Understanding Viral Evolution: Origins, Diversity, and Drivers, Slides of Human Resource Management

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Evolu&on

1

• Where did viruses come from?

• Where are they going?

• How are they geLng there?

• How would we know?

Today’s ques&ons

2

The public is constantly confronted with the

reality of viral evolu&on (even if they don’t

believe in evolu&on)

• New viral diseases: AIDS, West Nile virus in the US,

hepaNNs C, Ebola, Marburg...

• Regular bouts every year with influenza and common

cold viruses

• Drug resistant HIV

Simple fact: viruses evolve faster than many can comprehend 4

Viral evolu&on: The constant change of a viral

popula&on in the face of selec&on pressures

• If the populaNon can’t change or adapt, it disappears

• Viral populaNons display spectacular diversity -­‐ why

they are successful

• Sources of diversity:

-­‐ Muta-on

-­‐ Recombina-on

5

When it comes to viral evolu&on, the median is

not the message (Stephen Jay Gould)

• Viral populaNon diversity provides surprising avenues

for survival, yet every individual is a potenNal winner

• SomeNmes even the most rare genotype in a

populaNon may be the most common a]er a single selecNve event 7

Four main drivers of virus evolu&on

• Large numbers of progeny

• Large numbers of mutants

• Quasi-­‐species effects

• SelecNon

8

Replica&ng viruses produce large numbers of

mutant genomes

• EvoluNon is possible only when mutaNons occur in a

populaNon

• MutaNons are produced during copying of any nucleic

acid molecule 10