Research shows how the G614 variant of the new coronavirus increased the microorganism’s ability to replicate without increasing its lethality.
A study led by Duke University, the Los Alamos National Laboratory, and the La Jolla Institute (LJI), all in the United States, reveals how the G614 variant of the new coronavirus became responsible for the majority of Covid-19 cases worldwide. According to the scientists, a mutation helped Sars-CoV-2 to replicate, increasing the viral load present in patients and allowing it to spread more easily – but without becoming more lethal. The results were published in the scientific journal Cell on Thursday (2).
The scientists analyzed two variants that circulated among patients in San Diego, California, in mid-March: G614 and D614, which have only a small difference in their spike protein – the protein that enables the virus to enter human cells.
Under the guidance of Erica Ollmann Saphire, professor at LJI, and David Montefiore, Ph.D. at Duke University Medical Center, the researchers found that viruses that carry the G mutation in the spike protein replicate two to three times more efficiently, resulting in a higher viral load.
The next step was to analyze whether the G mutation is more difficult to be fought by the immune system than the D variant. Scientists used samples from six San Diego residents and, fortunately, human immune responses demonstrated the ability to neutralize the G mutation as well or even better than D variant. Although G mutation spreads more easily, there was no need for an increase in antibody production or the production of better antibodies to neutralize it.
In addition, previous studies have shown that carrying the G variant is not associated with greater disease severity. “Clinical data from a University of Sheffield article showed that, although patients with the new G virus have more copies of the virus than patients infected with D, there was no corresponding increase in the severity of the disease,” said Saphire, of the LJI.
According to the professor, the main “objective” of the virus is to spread more efficiently and, for that reason, it is more advantageous to keep the hosts alive. “The virus doesn’t ‘want’ to be more lethal. It ‘wants’ to be more transmissible,” said Saphire. “A virus ‘wants’ you to help it spread copies of itself. It ‘wants’ you to go to work and school and social gatherings and transmit it to new hosts.
Of course, a virus is inanimate—it doesn’t ‘want’ anything. But a surviving virus is one that disseminates further and more efficiently. A virus that kills its host rapidly doesn’t go as far—think of cases of Ebola. A virus that lets its host go about their business will disseminate better—like with the common cold.”
With this in mind, the researchers emphasize the importance of using face masks and social distancing as ways to fight Sars-CoV-2. The study also contributes to the development of vaccines against the new coronavirus, since it is essential to discover which mutations of the microorganism are circulating and how they interact with our immune system.