Virology: Chapter 4 Flashcards
(20 cards)
There are 4 outcomes to for cells infected with the virus, what are the 4 outcomes ?
Lytic/Acute, persistent, latent, oncogenic
Explain lytic / acute infection in the terms of
Virus:
Fate of cell:
Fate of person:
Example:
Virus: DNA / RNA (naked)
Fate of cell: lysis
Fate of person: if the cells are replaced then no permanent damage
Example: poliovirus, common cold
Explain persistent infection in the terms of
Virus:
Fate of cell:
Fate of person:
Example:
Virus: DNA/RNA (enveloped)
Fate of cell: virus progeny buds out SLOWLY, cell stays alive for week/months
Fate of person: sick for weeks bcs virus evades immune system (envelope) and cause inflammation
Example: Measles, rubella
Explain latent infection in the terms of
Virus:
Fate of cell:
Fate of person:
Example:
Virus: DNA / Retrovirus (integrate, and hide for years)
both naked & enveloped
Fate of cell: virus inactive, no expression (will wake up later)
Fate of person: depends on virus
Example: HIV, Herpes zoster, Herpes simplex, Epstein Barr virus (Burkitt’s Leukimia), HTVL-1, HTVL-2 (Leukimia)
Explain oncogenic infection in the terms of
Virus:
Fate of cell:
Fate of person:
Example:
Virus: DNA / Retrovirus (integrate and actively express)
both naked/enveloped
Fate of cell: disrupt cell growth == uncontrollable == tumor == cancer
Fate of person: cancer
Example: HPV, Hepatitis B
Viruses don’t always have to kill the cell to be successful because many of them have evolved to co-exist, so cells can respond to infection in 3 other ways:
- No apparent change
- Cytopathic effect
- Loss of Growth Control (Tumor)
No apparent change
Virus is present, but cell looks normal
Latent infections
Cytopathic effect
signs shown when a virus infects
what are the signs of cytopathic effect (3)
They go through morphological changes
- inclusion bodies: clumps of protein
- fusion of cells: synctium (fuse tgt form big cell)
- cell death
Loss of growth (transformation)
when the infected cell loses control over its division and grow uncontrollably causing tumor and cancer (neoplasmic transformation)
What is pathogenicity
capacity of the virus to cause damage to host cell and it’s functions
How do viruses cause disease? What causes the damage? (2 things)
the virus itself and the immune system (by releasing cytokines after detecting a virus === inflammation)
What determines where a virus replicates?
A virus can only infect certain tissues / organs depending on (3 things)
- virus attachment proteins (antireceptor)
- receptor
- intracellular factors used for replication
Viruses are assembled from 2 individual components:
proteins and nucleic acids
Why is cultivation needed?
Viruses need living cells to replicate and they have to be permissive and susceptible
What are the 3 ways you can cultivate
in vivo (through animals)
in vitro (primary and continuous culture)
in ovo (in egg)
Which method is good for mass vaccine production
embyronated egg (in ovo) and continuous culture
which cell type (eukaryote / prokaryote) need growth factors
eukaryote
What is the difference between primary and continous cell culture
primary:
- divide a limited amount of time until they have contact inhibition (touching), creating a monolayer
continuous
- divide unlimited times, no contact inhibition
Why is continous culture (transformed cell line) a convenient way to cultivate virus
because transformed cell lines are derived from single cells, ensuring uniform growth and genetic composition, and susceptibility to infection
