Viruses Part C Flashcards
Exam 2
What is the mechanism of adsorption and penetration for a eukaryotic virus?
- Fusion with the plasma membrane (since there is no cell wall)
- Entry started, but nucleic acids still within the capsid that need to be released - Endocytosis (receptor mediated)
- Virus gets coated by coated pit, endosome created, capsid gets removed to expose the nucleic acids
How are animal viruses released?
- Lysis
- Budding (may not kill the cell)
- Nucleocapsid pushes out of the host membrane, wraps itself in host membrane to give envelope (commonly uses Golgi apparatus or E.R.)
Replication of dsDNA virus (Herpes simplex virus I, or HSV I)
Rolling circle replication mechanism
- (+) strand is copied to make complimentary strand (-)
- Strand that is made will be template for the other complimentary strand (+)
What kind of infections can Herpes simplex virus I, or HSV I create?
All types
- Acute infections (depleting cell resources, virus makes many copies and kills host cell)
- Persistant infections
- Latent infection (virus goes dormant, can be reactivated)
- Chronic infection (slow rate of replication of virus, may not have signs of disease or kills host cell)
- Transformation into malignant cell (mutating and causing cancer)
What form of (m)RNA can be translated into a protein?
(+) (m)RNA
Which Baltimore group of Eukaryotic viruses can immediately be translated in the ribosome?
(+) stranded RNA virus
What symptoms/effects does rotavirus cause and how is it transmitted?
Diarrhea
- Highly infectious, spread oral-fecal route. Attacks intestine cell (enterovirus)
- Creates viroplasm (a “cytoplasm” that would not be present in a non-infected cell)
What symptoms/effects does poliovirus cause and how is it transmitted?
Neuromuscular system effected, can affect diaphragm (can’t constrict and contract, causing suffocation)
-Infected by consumption of infected water/swallowing virus
What is proteolysis?
“Chopping up” a polyprotein (created by translation) into viral proteins
What are the 3 types of influenza?
- Influenza A
- Seasonal epidemics (mild –> severe)
- Infects many animals
- Subtypes, which can be broken down into strains
- Influenza B
- Seasonal epidemics (mild –> severe)
- Infects only humans
- No subtypes, but has strains
- Influenza C
- No pandemics (Causes only mild respiratory illnesses, like a cold)
What is antigenic drift? (involved in making new influenza viruses)
Small changes that involve mutations in the spikes within influenza A or B
- Causes different strains
- Accumulated changes results in new strains every 2-3 years
- Accounts for local increases in cases
What is antigenic shift? (involved in making new influenza viruses)
Large, abrupt changes in genome (only in influenza A) that occur occasionally (SARS CoV2)
- Sudden appearance= little immunity (no prior exposure to new type of virus
- Occurs when reassortment of genomes when same host is infected by 2 or more different flu strains (virus from animal population and human population)
- Causes new subtypes/virus to occur
- Results in new spike proteins
What characteristics are important for influenza virus?
Has two types of spikes: -Hemagglutinin (adsorption) -Neurominadase (release) Genome is segmented -Has 8 -mRNA subunits making up its genome
What can be done to avoid the transmission of influenza?
- Good hygiene (washing hands)
- Vaccines
- New one each year because there could be new strains/subtypes
- Vaccines stimulate antibodies against the viral spikes
What is the direct test for SARS CoV2?
Looks for presence of virus by:
-Detecting viral RNA in the bodily fluids/cells
OR
-Detection of viral antigens (proteins) in the bodily fluids using antibodies (done on campus)
