test 3 Flashcards
(103 cards)
What were the first 2 viral diseases to be investigated, and by who?
rabies by Pasteur;
yellow fever by Walter Reed.
What are viruses and how can they be grown?
Viruses are non-living intracellular parasites that cannot be cultivated in cell-free media. Must be grown in tissue culture, frequently grown in embryonated bird eggs
What is the largest virus?
Poxviruses - 200 nm.
What is a single virus particle called?
Virion.
What is virus genome like?
Either RNA or DNA not both.
Where is the nucleic acid of a virus found at?
enclosed in protein coat called a capsid
nucleic acid + capsid = ?
nucleocapsid
Some viruses have Lipoprotein envelops acquired from where?
Host cell.
Virus envelopes have what for interaction with host cell?
Glycoprotein spikes.
What is a naked virus?
A virus with a capsid but no envelope.
What are the shapes of viruses?
including spherical, bullet shaped, or filamentous
What are the shapes of capsids?
Two primary types of symmetry of capsid 1. helical or 2. icosahedral
What is an agent with no detectable Nucleic acid?
Prion.
What is a prion?
A self replicating protein.
Prions are related to what?
Some scientists believe a relationship to viruses exists
What are prions responsible for?
Responsible for the neurodegenerative diseases classified as spongiform encephalopathies (SE).
Prion diseases cause what?
Diseases cause holes in tissue, brain appears as a sponge
Spongiform encephalopathies caused by prions include what 4 diseases?
SEs include mad-cow disease, Creutzfeldt-Jacob, Kuru, scrapie
How did we learn about virus replication?
Much of our understanding comes from studying bacteriophages (bacterial viruses)
What are the 5 stages of bacterial viral infection (reproduction)?
- Adsorption. 2. Penetration. 3. Prefabrication. 4. Maturation. 5. Viral release.
What is adsorption?
bacteriophage irreversibly adsorbs(stick to the side) to receptor site using tail fibers
What are the different receptor sites for adsorption?
Lipopolysaccharide of Gram neg. cells, pili, & flagella.
What period begins after adsorption and how long will it last?
Beginning of latent period- latent period continues until cell lyses
What is the 2nd step (penetration) like?
phage tail penetrates bacterial cell, nucleic acid enters leaving capsid on outside of host cell.