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33 Cards in this Set
- Front
- Back
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What are main criteria for classification of virus
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type of NA - RNA or DNA
Number of strands of NA & construction(single or double stranded, linear, circular, with/w/o breaks, segmented or non) symmetry of nucleocapsid polarity of the genome(+ or -) Presence or absence of lipid envelope |
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What is a virus
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infectious, sub-cellular, obligate intra-cellular parasite
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What is another word for Virus particle?
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Virion
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Compare particle size to other cells
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Virus 3-380 kb (<200 genes)
Bacteria ~2000 kb (4K genes) Human ~ 2 x 10 6th(60K genes) |
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What is composition of Viruses under heading GENOME
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Haploid (xcept retrovirus)
DNA or RNA a. RNA may be + or - sense Non-segmented or segmented(bisegmented does not mean diploid) Single or double-stranded a. all DNA are dbl X parvo b. All RNA x retro are single |
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Which type of strand is infectious
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negative
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What is the nucleocapsid
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Protein coat
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What is the purpose/structure of nucleocapsid
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1. Protects, binds
2. Usually regular, repeating structures based on sub-units (1-30 diff proteins) 3. morphology |
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Describe morphology of nucleocapsid (Helical first)
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Helical
1. relatively few diff proteins 2. Genome size not fixed 3. Form of most RNA viruses 4. ALWAYS has lipid envelope |
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Describe Icosahedral morphology
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more complicated, usually ass w DNA viruses
1. 20 sided ball of triangular surfaces 2. Greater diversity of proteins 3. size frozen 4. form of all DNA x poxivirus 5. May/may not have lipid env |
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Third type of Capsule is Complex. What does this mean
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more complicated architecture of few very large viruses, such as poxvirus
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What is scaffold proteins
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?
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What happens with negative stranded RNA viruses (regarding nucleocapsid
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remains packaged with genome
ass with the RNA polymerase |
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Talk about the Virus Envelope formation
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1. Lipids derived fro budding through cell membranes
2. Embedded glycoprotein 3. Advantages and disadv relative to non-env viruses |
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Lipids derived from budding through what cell membranes?
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1. External cell membrane
2. endoplasmic reticulum 3. nuclear membrane 4. other internal membranes |
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Describe Embedded glycoprotein and their impact on virus
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may cause irregularity in shape. 1st thing the immune system sees and responds to.
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What are advantages and disadv relative to non-enveloped viruses
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1. less constrained because surf proteins not all dedicated to protecting virus
2. evolve more easily in response to immune pressure 3. sens to detergents (also sens to heat, light) Not very hard in envirnment, easily disrupted. need person to person transmission for viability. |
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Discuss glycoproteins of viruses
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1. embedded in lipid envelope
2. encoded by virus 3. folded in endoplasmic reticulum & delivered to cell membrane via golgi apparatus 4. Attachment domains 5. Immune system targets |
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Discuss Glycoproteins in endoplasmic retic - what assists process
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chaperonins - proteins that assist in folding to make tertiary structure
2. attached carbohydrate helps solubility |
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Discuss attachment domains of glycoproteins
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Hemagglutinins (bind RBCs)
Fusion proteins Enzymatic activity(i.e. neuraminidase) |
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What functions as immune system targets in virus
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glycoproteins
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What viruses are used as vectors for vaccines
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Adenoviruse and Venzualan equine enceph (VEE)
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Describe polymerases and their role in viral replication
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They are the enzyme that will replicate the strand.
1. RNA dep RNA polymerase(viral encoded) 2. DNA polymerase(virus or cell encoded) Adv in humans as we have DNA polymerases |
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How well does the arbovirus survive with lipid envelope?
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well as it is alway in arthropod
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Is fecal-oral a possible transmission for lipid envelope viruses
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probably not as out in envirrnment too long to survive elements.
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RNA dependent RNA polymerases are harder or easier to come by in humans?
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harder as humans don't make RNA polymerase.
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What are matrix and tegument proteins of virus
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?
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Describe proteins that interfere with host defenses
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secreted glycoprotein of Ebola virus
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Describe pseudotypes of glycoproteins
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Used for research - (YF vaccine) - create a pseudotype with glcoprotein on surface sim to v. virulent virus to test (can get away without using level 4 lab, etc)
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How do virus assemble themselves
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MYSTERY!!
1. self assembly 2. budding |
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what proteins are used in pseudotypes?
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foreeign proteins substituting for normal GlycoP
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What is Maturation cleavage and when does it occur
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often required to activate infectivity - may be pre or post-release form cell
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What is neutralization of charge?
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inclusion of polymers/proteins to counter negative charge of nucleotides
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