Exam 2 Lecture 17 Flashcards
(22 cards)
Baltimore Classification System Group I
dsDNA either uses it’s own or the host DNA polymerase
Herpes
Baltimore Classification System Group II?
ssDNA- needs to go through dsDNA intermediate to replicate the plus strand
Parvovirus in Euks
Phages- M13 or øX174
Baltimore Classification System Group III?
dsRNA- Needs RNA dependant RNA polymerase to make mRNA and genomic RNA
Always RNA, never DNA!
Rotavirus
Baltimore Classification System Group IV?
(+) ssRNA- the RNA can act as mRNA, needs RNA polymerase to make template stand for more mRNA or replication
Always RNA, never DNA!
Coronavirus, Polio, Hep C
Phage- MS2
Baltimore Classification System Group V?
(-) ssRNA - Needs to be RNA polymerase to replicate and has to be transcribed to a complement strand/mRNA
Always RNA, never DNA!
Influenza, Measles, Rabies
Baltimore Classification System Group VI?
Retrovirus, (+) RNA has its own reverse transcriptase to make dsDNA intermediate
HIV
Baltimore Classification System Group VII?
dsDNA- pararetrovirus, requires host reverse transcriptase to make dsDNA
Hep B
Plus strand DNA compared to mRNA code?
The same, mRNA always matches plus-strand!
(-) strand DNA compared to mRNA?
Acts a template for mRNA
(-) strand RNA?
Needs to be transcribed to make mRNA
How easy is it to map viral evolution?
Why?
Difficult- there is not one conserved gene such as ribosomes to map it from.
They regularly exchange genomic data with hosts, tend to be mosiac
Are mapped using protein similarities sometimes
Describe MS2 phage?
linear (+) ssRNA in an icosahedral capsid
binds to F pilus of E coli
Lytic phage ~25 mins to release 100s-1000s of progeny
MS2 replication strategies?
+ strand used to make minus-strand with RNA replicase
+ strand translated to make viral capsid proteins and RNA replicate
(-) strand replicated with RNA replicase to make plus-strand
Self-assembly then lysis protein made and host is lysed releasing virions released
Is there proofreading activity during MS2 replication?
No, so the mutation rate is high
Do all MS2 genes replicate at the same time?
No, they exhibit temporal regulation. Ribosome binding site for capsid protein always available, once that is translated it opens up replicase gene binding site
Where on F pilus do phages bind?
Icosohedral MS2 binds to side
M13 filamentous binds to tip of pilus
Describe the M13 phage?
ssDNA 6400 base circular strand wound/encased in a long filament capsid w/ 90% coding sequences, No envelope
Asymmetric with distinct proteins at each end.
Some of the genes overlap
M13 replication strategy?
- ssDNA (+) uses host replicase to make dsDNA
- The dsDNA neg strand uses host cell’s RNA polymerase to make more viral genomes and mRNA to make capsid proteins
- Phages self assemble and exit host by budding
Notes- Host divides ore slowly while infected but can still divide and pass M13 on to each daughter cell, this is a common way to reproduce for filamentous phages
What is the M13 assembly and export apparatus related to?
A Type II secretion system
Uses Proton Motive Force to secrete but still maintains PMF and cellular metabolism function
dsDNA phage basic characteristics?
Large more complex genomes, heads and tails, defined order of gene expression, many are lytic but some interact differently
Descride a T4 phage?
Linear dsDNA, 169 kb encoding 300 genes
Relies on E coli host core RNA poly for first transcription and translation
Binds to lipopolysaccharide and OmpC Porin
Clear temporal replication, DNA first and capsid proteins later
Related viruses to T4?
T even phages, T2 and T6, closely related but have different binding sites
