PT  - JOURNAL ARTICLE
AU  - Yamasoba, Daichi
AU  - Uriu, Keiya
AU  - Plianchaisuk, Arnon
AU  - Kosugi, Yusuke
AU  - Pan, Lin
AU  - Zahradnik, Jiri
AU - The Genotype to Phenotype Japan (G2P-Japan) Consortium
AU  - Ito, Jumpei
AU  - Sato, Kei
TI  - Virological characteristics of the SARS-CoV-2 Omicron XBB.1.16 variant
AID  - 10.1101/2023.04.06.535883
DP  - 2023 Jan 01
TA  - bioRxiv
PG  - 2023.04.06.535883
4099  - http://biorxiv.org/content/early/2023/04/09/2023.04.06.535883.short
4100  - http://biorxiv.org/content/early/2023/04/09/2023.04.06.535883.full
AB  - At the end of March 2023, XBB.1.16, a SARS-CoV-2 omicron XBB subvariant, emerged and was detected in various countries. Compared to XBB.1.5, XBB.1.16 has two substitutions in the S protein: E180V is in the N-terminal domain, and T478R in the receptor-binding domain (RBD). We first show that XBB.1.16 had an effective reproductive number (Re) that was 1.27- and 1.17-fold higher than the parental XBB.1 and XBB.1.5, respectively, suggesting that XBB.1.16 will spread worldwide in the near future. In fact, the WHO classified XBB.1.16 as a variant under monitoring on March 30, 2023. Neutralization assays demonstrated the robust resistance of XBB.1.16 to breakthrough infection sera of BA.2 (18-fold versus B.1.1) and BA.5 (37-fold versus B.1.1). We then used six clinically-available monoclonal antibodies and showed that only sotrovimab exhibits antiviral activity against XBB subvariants, including XBB.1.16. Our results suggest that, similar to XBB.1 and XBB.1.5, XBB.1.16 is robustly resistant to a variety of anti-SARS-CoV-2 antibodies. Our multiscale investigations suggest that XBB.1.16 that XBB.1.16 has a greater growth advantage in the human population compared to XBB.1 and XBB.1.5, while the ability of XBB.1.16 to exhibit profound immune evasion is comparable to XBB.1 and XBB.1.5. The increased fitness of XBB.1.16 may be due to (1) different antigenicity than XBB.1.5; and/or (2) the mutations in the non-S viral protein(s) that may contribute to increased viral growth efficiency.Competing Interest StatementThe authors have declared no competing interest.