By Nana Dadzie Ghansah
The Variant of Concern 202012/01 (VOC-202012/01), also known as Variant Under Investigation in December 2020 (VUI — 202012/01), and Lineage B.1.1.7 is a variant of SARS-CoV-2 that was first detected in Kent County of the UK in September 2020.
In November, public health officials in the UK were stumped as to why cases in Kent county were increasing despite national restrictions. Through genomic studies, they found the new variant to cause a much faster spread of COVID-19.
How did this variant come about?
Through 23 mutations. Seventeen (17) of these mutations led to changes in viral proteins, while six did not. The mutations are in the spike protein (S), the nucleocapsid (N), and two other proteins — ORF1ab and ORF8.
Are these mutations concerning?
Viruses mutate to escape the effect of antivirals, the immune system and adapt to their environments. Although over 4000 mutations in the SARS-CoV-2 genome have been found, these new ones are noteworthy. There are eight of them alone in S, of which three are concerning.
The first and most concerning mutation is called N501Y.
This mutation came about because, at position 23,063 of the viral genome, the nucleotide Adenosine was replaced by Thymine. This led to a change in amino acids at position 501 in the spike protein. Instead of Asparagine (N), this variant has Tyrosine (Y). Hence N501Y.
The amino acid at position 501 plays a crucial role in how the virus binds to the human ACE receptor. This mutation makes the virus bind even better.
In a study by Gu et al., the N501Y mutation was induced in a mouse by passing the virus several times through the rodent. The variant was found to be more virulent. (Science 369 (6511): 1603–7).
The second concerning mutation is called P681H.
This one came about because, at position 23,604 of the viral genome, Cytosine was replaced by Adenosine. This led to a change in amino acids at position 681 of the spike protein. Histidine replaced Proline — P681H.
This amino acid is adjacent to the site where the enzyme Furin cleaves S1 of the spike protein from S2…