From B.1.1.7. to B.1.617

In Hong Kong, there have been some worries about another outbreak of COVID-19 due to a recent case, which was confirmed to be imported from India. According to a study by Dr Gilman Siu from the Hong Kong Polytechnic University, this variant did not contain the N501Y mutation, which was found in the variants identified in the United Kingdom (B.1.1.7), South Africa (B.1.351), and Brazil (P.1); instead, it contained other important mutations, such as L452R and E484Q, whose co-existence was reported for the first time in India. Yet, more information is required to tell whether the catastrophic outbreak in India is caused by that ‘double mutant’ B.1.617.

Referring to Cherian et al (2021), B.1.617 contained a number of mutations of the spike protein of the virus; some of which were identified before. Amongst the mutations, L452R and E484Q may facilitate the binding of the viral particles to the host cells. If we refer to the mutation position 484, for example, E484K was also present in 501.V2 (lineage B.1.351). Although E484K was known to make the virus more infectious and it could make monoclonal antibody treatments less effective, we are still unable to conclude that E484Q shares similar properties (more solid findings are required to prove). On the other hand, for L452R, it could also negatively affect monoclonal antibody treatments, as described by the Centers for Disease Control and Prevention.

One might start to wonder if the mutations (L452R and E484Q) could also affect the effectiveness of the vaccines? Gratefully, with reference to a study by Yadav et al (2021), the sera isolated from vaccinated people were still able to neutralize B.1.617; in theory, vaccination is going to produce numerous monoclonal antibodies or the antibodies are ‘polyclonal’ in nature, which should target at multiple sites on the surface of the viral particles. Even though a single monoclonal antibody turns out to be less effective, there is still a family of similar antibodies to neutralize the virus. Nonetheless, it is a matter of fact that the virus is evolving, the vaccines should be updated regularly as in the case of influenza.

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