Lecture 27 - Viral Evolution Flashcards
What are the 3 main hypothesis explaining origin of viruses?
virus-first | progressive of escape | regressive/reduction
What is the “Virus-first” hypothesis?
@ beginning of life = no cellular forms exist, ONLY RNA molecules with enzymatic activities capable of self-replication
What is the “progressive of escape” hypothesis?
viruses derived from cellular RNA/DNA fragments
What is the “regressive/reduction” hypothesis?
viruses come from primordial cells that lost their cellular elements during evolultion
What 2 events results in viral evolution?
mutation and selection
What are the 4 drivers of virus evolution?
large number progeny | selection | quasispecies | large number mutants (mutant genomes)
Which evolves faster, RNA or DNA viruses? Why?
RNA viruses because RdRp lacks proofreading ability
What does “quasispecies” mean?
no standard copy of genome; a population = genomes similar but not identical
What are the 5 new viral diseases?
Zika | Ebola | Sars | West-Nile Virus | Marburg
What 2 viruses humans regularly encounter annually?
influenza | common cold
What is the most known drug-resistant virus?
HIV
What is the “survival of the fittest”?
rare genome w/ particular mutation may survive a selection event | mutation found in progeny genomes
What is the “survival of the survivors”?
linked, unselected mutations get a free ride b/c of other mutations
What is antigenic drift?
mutations in proteins that antibodies don’t recognize
What is antigenic shift?
recombination of genomes (ie: from bird to human = shifted)
