Coronavirus mutant form, known as D614G, identified in genetic samples collected in the Xinfadi food market in Beijing, began spreading in Europe in early February and has become the world's dominant strain by May. According to a report by the South China Morning Post, D614G is seen in 70% sequence samples in Europe and North America.
However, a new study says that antibodies from recovered patients in China failed to stop the new strain, which poses a threat to them, scientists said in their paper published in Biorxiv.org. Therefore, these people may still be vulnerable to a mutant form of the pathogen spreading in other countries.
Professor Huang Ailong from Chongqing Medical University said there is an urgent need to determine what threat this mutation possibly brings to recovered patients.
Beijing has recorded 227 new infections since the latest coronavirus outbreak, and more than 2.3 million residents have been tested to control the spread of the virus.
Health officials have identified the new strain in many locations at the market, including inside the salmons' mouths. At the same time, the first three patients that have been released have also contained the D614G mutation.
Increase in Viral Infectivity in Humans
The researchers, headed by Huang, selected a strain of the virus from the previously circulated in China and then manipulated it to create a man-made version that contains the mutation. Afterwards, they extracted antibodies from 41 blood samples collected from recovered patients and tested them against the mutant.
D614G mutation has been identified by a report published last week by a medical research facility in San Diego, known as Scripps Research, to have the potential of increasing the number of spike proteins on the coronavirus and boost its infectivity on human cells by a factor of 10.
But that estimation is mostly based on computer modelling so questions remained over the possibility that the new strain has a stronger binding efficiency.
On the other hand, the Chongqing study revealed that the antibodies collected from the three patients failed to stop the mutated strain. One sample even showed almost zero effect.
Furthermore, the researchers found that the mutant's entry efficiency was 2.4 times higher when they tried to infect host cells with the mutant and normal strains.
According to the researchers, though the increase in entry activity is small, it could still cause a large difference in viral infectivity in the human body.
Mutant Strain's Detrimental Effect on Vaccine Development
Researchers are concerned that the prevalence of D614G could have a detrimental impact on vaccine development.
The race of finding a vaccine against the virus continues, such as those Chinese vaccine candidates that have entered their final phase of clinical trials.
However, like those under development in the United States and Europe, which are based on the earliest strains of the coronavirus detected and sequenced in Wuhan, studies found that their effectiveness could be reduced.
Huang said: "Given the evolving nature of the SARS-CoV-2 RNA genome, antibody treatment and vaccine design might require further consideration to accommodate the D614G and other mutations that may affect the immunogenicity of the virus."
According to Beijing health authorities, 10% of the people infected with the new outbreak in Beijing are in critical conditions. They have already flown medical experts from across the country to help with the aid effort.
