SARS-CoV-2: One virus, two types

SARS-CoV-2: One virus, two types

Apparently mutated SARS-CoV-2, Chinese researchers have identified two genetic variants. How different are they?

Research by Chinese researchers shows that there are apparently two genetic variants of the novel coronavirus.

L-type and S-type
Based on the analysis of 103 virus isolates, two genetic variants of SARS-CoV-2 can be differentiated, which are called L-type (L for leucine) and S-type (S for serine). They are distinguished by 2 single nucleotide polymorphisms (SNPs).

The researchers assume that the L-type is descended from the older S-type. The S-type probably originated at the time when the virus spread from animals to humans. The fact that the L-type is more common suggests that it is more "aggressive" than the S-type, the researchers said. They also speculate that therapy or quarantine measures shifted the relative frequency of L- and S-type shortly after the outbreak of SARS-CoV-2.

Functioning not different
However, these are extremely fine distinctions, as one biomedical scientist points out: "The differences between the two identified variants are tiny," Ian Jones of the University of Reading, Great Britain, told the New Scientist. In fact, they could not really be considered as separate strains. Many of the genetic differences would not affect protein expression and thus would not alter the way the virus works or the symptoms it causes, Jones is quoted further. One is no more lethal than the other.