We performed a timeline analysis using the sample collection dates reported in the
GISAID EpiFluTM database, and found that individuals infected with SARS-CoV-2
strain containing the Group 4 ORF3a mutant had reached the West Coast of the
United States (Orange County, California) by January 22, 2020 at the latest.
Immediately afterwards, and preceding or at nearly the same time as first Group 4
cases in Sichuan, additional isolates (Figure B) of this strain were reported in China
(Taiwan), France (Paris), and Australia (Sydney and Clayton). According to the
official records, these individuals either traveled from Wuhan, or traveled
internationally prior to their disease onset. Group 4 ORF3a mutants were
subsequently found in several other countries, including Singapore, South Korea, the
United Kingdom and Italy. It should be noted that this mutant virus strain appears to
be the most prevalent form of SARS-COV-2 in France, Italy,Brazil, and Singapore
(Figure C).
Virus genome data from France indicate that SARS-CoV-2 strains carrying
ORF3a:c.752gGt>gTt often have a S:c.1099Gtc>Ttc mutation in their S gene, which
interacts with ACE2 to mediate viral entry into its host cells
, and is regarded as acritical factor for viral transmission and virulence
4, 5. It is not clear if this mutationenhances host cell entry but this information
would be of great importance in assessing the potential for increased virulence
of Group 4 SARS-CoV-2 strains carrying this mutation. It is also not known how common
this mutation is in Group 4 viral isolates from different geographical regions.