The form of SARS-CoV-2 that spread like wildfire across Europe before taking over North America features a mutation that makes the virus more transmissible than the form that spread in the early days of the pandemic, according to new research.
It’s all to do with the coronavirus’ spike, the protein used by the virus that acts as a “key” to enter cells and infect the human body. Biologists led by the Los Alamos National Laboratory looked at different genetic sequences of the virus taken from patients throughout the pandemic and identified 14 changes that have affected the spike protein.
Most notably, they pinpoint a mutation called D614G, described by the researchers as an “urgent concern”. The earliest D614G mutation in Europe was identified in Germany on January 28. They found that the coronaviruses bearing the mutation spike D614G spread rapidly in Europe around early February, replacing the original Wuhan form of the virus rapidly and becoming the dominant form of the virus. Additionally, the mutated D614G form was introduced into both Canada and the USA around early March, and by the end of March it had taken over to become the dominant form in both nations.
"The mutation Spike D614G is of urgent concern; it began spreading in Europe in early February, and when introduced to new regions it rapidly becomes the dominant form,” the authors write in the paper available to read on preprint server BioRxiv.
“We were concerned that the D614G mutation can increase transmissibility,” they explain. Although the mutation appears to make the virus more transmissible, the researchers say there was "no significant correlation" between people infected with the D614G form and the risk of hospitalization, suggesting it hasn't made people more severely ill than other forms of the virus.
While some scientists have described the research as "fascinating," others have warned that the findings should be interpreted with caution.
The research was posted on April 30 on BioRxiv, a preprint server that allows researchers to share their work before it is peer-reviewed. The peer-review process helps to ensure the research has a high standard of quality and validity, but many scientists are opting to publish their work in this way to speed up discussion and collaborations with scientists working on Covid-19 vaccines or treatments.
Experts in the field, who are not involved with the study, have shown interest in the findings, but have been quick to highlight the study's drawbacks and say that further research is required before we can reach any solid conclusions.
“This is a fascinating story of SARS-CoV-2 evolution employing tools honed in the analysis of two completely different viruses, HIV-1 and influenza,” commented Dr Jonathan Stoye, Head of Division of Virology at The Francis Crick Institute, who was not involved in the study.
“Although the functional significance of the changes observed have yet to be fully characterised, the study shows that SARS-CoV-2 can alter its genetic structure in multiple ways as it spreads around the world, a finding likely to have important implications for vaccine development.”
Professor Peter Hotez, co-director of Texas Children’s Hospital Center for Vaccine Development, described the research as “noteworthy,” but added: “there is a lot of speculation here. They have no experimental verification,” according to the Los Angeles Times.
Francis Collins, director of the National Institutes of Health, told the Washington Post that the paper “draws rather sweeping conclusions.”