Virus evolution Flashcards
What is a way to make a limited number of proteins go further?
lysis proteins produced in frame shift
saves genetic material
do not produce lysis protein all the time
have genes in final and in other functional version - make gene go further
How can a bigger capsid be made?
more copies of the same capsid protein
increased T number
What is the mimivirus capsid composed of?
almost exclusively from hexamers
What is the structure of HBV capsids?
capsid is encapsidated by lipid envelope
some T=3, some T=4
What capsid does bacteriophage P2 form?
normally icosahedral T=7
presence of P4 - assembled into small T=4 capsid
How can viruses co-infect?
package genetic material in more than 1 capsid
division of genomes
What are the properties of capsid proteins?
highly positively charged rich in arginine & lysine package nucleic acid nucleic acid binding proteins self assemble
What is nucleation?
condensation of proteins around the genome
What are quasi species?
error-prone nature of RNA replication
All RNA viruses have quasi species
What is the catastrophe theory?
if quasi-species goes beyond mutation limit - population no longer viable
error catastrophe
How can HCV be treated?
Ribovirin
incorporation can be mutagenic
incorporates cytidine and uridine with equal efficiency in vitro
How can translation be sped up/slowed down in viruses?
mess up codon usage
can do this due to availability of acetylated tRNAs
What factor can indicate recent zoonosis?
The level of match in codon pair bias/dinucleotide frequency between virus and host
What is an example of ‘evolution in progress’?
Chikungunya - joint pain
viruses can now infect albopictus mosquitos of Southern Europe
How can evolution be used to make more stable virus particles?
stables particles = better vaccines
compensatory mutations in genome structure to make a better vaccine
