Exploring the 4 Menacing COVID-19 Variants of 2023.
Here are the most noteworthy COVID-19 variants in 2023.
The year 2023 has seen the emergence and spread of several new variants of SARS-CoV-2, the virus that causes COVID-19. These variants have different characteristics that affect their transmissibility, severity, and immune escape.
Some of these variants have been given unofficial nicknames by the media or the public, such as Kraken, Arcturus, Eris, Flip and Pirola. In this article, we will review the main features of these variants and how they impact the global response to the pandemic.
1. Kraken (XBB.1.5)
XBB.1.5, also known as Kraken, is a subvariant of the Omicron variant of SARS-CoV-2, the virus that causes COVID-19. It is a hybrid virus that resulted from the recombination of two other Omicron subvariants: BA.2.75 and BA.2.10.1. XBB.1.5 has many mutations in the spike protein, which is the part of the virus that attaches to human cells and allows infection.
The most distinctive mutation in XBB.1.5 is F486P, which is located at a site on the spike protein that is important for binding to the human ACE2 receptor. This mutation gives XBB.1.5 a significant advantage over its parent lineage XBB, which had a different mutation at the same site (F486S).
F486S helped XBB evade the immune system by changing the shape of the spike protein and making it less recognizable by antibodies. However, F486S also reduced XBB’s ability to infect human cells by weakening its binding affinity to the ACE2 receptor.
F486P restores this binding affinity while retaining the immune evasion property of F486S. In other words, F486P makes XBB.1.5 more transmissible and more immune evasive than XBB.
In addition to F486P, XBB.1.5 also has other mutations that are similar to those found in other variants. These mutations may also contribute to XBB.1.5’s increased transmissibility and immune evasion by enhancing its stability, infectivity, or antibody resistance. Some examples of these mutations are N501Y, E484K, K417N, L452R, and P681R.
2. Arcturus (XBB.1.16)
Arcturus was detected in India in late January 2023 and has since spread to some other parts of Asia, but it has not become dominant in any region. Arcturus has a different spike amino acid profile than Omicron, which affects its transmissibility and immune evasion.
In addition to F486P advantages mentioned under Kraken, Arcturus also has other mutations that are similar to those found in other variants of concern, such as Alpha, Beta, Gamma, and Delta.
These mutations may also contribute to Arcturus’s increased transmissibility and immune evasion by enhancing its stability, infectivity, or antibody resistance. Some examples of these mutations are:
- N501Y: This mutation is located at a site on the Receptor-binding domain (RBD). N501Y increases the binding affinity and stability of the RBD, making it easier for the virus to infect human cells. N501Y also helps the virus evade some neutralizing antibodies that target this site. N501Y was first seen in Alpha and later in Beta, Gamma, and Omicron.
- E484K: This mutation is located at a site on the RBD that is targeted by many neutralizing antibodies. E484K changes the charge and shape of the RBD, making it less recognizable by antibodies. E484K also increases the binding affinity of the RBD to the ACE2 receptor. E484K was first seen in Beta and later in Gamma and Omicron.
- K417N: This mutation is located at a site on the RBD that is adjacent to E484K and is also targeted by many neutralizing antibodies. K417N changes the charge and shape of the RBD, making it less recognizable by antibodies.
3. Eris (EG.5)
Eris is a descendant lineage of XBB, which has the same spike amino acid profile as XBB.1.5. Eris was designated as a variant under monitoring (VUM) in July 2023.
Within the Eris lineage, the subvariant EG.5.1 has an additional spike mutation Q52H compared to Kraken and represents 78% of the available sequences for Eris and its descendant lineages.
Eris is more transmissible and more immune evasive than previous versions of the virus. Eris is also possibly more resistant to some of the existing vaccines and treatments for COVID-19 than XBB.1.5, but they still provide some protection against severe disease and death caused by this variant.
However, Eris does not appear to cause more severe illness or death than other variants.
Eris quickly became dominant in some regions by late 2023, accounting for nearly a quarter of all sequences reported to GISAID.
FLip mutations are unique to the Eris and its sub-lineages. The L455F and F456L mutations are nicknamed FLip mutations because they switch the positions of two amino acids on the spike protein labeled F and L.
They were predicted months ago as a likely consequence of the widespread use of monoclonal antibodies to treat COVID-19 infections. The FLip mutations are suspected to affect the behavior of the virus and may contribute to its ability to evade neutralizing antibodies.
4. Pirola (BA.2.86)
Pirola is a sub-lineage of Omicron (BA.2) that was first detected in Denmark and Israel in July 2023 and later reported in several other countries. Pirola was designated as a variant under monitoring by the World Health Organization in August 2023.
Pirola has acquired more than 30 mutations in its spike protein, the part of the virus that binds to human cells and initiates infection. This reminds people of how omicron became a big deal in November 2021 with sudden changes in its genome.
It is more infectious and can cause breakthrough infections among people who previously had COVID-19 or received COVID-19 vaccines. However, Pirola does not appear to cause more severe illness or death than other sub-lineages.
Pirola is also more resistant to some of the existing vaccines and treatments for COVID-19 than Omicron, but they still provide some protection against severe disease and death caused by this sublineage.
Conclusion
In the year 2023, the emergence and spread of several new variants of SARS-CoV-2 posed new challenges to the global response to the pandemic, affecting the transmissibility, severity, and immune escape of the virus.
Despite their impact on the effectiveness of vaccines and treatments, it’s important to note that vaccines still offer protection against severe disease and death caused by these variants.
Therefore, it’s crucial to get vaccinated as soon as possible and follow public health measures such as wearing masks, avoiding crowds, and practicing physical distancing to prevent the spread of these variants.
By doing so, we can all contribute to the fight against COVID-19 and pave the way for a safer and healthier future.
