The evolutionary traits of the Lambda variant, giving it both greater transmissibility and immune escape abilities make it possibly the most dangerous variant so far, according to a new study published on the bioRxiv preprint server.
Mutations present in the Spike (S) protein seen in many variants of concern (VOCs) and variants of interest (VOI) allow them to be resistant to the neutralising antibodies (NAbs) from COVID vaccination or infection.
The Lambda variant is predominantly spreading in South American countries. According to the Global Initiative on Sharing All Influenza Data (GISAID) database, the Lambda variant has been reported in 26 countries worldwide. Chile, despite its vaccination rate of 60% saw a surge in COVID cases due to the Lambda variant, due to its immune escape capability.
Lambda variant’s evolutionary traits
In this study, which is awaiting peer review as a preprint, the researchers reported that insertion of the N246-253RSYLTPGD mutation in the NTD of the Lambda S protein is associated with the increased virulence. This mutation is responsible for the rapid spread of the Lambda variant in the Southern American countries.
The authors of this study have indicated two of the critical virological features of the Lambda variant, namely, a) resistance to viral-induced immune responses due to the RSYLTPGD246- 253N, L452Q, and F490S mutations and b) enhancement in transmissibility due to the T76I and L452Q mutations.
This study found that the Lambda S is more resistant to the vaccine-induced antisera compared to the Lambda+N246-253RSYLTPGD S derivative. Another key finding is that RSYLTPGD246-253N mutation overlaps with a component of the NTD “supersite” indicating that it is the immunodominant site. Mutation of this site has therefore enabled the Lambda variant to escape immunity conferred by COVID vaccination.
The comparative study between the parental D614G S strain and the Lambda variant has shown significantly higher infectivity in the latter viral strain.
This study confirms other studies’ finding of increased infectivity of the Lambda, Delta and Epsilon variants is due to the L452Q/R mutation. However, higher infectivity does not guarantee a rapid spread, as seen with the Epsilon variant which failed to spread in the human population despite high infectivity.
This caused the to WHO drop it from the VOC/VOI classification on July 6, 2021. In order to understand if a variant would infect a large number of people, it is essential to determine if it has increased viral infectivity and evasion from the immune response. This study revealed that the Lambda variant possesses both these virological features.
Source: News-Medical.Net
Journal information: “SARS-CoV-2 Lambda variant exhibits higher infectivity and immune resistance,” Izumi Kimura, et al., bioRxiv, 2021.07.28.454085; doi: https://doi.org/10.1101/2021.07.28.454085
