The SARS-CoV-2 XBB.1.16 variant is associated with a 1.27- and 1.17-fold higher effective reproductive number (Re) as compared to the XBB.1 and XBB.1.5 subvariants, respectively, thus indicating the ability of this novel Omicron variant to disseminate quickly.
As a result of this increased transmissibility, the World Health Organization (WHO) began monitoring XBB.1.16 on March 30, 2023, following its detection in several countries, including India. Earlier, the SARS-CoV-2 Omicron XBB subvariants with the F486P substitution in their spike (S) protein, which include XBB.1.5 and XBB.1.9, were widely circulating worldwide.
23B (XBB.1.16) is different from 22F (XBB) primarily through 3 new Spike mutations - S:E180V; S:K478R; & S:486P (acquired independently from other XBB sublineages). In addition, S:G252V is inherited from ancestral XBB.1
Premilinary studies with pseudovirus assays showed that the infectivity of XBB.1.16 was comparable to that of XBB.1 but unlike XBB.1.5, the latter of which had higher infectivity than the parental XBB.1 mutant. Note that the T478R and S: E180V substitution mutations have a significant influence on the infectivity of this viral variant. Whereas the T478R mutation increases the infectivity of XBB.1.16, the E180V substitution significantly reduced its viral infectivity.
As a result of this increased transmissibility, the World Health Organization (WHO) began monitoring XBB.1.16 on March 30, 2023, following its detection in several countries, including India. Earlier, the SARS-CoV-2 Omicron XBB subvariants with the F486P substitution in their spike (S) protein, which include XBB.1.5 and XBB.1.9, were widely circulating worldwide.
23B (XBB.1.16) is different from 22F (XBB) primarily through 3 new Spike mutations - S:E180V; S:K478R; & S:486P (acquired independently from other XBB sublineages). In addition, S:G252V is inherited from ancestral XBB.1
Premilinary studies with pseudovirus assays showed that the infectivity of XBB.1.16 was comparable to that of XBB.1 but unlike XBB.1.5, the latter of which had higher infectivity than the parental XBB.1 mutant. Note that the T478R and S: E180V substitution mutations have a significant influence on the infectivity of this viral variant. Whereas the T478R mutation increases the infectivity of XBB.1.16, the E180V substitution significantly reduced its viral infectivity.
