Influenza

Influenza virion

Influenza life cycle

1918 "Spanish flu"

Flu pandemics caused by host switch events

Host switch events often occur through reassortment

Host switch events often occur through reassortment

Reassortment creates different histories

Influenza B does not have pandemic potential

Phylogenetic trees of different influenza lineages

Seasonal influenza evolution

Influenza H3N2 vaccine updates

H3N2 phylogeny showing antigenic drift

H3N2 phylogeny showing antigenic drift

Influenza hemagglutination inhibition (HI) assay

HI measures cross-reactivity across viruses

Data in the form of table of maximum inhibitory titers

Compiled HI data difficult to work with

Antigenic cartography positions viruses and sera to recapitulate titer values

 

Antigenic cartography positions viruses and sera to recapitulate titer values

 

Combine phylogeny and HI data to estimate a joint antigenic map

Drift results from selective advantage of antigenically novel lineages

Seasonal influenza geographic circulation

Seasonality in influenza

Sample H3N2 from around the world

Treating geographic state as an evolving character

Phylogeny of H3 with geographic history

Infer geographic transition matrix

Air travel predicts migration rates

Geographic location of phylogeny trunk

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