Evolutionary rate of SARS-CoV-2 increases during zoonotic infection of farmed mink

Evolutionary rate of SARS-CoV-2 increases during zoonotic infection of farmed mink

Authors:
Ashleigh F. Porter (1*), Damian F.J. Purcell (1), Benjamin P. Howden (1,2), Sebastian Duchene (1*).

Affiliations:

  1. Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.
  2. Microbiological Diagnostic Unit Public Health Laboratory, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.
    *Corresponding author. Email: ashleigh.porter@unimelb.edu.au, sebastian.duchene@unimelb.edu.au

Abstract:
To investigate genetic signatures of adaptation to the mink host, we characterized the rate heterogeneity in mink-associated SARS-CoV-2. In 2020, the first detected anthropozoonotic spillover event of SARS-CoV-2 occurred in mink farms throughout Europe and North America. Both spill-back of mink-associated lineages into the human population and spread into surrounding wildlife was reported, highlighting the potential formation of a zoonotic reservoir. Our findings suggest the evolutionary rate of SARS-CoV-2 underwent an episodic increase upon introduction to the mink host before returning to the normal range. Furthermore, SARS-CoV-2 lineages could have circulated in the mink population for a month before detection, and during this period, evolutionary rate estimates of 6.57 ×10^(-3) could yield an 8-fold increase of mutations compared to the evolutionary rate of SARS-CoV-2 in humans. We suggest that SARS-CoV-2 undergoes a brief, but significant, increase in evolutionary rate in response to greater selective pressures during species jumps, emphasizing the necessity of monitoring zoonotic SARS-CoV-2 infections.

One-Sentence Summary:
In 2020, SARS-CoV-2 outbreaks were reported in mink farms. During this period of adaptation, the evolutionary rate of SARS-CoV-2 increased for a short interval.

Mink_MS.pdf (2.4 MB)