SARS-CoV-2 continues to accumulate mutations to evade immunity, leading to an increasing incidence of breakthrough infections after vaccination. Thus, different variants, from China but also from the United States are of concern to global and European health agencies. Despite the success of the first generations of SARS-CoV-2 vaccines, viral evolution and increasing immune escape from the virus make the development of more broadly protective next-generation vaccines urgent. The team from Wuhan University retraces here in the journal Science Translational Medicine, via the analysis of millions of sequences, the evolutionary history of the S protein of SARS-CoV-2.

At the end of this broad search, “Span”, a new vaccine antigen which appears to elicit a broader neutralizing antibody response than a wild-type S-protein vaccine of SARS-CoV-2. The first proof of concept is provided here in mice, with the hope of a universal vaccine, that is to say capable of thwarting the antigenic drift of the virus.

Many Variants Are of Concern to The Authorities Today

Latest World Health Organization (WHO) Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE) Meeting on January 4, 2023 Reveals Continued Predominance of Omicron BA Lineages .5.2 and BF.7 among locally acquired infections. Lines BA.5.2 and BF.7 together accounted for 97.5% of all local infections according to genomic sequencing. No new variants or new mutations were identified in the data.

Furthermore, the latest report from the European Centers for Control (ECDC) raises concerns that XBB.1.5 is a subline of XBB with an additional peak RBD mutation (S486P). This lineage was first detected in the United States and then detected in several other countries, including countries in Europe (Denmark, France, Austria, Netherlands, Germany, Italy, Spain, Sweden, Iceland, Belgium , Czechia, Portugal and Ireland). This line appears to have “a great growth advantage” over previously circulating lines.

It will be understood that anticipating the evolutionary trajectory of the virus in advance, for the design of new generation vaccines is complex and requires constant global monitoring.

The in-depth study of 11,650,487 SARS-CoV-2 sequences brings us brand new clues: the spike protein (S) of SARS-CoV-2 does not evolve “randomly”, but follows directions of high infectivity, weaker immune escape or, conversely, lower infectivity and stronger immune escape. Thus, the analysis reveals that: the Omicron variant has a higher immune escape capacity but a high infectivity than in only one of the cell lines tested.
From these fine data on the evolution of the virus, the Chinese team was able to develop “Span”, a new vaccine antigen which includes fragments which reflect the evolution of the virus, and which seems to induce a broader neutralizing antibody response than a wild-type SARS-CoV-2 S-protein vaccine.

When given to mice, Span elicited a more effective neutralizing antibody response than current vaccines, and appears to provide substantial protection against Beta, Delta and Omicron variants.

Together, these data support the further development of Span as a vaccine antigen.
The scientists evoke “the feasibility of a universal vaccine to combat the antigenic drift of SARS-CoV-2”.

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