In the ASU study, researchers used a new technology at the university’s Genomics Facility known as next-generation sequencing to sift through the genome of SARS-CoV-2, the virus that causes COVID-19.
A May 6 release by ASU explains that more than 16,000 SARS-CoV-2 sequences have been added to German, nonprofit, scientific organization GISAID’s EpiCoVTM Database. The researchers used 382 nasal swab samples from possible COVID-19 cases in Arizona to identify a new SARS-CoV-2 mutation that had not been seen before. In one of the genomes, known as AZ-ASU2923, 81 DNA base pairs in a gene called ORF7a were deleted.
The ORF7a gene produces an accessory protein which assists the virus in infecting and replicating inside the human body. The protein is believed to help the virus bypass the immune system, allowing the virus to replicate and kill the cell before spreading to others.
“The viral protein is thought to help SARS-CoV-2 evade human defenses, eventually killing the cell,” the release explains. “This frees up the virus to infect other cells in a cascading chain reaction that can quickly cause the virus to make copies of itself throughout the body, eventually causing serious COVID-19 symptoms eight to 14 days after the initial infection.”
Deletion of the gene that produces the protein thus suggests that the virus may be weakening, similarly to the one that causes SARS.
“One of the reasons why this mutation is of interest is because it mirrors a large deletion that arose in the 2003 SARS outbreak," Efrem Lim, an ASU researcher and the lead study author, said in a statement accompanying the release. During the middle and late stages of the SARS epidemic, the virus underwent mutations that weakened it.
The ASU researchers are conducting additional experiments to “understand the functional consequences of the viral mutation,” the release states.
However, study co-author Matthew Scotch told the New York Post that it is too soon to definitely state that the COVID-19 coronavirus is weakening.
“The takeaway is that one virus had a large deletion which demonstrates that it is possible for the virus to transmit without having complete portions of its genetic material. This was one virus and we do not suggest that this means a ‘weakening’ of any kind,” Scotch said in an email.
Scotch also confirmed that there is nothing surprising about how the virus has mutated so far, noting that “differences in clinical outcomes are more about individual immune response and co-morbidities rather than the differences in the genomics of the virus.”
The latest study comes after a report published on April 30 by scientists at the Los Alamos National Laboratory (LANL) in New Mexico showed a new strain of the COVID-19 coronavirus that is more dominant and contagious than earlier varieties.
According to the researchers, the new strain first appeared some time in February in Europe and then migrated to the East Coast of the United States. Officials noted that the strain, referred to as mutation spike D614G, has been the globe’s dominant COVID-19 strain since mid-March.
