iScience (May 2024)

Characterizing fitness and immune escape of SARS-CoV-2 EG.5 sublineage using elderly serum and nasal organoid

  • Xiaojuan Zhang,
  • Stephanie Joy-Ann Lam,
  • Jonathan Daniel Ip,
  • Carol Ho-Yan Fong,
  • Allen Wing-Ho Chu,
  • Wan-Mui Chan,
  • Yoyo Suet-Yiu Lai,
  • Hoi-Wah Tsoi,
  • Brian Pui-Chun Chan,
  • Lin-Lei Chen,
  • Xinjie Meng,
  • Shuofeng Yuan,
  • Hanjun Zhao,
  • Vincent Chi-Chung Cheng,
  • Jacqueline Kwan Yuk Yuen,
  • Kwok-Yung Yuen,
  • Jie Zhou,
  • Kelvin Kai-Wang To

Journal volume & issue
Vol. 27, no. 5
p. 109706

Abstract

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Summary: SARS-CoV-2 Omicron variant has evolved into sublineages. Here, we compared the neutralization susceptibility and viral fitness of EG.5.1 and XBB.1.9.1. Serum neutralization antibody titer against EG.5.1 was 1.71-fold lower than that for XBB.1.9.1. However, there was no significant difference in virus replication between EG.5.1 and XBB.1.9.1 in human nasal organoids and TMPRSS2/ACE2 over-expressing A549 cells. No significant difference was observed in competitive fitness and cytokine/chemokine response between EG.5.1 and XBB.1.9.1. Both EG.5.1 and XBB.1.9.1 replicated more robustly in the nasal organoid from a younger adult than that from an older adult. Our findings suggest that enhanced immune escape contributes to the dominance of EG.5.1 over earlier sublineages. The combination of population serum susceptibility testing and viral fitness evaluation with nasal organoids may hold promise in risk assessment of upcoming variants. Utilization of serum specimens and nasal organoid derived from older adults provides a targeted risk assessment for this vulnerable population.

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