surrounding the Nucleocapsid. |
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What is an envelope made out of?
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Lipid material from the host cell's membrane.
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What enzymes are contained in viruses along with the genome?
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Replicative enzymes --> NOT oxidative enzymes; that's what the host cell is for!
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What acronym stands for the 6 steps in viral infection?
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APURAR
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What does APURAR stand for?
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A = Attachment
P = Penetration U = Uncoating R = Replication/Reproduction A = Assembly R = Release |
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How do viruses attach to host cells?
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With specificity, like an Ag-Ab reaction.
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What are 5 cellular responses to a viral infection?
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1. Cell injury
2. Proliferation 3. Inclusion production 4. No visible change 5. Giant cell formation |
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What is the acronym for cell response to infection?
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CPING... like shhh the cell is sleeping
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-What are some indicators of cell injury?
-What is another name for this? |
Ballooning, vacuolization, death.
Cytopathic effect, CPE. |
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What are the 4 main contributors to CPE?
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1. Cellular metabolism diversion
2. Lysozomal damage 3. Cell membrane damage 4. Toxic viral products |
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Why is diverting cell metblsm so cytopathic?
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Intended to keep Na/K pumps working to keep K inside the cell and Na out; if this fails, the cell breaks down.
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How does the cell membrane contribute to CPE?
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During penetration the virus leaves antigenic fragments which cause immunological damage later.
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What is the most common type of cell proliferation, and what virus is associated with it?
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Liver cell carcinoma.
Chronic Hepatitis C. |
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What are 4 main contributors to viral pathogenicity?
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1. Portal of Entry
2. Local replication/spread 3. Dissemination 4. Shedding sites |
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What are common portals of entry for viruses?
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Oral, anal, respiratory, venereal.
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What is viral TROPISM? What is a major determinant in this?
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-Viral affinity for specific body tissues.
-Important factor is presence of receptor for specificity. |
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What are 2 alternate ways of viral dissemination?
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1. Viremic
2. Neural |
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What is Viremic spread of infection?
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Via the lymphatics, to enter the circulatory system. Virus may infect white cells as vehicle.
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What is neural spread? What virus exhibits it?
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Via the neurons/ganglia; Rabies.
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What symptoms are seen in the incubation period of infection?
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None - its usually asymptomatic.
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List 4 ways to RESIST viruses:
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1. Lack the receptor
2. Develop Antibodies 3. T-Cells 4. Interferon |
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What two specific ways do antibodies neutralize viruses?
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1. By binding virus receptors, Ab blocks it from binding target host cells!
2. By binding virus, the complex can activate ADCC or complement-mediated lysis. |
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What antibody classes participate in viral defense?
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IgM, IgG, and IgA.
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What role does cell-mediated immunity play in fighting viral infections?
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T cells are very important, as well as cytokines.
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Which leukocytes can recognize and kill infected host cells?
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T-cytotoxic cells
NK cells Macrophages |
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Which leukocytes produce antiviral cytokines?
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T-helper cells
NK cells Monocytes |
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What is the main purpose of the nonspecific immune response to viruses?
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To prevent proliferation and replication of the disease.
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What is the main player in this nonspecific response?
When are they seen at work? |
-Interferon and NK cells.
-Seen early in the acute phase. |
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What is the main purpose of the specific immune response?
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-To eliminate virus at the END of the acute phase, and develop specificity to prevent future infections.
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HOw are antibodies and interferon SIMILAR?
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Both are made of protein.
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What are Ab and INF each specific FOR?
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Antibody: virus
Interferon: host |
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What are the 6 stages of Illness in viral infections?
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1. Incubation
2. Prodrome 3. Onset 4. Acute Phase 5. Recovery 6. Convalescent |
