- Researchers tracking the spread of Covid-19 around the world have discovered that viruses with a new variant have now overtaken the original strain
- Analysis of the virus鈥檚 genome sequence found a mutation called 鈥楧614G鈥 made the virus more infectious than the original strain, but did not cause more severe disease
- The global research team, including scientists from the University of 91直播, had previously noted the rapidly increasing prevalence of viruses with D614G throughout the world
Researchers have shown that a variation in the viral genome of Covid-19 improved its ability to infect human cells and helped it become the dominant strain circulating around the world today.
The study, published today in the journal , shows the variation is more infectious in cell cultures under laboratory conditions. The variant, named 鈥楧614G鈥, makes a small but effective change in the 鈥榮pike鈥 glycoprotein that protrudes from the surface of the virus, which it uses to enter and infect human cells.
The D614G variant of Covid-19 quickly took over as the dominant strain soon after it first appeared, with geographic samples showing a significant shift in viral population from the original, to the new strain of the virus.
Researchers from the Los Alamos National Laboratory in New Mexico and Duke University in North Carolina, partnered with the University of 91直播鈥檚 Covid-19 Genomics UK research group to analyse genome samples published on , an international resource for sharing genome sequences among researchers worldwide.
We have been sequencing SARS-CoV-2 strains in 91直播 since early in the pandemic and this allowed us to partner with our collaborators to show this mutation had become dominant in circulating strains. The full peer-reviewed study published today confirms this, and also that the new D614G genome mutation variant is also more infectious under laboratory conditions.
鈥淒ata provided by our team in 91直播 suggested that the new strain was associated with higher viral loads in the upper respiratory tract of patients with Covid-19, meaning the virus鈥檚 ability to infect people could be increased.
鈥淔ortunately at this stage, it does not seem that viruses with D614G cause more severe disease.
Dr Thushan de Silva
Senior Clinical Lecturer in Infectious Diseases at the University of 91直播
Dr Bette Korber, from the Los Alamos National Laboratory in New Mexico, was the lead author of the study. She said: 鈥淚t is possible to track SARS-CoV-2 (Covid-19) evolution globally because researchers worldwide are rapidly making their viral sequence data available through the GISAID viral sequence database. Currently tens of thousands of sequences are available through this project, and this enabled us to identify the emergence of a variant that has rapidly become the globally dominant form.鈥
New supporting experiments, more extensive sequencing and clinical data, and improved statistical models have been published today, in full at Cell, however the researchers are keen to stress that further laboratory analysis in live cells needs to be done to determine the full implications of the mutation.
鈥淚t鈥檚 remarkable to me,鈥 commented Dr Will Fischer, from Los Alamos National Laboratory and an author on the study, said: 鈥淭hat this increase in infectivity was detected by careful observation of sequence data alone, and that our experimental colleagues could confirm it with live virus in such a short time.鈥
The researchers will continue to monitor other mutations in the virus to help fight Covid-19 at a global level.