COVID-19 Lambda variants’ recombinant protein and immune escape

According to the information provided by WHO, the Spike protein of the Lambda mutant strain has mutation sites such as G75V, T76I, del247/253, L452Q, F490S, D614G, and T859N. These sites may affect the transmission ability and immune escape ability of the mutant strain. .

Lambda and Delta coincidentally both had mutations at position L452, which may indicate that mutations at this position may have caused the rapid spread of these two viruses.

According to a paper published in the preprint bioRxiv by researchers from the University of Tokyo on July 28, the Lambda mutant strain has two key viral characteristics:

1. RSYLTPGD246-253N, L452Q and F490S mutations lead to enhanced immune escape ability;

2. Mutations of T76I and L452Q lead to increased infectivity.

In addition, under the background that vaccines have been widely vaccinated, people are very concerned about whether the virus can escape the protective effect produced by the vaccine. Recently, two studies have studied the immune escape ability of Lambda. 

For example, a study in the United States found that compared with wild-type strains, serum samples from recovered patients and vaccinated serum samples only decreased Lambda’s neutralizing activity by 2-3 times. A study in Chile found that the neutralizing activity of serum samples vaccinated with SINOVAC vaccine decreased by 3.05 times.

Therefore, the existing vaccine still has a protective effect on the mutant strain.

However, the Lambda mutant strain has just emerged, and there are few related studies and reports, and more experiments are needed by scientific researchers in order to have a more in-depth understanding of this potentially high-risk mutant strain.

Although the lack of a large segment of S-NTD has not yet become a mainstream change. However, some C.37 still carry this mutation. To facilitate the research of scientists. Yiqiao Shenzhou has separately developed two types of Spike products for the Lambda lineage, one type covers Spike protein with large deletions of S-NTD, and the other type is Spike protein product covering the latest C.37 mutations.

At present, the most concerned about the world is undoubtedly the Delta mutant strain. Since the Delta mutant strain was discovered in India at the end of last year, it has rapidly swept the world and became the main epidemic strain in most parts of the world. 

Moreover, many studies have shown that its infectious ability has greatly increased, and the protective effect of vaccines has also been significantly reduced.

The WHO has redefined the Delta mutation, and four lineages including B.1.617.2, AY.1, AY.2, and AY.3 are considered to be strains of concern. The two lineages AY.1 and AY.2, which introduced the K417N mutation in Delta, are named Delta plus. And K417N already exists in the previous Beta mutant strain.