Post by Nadica (She/Her) on Sept 5, 2024 19:49:13 GMT
Virological characteristics of the SARS-CoV-2 KP.2 variant - Published May 20, 2024
Abstract
The JN.1 variant (BA.2.86.1.1), arising from BA.2.86.1 with the S:L455S substitution, showed increased fitness and outcompeted the previous dominant XBB lineage by the beginning of 2024.1 JN.1 subsequently diversified, leading to the emergence of descendants with spike (S) protein substitutions such as S:R346T and S:F456L. Particularly, the KP.2 (JN.1.11.1.2) variant, a descendant of JN.1 bearing both S:R346T and S:F456L, is rapidly spreading in multiple regions as of April, 2024. Here, we investigated the virological properties of KP.2. KP.2 has three substitutions in the S protein including the two above and an additional substitution in the non-S protein compared with JN.1 (appendix p 15). We estimated the relative effective reproduction number (Re) of KP.2 based on the genome surveillance data from the USA, UK, and Canada, where more than 30 sequences of KP.2 have been reported, using a Bayesian multinomial logistic model (appendix pp 8–13, 15).2 The Re of KP.2 is 1·22-times, 1·32-times, and 1·26-times higher than that of JN.1 in the USA, UK, and Canada, respectively (appendix p 15). These results suggest that KP.2 has higher viral fitness and potentially becomes the predominant lineage worldwide. Indeed, as of the beginning of April, 2024, the estimated variant frequency of KP.2 has already reached 20% in the UK (appendix p 15).
We then did a neutralisation assay using monovalent XBB.1.5 vaccine sera and breakthrough infection sera with XBB.1.5, EG.5, HK.3, and JN.1 infections. In all cases, the 50% neutralisation titre against KP.2 was significantly lower than that against JN.1 (appendix p 15). Altogether, these results suggest that the increased immune escape ability of KP.2 contributes to its higher Re compared with JN.1.
Abstract
The JN.1 variant (BA.2.86.1.1), arising from BA.2.86.1 with the S:L455S substitution, showed increased fitness and outcompeted the previous dominant XBB lineage by the beginning of 2024.1 JN.1 subsequently diversified, leading to the emergence of descendants with spike (S) protein substitutions such as S:R346T and S:F456L. Particularly, the KP.2 (JN.1.11.1.2) variant, a descendant of JN.1 bearing both S:R346T and S:F456L, is rapidly spreading in multiple regions as of April, 2024. Here, we investigated the virological properties of KP.2. KP.2 has three substitutions in the S protein including the two above and an additional substitution in the non-S protein compared with JN.1 (appendix p 15). We estimated the relative effective reproduction number (Re) of KP.2 based on the genome surveillance data from the USA, UK, and Canada, where more than 30 sequences of KP.2 have been reported, using a Bayesian multinomial logistic model (appendix pp 8–13, 15).2 The Re of KP.2 is 1·22-times, 1·32-times, and 1·26-times higher than that of JN.1 in the USA, UK, and Canada, respectively (appendix p 15). These results suggest that KP.2 has higher viral fitness and potentially becomes the predominant lineage worldwide. Indeed, as of the beginning of April, 2024, the estimated variant frequency of KP.2 has already reached 20% in the UK (appendix p 15).
We then did a neutralisation assay using monovalent XBB.1.5 vaccine sera and breakthrough infection sera with XBB.1.5, EG.5, HK.3, and JN.1 infections. In all cases, the 50% neutralisation titre against KP.2 was significantly lower than that against JN.1 (appendix p 15). Altogether, these results suggest that the increased immune escape ability of KP.2 contributes to its higher Re compared with JN.1.