Since the emergence of the new coronavirus, called SARS-CoV-2, several researchers have proposed that there is more than one strain, and that mutations have led to changes in how infectious and deadly it is. However, opinions are divided.
Genetic mutations are a natural, everyday phenomenon. They can occur every time genetic material is copied.
When a virus replicates inside the cell it has infected, the myriad of new copies will have small differences. Why is this important?
When mutations lead to changes in how a virus behaves, it can have significant consequences. These do not necessarily have to be detrimental to the host, but in the case of vaccines or drugs that target specified viral proteins, mutations may weaken these interactions.
Since the emergence of SARS-CoV-2, several research studies have highlighted variations in the virus’s genetic sequence. This has prompted discussion about whether or not there are several strains, if this has an impact on how easily the virus can infect a host, and whether or not this affects how many more people are likely to die.
Many scientists have called for caution. In this Special Feature, we summarize what researchers currently know about SARS-CoV-2 mutations and hear from experts about their views on what these mean for the pandemic.
SARS-CoV-2 is an enveloped RNA virus, which means that its genetic material is encoded in single-stranded RNA. Inside a host cell, it makes its own replication machinery.
RNA viruses have exceptionally high mutations rates because their replications enzymes are prone to errors when making new virus copies.
Virologist Prof. Jonathan Stoye, a senior group leader at the Francis Crick Institute in London in the United Kingdom, told Medical News Today what makes virus mutations significant.
“A mutation is a change in a genetic sequence,” he said. “The fact of a mutational change is not of primary importance, but the functional consequences are.”
If a particular genetic alteration changes the target of a drug or antibody that acts against the virus, those viral particles with the mutation will outgrow the ones that do not have it.
“A change in a protein to allow virus entry into a cell that carries very low amounts of receptor protein could also provide a growth advantage for the virus,” Prof. Stoye added.
“However, it should be stressed that only a fraction [of] all mutations will be advantageous; most will be neutral or harmful to the virus and will not persist.”
“Mutations in viruses clearly do matter, as evidenced by the need to prepare new vaccines against [the] influenza virus every year for the effective prevention of seasonal flu and the need to treat HIV-1 simultaneously with several drugs to [prevent the] emergence of resistant virus.”
– Prof. Jonathan Stoye
MNT recently featured a research study by a team from Arizona State University in Tempe. The paper described a mutation that mimics a similar event that occurred during the SARS epidemic in 2003.
The team studied five nasal swab samples that had a positive SARS-CoV-2 test result. They found that one of these had a deletion, which means that a part of the viral genome was missing. To be precise, 81 nucleotides in the viral genetic code were gone.
Previous research indicated that similar mutations lowered the ability of the SARS virus to replicate.
Another study, this time in the Journal of Translational Medicine, proposed that SARS-CoV-2 had picked up specific mutation patterns in distinct geographical regions.
The researchers, from the University of Maryland in Baltimore and Italian biotech company Ulisse Biomed in Trieste, analyzed eight recurr