Trevor Bedford and his lab -- terrific collaboration since 2014

especially James Hadfield, Emma Hodcroft, Ivan Aksamentov, Moira Zuber, and Tom Sibley

Data we analyze are contributed by scientists from all over the world

Data are shared and curated by GISAID

• SARS-CoV-2 is in the same family as SARS-CoV-1, MERS and
  two seasonal coronavirus
• The latter cause mild disease, the former severe
• Relatives are found in many different animals
• Closest known relative of SARS-CoV-2 is a virus isolated from bats
  (RaTG13, approx 96% identical)
• SARS-CoV-2 spreads more easily than SARS-CoV-1 or MERS;
  pre-symptomatic transmission makes it hard to control

• 29k linear (+)ssRNA genome -- one of largest RNA virus genomes
• the first 2/3 code for the replication machinery
• While it spreads, it accumulates about 2 mutations per month

Early genomes differed by only a few mutations, suggesting very recent emergence

• The outbreak originated from one source
  → not repeated zoonoses from a diverse reservoir.
• The common ancestor of all samples was Nov - early Dec 2019.
• Family clusters showed up as identical genomes (expected)
• A second clade emerged that will continue to spread

Trevor Bedford and his lab -- terrific collaboration since 2014

especially James Hadfield, Emma Hodcroft, Ivan Aksamentov, Moira Zuber, and Tom Sibley

Data we analyze are contributed by scientists from all over the world

Data are shared and curated by GISAID

WRONG:

Low genetic diversity combined with very biased sampling → no directionality can be inferred