Variants Flashcards
UK variant
In the time that SARS-CoV-2 has troubled humans, it’s accumulated innumerable mutations. Those that matter have one of two key features: they either help the virus latch onto and enter cells more easily, or they allow it to better evade tagging and destruction by the immune system. Today, scientists are following three variants of particular concern: B.1.1.7, originally detected in the U.K.; B.1.351, from South Africa; and P.1, from Brazil. Predictably, variants seem to have emerged more quickly in countries with rampant viral spread—places where the virus has had more chances to replicate, mutate, and hit upon changes that confer an evolutionary advantage. The U.K.’s B.1.1.7 variant has spread to more than eighty countries and has been doubling every ten days in the U.S., where it is expected to soon become the dominant variant. Its key mutation is called N501Y: the name describes the fact that the amino acid asparagine (“N”) is replaced with tyrosine (“Y”) at the five-hundred-and-first position of the spike protein. The mutation affects a part of the spike that allows the virus to bind to cells, making the variant some fifty per cent more transmissible than the original; new evidence also suggests that people infected with it have higher viral loads and remain infectious longer, which could have implications for quarantine guidelines.
Mutations
