#Antibody #evasion and receptor binding of #SARS-CoV-2 variants #PQ.16.1.1 and RK.1

 

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Since its rapid global spread beginning in late 2024, the SARS-CoV-2 variant NB.1.8.1 has progressively displaced older omicron variants, and has established near-total dominance in Asia. More recently, two NB.1.8.1-derived sublineages, PQ.16.1.1 and RK.1, have emerged and expanded substantially, particularly in China and Singapore (...). Specifically, the sublineage PQ.16.1.1 acquired the amino acid substitutions Asp253Gly (within the N-terminal domain), alongside Asn417Thr, Asp420Asn, and Ile478Thr (within the receptor-binding domain) relative to the parental NB.1.8.1 strain (...). Concurrently, the RK.1 sublineage (formally classified as a descendant of the PQ.17.7.2.1 branch) acquired Asp420Asn, His445Pro, and Ile478Thr (...). Furthermore, PQ.16.1.1 has continued to evolve into the SV series sublineages (predominantly SV.2 and SV.2.1), which have maintained all receptor-binding domain mutations, including Asp420Asn, and have subsequently come to dominate the circulating SARS-CoV-2 strains in Singapore (...).

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In summary, the convergent acquisition of the Asp420Asn substitution in NB.1.8.1 sublineages again illustrates a classic SARS-CoV-2 receptor-binding domain evolution trade-off: a sacrifice in hACE2 receptor engagement in exchange for profound, targeted evasion of class 1 neutralising antibodies. (...) Given the increased evasion of class 1 antibodies by these Asp420Asn-carrying sublineages, these variants will likely spread from Asia and begin to prevail in countries where mRNA vaccination is common and populations are enriched with class 1 neutralising antibodies. 

Source: 

Link: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(26)00429-9/fulltext?rss=yes

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