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SARS-CoV-2 B.1.617.2 Delta variant replication and immune evasion
Petra Mlcochova1,2, Steven A Kemp1,2,3, Mahesh Shanker Dhar4
1Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Cambridge, UK.
Nature
|September 6, 2021
Summary
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant shows reduced sensitivity to neutralizing antibodies and compromised vaccine effectiveness. Continued infection control measures are crucial, even after vaccination, to manage this highly transmissible variant.
Area of Science:
- Virology
- Immunology
- Epidemiology
Background:
- The B.1.617.2 (Delta) variant of SARS-CoV-2 emerged in India, outcompeting earlier strains like Alpha and Kappa.
- The Delta variant exhibits increased transmissibility and immune evasion properties compared to previous SARS-CoV-2 lineages.
Purpose of the Study:
- To evaluate the in vitro characteristics of the Delta variant, including its sensitivity to neutralizing antibodies and replication efficiency.
- To assess the effectiveness of vaccines against the Delta variant in a real-world healthcare setting.
Main Methods:
- In vitro assays using pseudotyped viruses to assess neutralization by antibodies from recovered individuals and vaccinees.
- Organoid and human airway epithelial models to compare replication efficiency between Delta and other variants.
- Analysis of vaccine effectiveness in healthcare workers infected during a period of mixed lineage circulation.
Main Results:
- The Delta variant demonstrated significantly reduced sensitivity to neutralizing antibodies from both recovered individuals and vaccinees compared to the wild-type.
- Delta exhibited higher replication efficiency in airway models and more efficient syncytium formation than other variants.
- Analysis indicated reduced effectiveness of the ChAdOx1 vaccine against the Delta variant compared to non-Delta strains.
Conclusions:
- The Delta variant's immune evasion and enhanced replication contribute to its dominance.
- Compromised vaccine efficacy against the Delta variant underscores the need for ongoing infection control measures.
- Further research is needed to understand the full implications of Delta variant infection on vaccine effectiveness and public health strategies.
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