Viruses Flashcards
What is the genetic material of a virus
called its genome and can be made up of RNA or DNA
what is a naked vs envaloped virus
Enveloped viruses typically have glycoproteins that protrode from the envelope important for attachment + entry
what structure protects the genome in a virus and what is it made of
Capsied which is made of capsomeres
can be helical, polyhedral, bullet or spherical
What is the nucleocapsid
Combo of capsid and genome together
What is a + sense virus and - sense virus
Positive- can use their genomes to make proteins as soon as they are in host cytosol (mRNA)
Negative- RNA must first be converted to + sense by RNA dependent RNA polymerase before it can be translated
What is a class 1 virus and ex
Ds DNA virus
herpes
What is a class 2 virus and ex
ssDNA viruses
parvovirus
What is a virus called that integrates itself into human genome
Provirus (usually DNA viruses can do this)
What is a class 3 virus and ex
ds RNA virus
rotavirus
What is a class 4 and 5 virus and exs
4- ss RNA (+)- hep a
5- ssRNA (-)- influenza, ebola
What is a class 6 virus and what can they do
(+) ss RNA virus with reverse transcription step
The RNA can be converted to DNA then be inserted in the host dna
What is a class 7 virus and what can they do
DNA virus with reverse transcription step
(hep b)
can integrate into human genome
Hwo does a virus attach
Viral ligands bind to attachment receptors on target cell
What are the 2 ways a virus can enter
Fusion- enveloped viruses can fuse w host cell plasma membrane
Receptor mediated endocytosis- Viral pro goes in via a endosome and then can fuse with the endosome membrane
What is uncoating of a virus
Process where viral capsid pro deteriorate so viral genome can be released
How does DNA and RNA viruses replicate in the host cell
DNA- in hosts cell nucleus
RNA- in cytosol
both use hosts nuclear import machinary
How do viruses egress (leave)
via budding (uses host cell membrane), cell lysis (kills cell) or exocytosis (energy dependent)
What are cytopathic effects
The damaged incurred by infection by virus
ex. holes in monolayer, rounding of infected cells etc
lytic cycle of bacteriophage
Phage infects cell
virus dna multiplys and new phage particles made
Cell lyses releasing phages
Lysogenic cycle of bacteriophage
phage infects cell
phage dna icorporates into host dna
as cell divides the phage dna is passed to offspring
(can move into lytic cycle after)
What is susceptibility, permissivity and tropism
Susceptibility- refers to whether a virus can bind to a cellular receptor and enter cell
Permissivity- refers to ability to replicate in a cell
Tropism- range of cells susceptibe to infection
