The D614G mutation in the spike protein of the novel coronavirus renders it up to eight times more infectious in human cells than the initial virus that originated in China, according to a study.

The spike protein is used by SARS-CoV-2, the virus which causes COVID-19, to enter the host cells.

The research, published in the journal eLife, confirms findings that D614G -- one of several mutations in the concerning variants that have emerged in the UK, South Africa, and Brazil -- makes the coronavirus more transmissible.

"The mutation has reached near-universal prevalence and is included in all current variants of concern," said Neville Sanjana, assistant professor of biology at New York University (NYU) in the US.

"Confirming that the mutation leads to more transmissibility may help explain, in part, why the virus has spread so rapidly over the past year," said Sanjana.

The researchers noted that the D614G mutation in the coronavirus spike protein likely emerged in early 2020, and is now the most prevalent and dominant form of the virus in many countries around the world.

Scientists have been working to understand the functional significance of these mutations and whether they meaningfully change how infectious or deadly the virus is.

In the latest study, the researchers introduced a virus with the D614G mutation into human lung, liver, and colon cells.

They also introduced the version of the virus without the mutation found early on in the pandemic into these same cell types for comparison.

The team found that the D614G variant increased transmissibility of the virus up to eight-fold as compared to the original virus.

The researchers also found that the spike protein mutation made the virus more resistant to being split by other proteins.

This provides a possible mechanism for the variant's increased ability to infect cells, as the hardier variant resulted in a greater proportion of intact spike protein per virus, they said.

"The D614G variant infects human cells much more efficiently than the wild type," said Zharko Daniloski, a postdoctoral fellow in Sanjana's lab at NYU and the New York Genome Center.

The findings support a growing consensus among scientists that the D614G variant is more infectious, the researchers said.

They noted that findings on the increased transmissibility of the D614G variant may influence COVID-19 vaccine development.

It may be beneficial for future booster shots to include diverse forms of the spike protein from different circulating variants, according to the researchers.

This is because the vaccines with emergency use authorisation, as well as those under development, were created using the original spike sequence, they said.

Studies are underway to understand how well these vaccines protect against the variants that emerged in the UK, South Africa, and Brazil, all of which contain the D614G mutation.