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SUMMARY:Selection in human viruses: From HIV to SARS-CoV-2 (and what the f
 uture might hold) - Dr Katrina Lythgoe\, BDI\, University of Oxford
DTSTART:20210707T150000Z
DTEND:20210707T160000Z
UID:TALK161350@talks.cam.ac.uk
CONTACT:Dr Ciara Dangerfield
DESCRIPTION:Viruses replicate and evolve within the hosts that they infect
 \, but sooner or later they need to transmit if they are going to survive 
 in the long term. This creates an evolutionary trade-off\, because what ma
 kes a virus fit within a given individual does not necessarily make it goo
 d at transmitting. We might expect this tension to be strongest for chroni
 c viral infections\, like HIV\, which can undergo years of rapid within-ho
 st evolution between transmission events. But for acute viruses\, like SAR
 S-CoV-2\, these tensions are expected to be weak as the virus rapidly jump
 s from individual to individual\, with little opportunity for within-host 
 selection. This is supported out by ours’ and others’ findings that wh
 en viral loads are high and transmission is most likely\, SARS-CoV-2 has l
 ittle genetic diversity and a narrow transmission bottleneck. How then doe
 s the appearance and success of new variants of concern\, which apparently
  emerged within chronically infected individuals\, fit into this framework
 ? I argue that by changing the properties of the host population\, for exa
 mple as a consequence of host shifts or mass vaccination\, we are fundamen
 tally changing the nature of the trade-off between selection at the within
 - and between-host levels. I will finish with a brief discussion on what t
 his might mean for modelling SARS-CoV-2 viral dynamics in the context of v
 iral evolution in the future.
LOCATION:Zoom
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