Coronavirus- How the N439K variant escapes immune system’s antibodies

Context

• Scientists have assessed a mutation in the novel coronavirus and found that it confers the virus resistance to some individual's serum antibodies.

What is the new variant and mutation?

• Variants carrying this mutation are similar to the wild-type novel coronavirus from Wuhan, China in their ability to spread and cause disease.
• They can bind more strongly to the human ACE2 receptor which acts as the gateway for the virus to enter host cells.
• A single molecule part of the virus spike protein is altered from the amino acid asparagine to lysine, enabling the formation of a new point of contact with the ACE2 receptor.
• This alteration takes place in the 439th position of the protein's chain of amino acid building blocks.
• It is in line with a two-fold increase in its binding affinity with ACE2.

How the mutation is negative for immunity?

• The mutation both improves interaction with the viral receptor ACE2 and evades antibody-mediated immunity
• While the N439K mutation did not change virus replication, it significantly diminished binding of a proportion of both clinical antibodies and serum samples.
• The mutation particularly resisted neutralization.