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#Virological characteristics of the #SARS-CoV-2 #NB181 #variant

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By G.M.

{Excerpt}

After the spread of SARS-CoV-2 JN.1, its subvariants, such as KP.3 (JN.1.11.1.3)1 and KP.3.1.1 (JN.1.11.1.3.1.1),2 and XEC (a recombinant lineage of two JN.1 subvariants),3 emerged and rapidly spread globally. Subsequently, LP.8.1 (JN.1.11.1.1.1.3.8.1),4 a descendant lineage of KP.1.1.3 (JN.1.11.1.1.1.3), accounts for approximately 30% of all global infections as of April, 2025, as per data from Nextstrain. Thereafter, NB.1.8.1 (XDV.1.5.1.1.8.1), a descendant lineage of XDV, has started to spread worldwide. XDV is a recombinant lineage of XDE (a recombinant lineage of GW.5.1 [XBB.1.19.1.5.1] and FL.13.4 [XBB.1.9.1.13.4]) and JN.1. NB.1.8.1 has acquired seven spike substitutions and 23 non-spike substitutions compared with JN.1 (appendix pp 15–16). Compared with the XEC spike protein, the NB.1.8.1 spike bears four substitutions: G184S, K478I, A435S, and L1104V (appendix pp 15–16). We estimated the relative effective reproduction number (Re) of NB.1.8.1 using a Bayesian multinomial logistic model1–4 based on genome surveillance data from Singapore, Hong Kong, Australia, and the USA, where this variant has spread as of April, 2025 (appendix pp 9–13, 15–16). The Re of NB.1.8.1 was 1·17-fold higher than that of LP.8.1 in Singapore, suggesting its potential to outcompete the other major SARS-CoV-2 lineages (appendix pp 15–16).

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