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Author Spotlight: A Pseudotype Virus System for Assessing Omicron Subvariants and Neutralizing Antibodies in SARS-CoV-2 Research
Published on: September 8, 2023
Emerging Omicron subvariants evade neutralizing immunity elicited by vaccine or BA.1/BA.2 infection
Zehui Chen1, Jiaming Li2, Jing Zheng1
1Xiamen Center for Disease Control and Prevention, Xiamen, China.
Abstract:
The newly emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2.75 and BA.2.76 subvariants contained 35 and 29 additional mutations in its spike (S) protein compared with the reference SARS-CoV-2 genome, respectively. Here, we measured the evasion degree of the BA.1, BA.2, BA.4, BA.5, BA.2.75, and BA.2.76 subvariants from neutralizing immunity in people previously infected with the Omicron BA.1 and BA.2, determined the effect of vaccination on immune evasion, and compared the titers of neutralizing antibodies in serums between acute infection and convalescence. Results showed that the neutralization effect of serums from patients with different vaccination statuses and BA.1/BA.2 breakthrough infection decreased with the Omicron evolution from BA.1 to BA.2, BA.4, BA.5, BA.2.75, and BA.2.76. This study also indicated that the existing vaccines could no longer provide effective protection, especially for the emerging BA.2.75 and BA.2.76 subvariants. Therefore, vaccines against emerging epidemic strains should be designed specifically. In the future, we can not only focus on the current strains, but also predict and design new vaccines against potential mutant strains. At the same time, we can combine the virus strains' infection characteristics to develop protective measures for virus colonization areas, such as nasal protection spray. Besides, further studies on the Y248N mutation of BA.2.76 subvariant were also necessary to explore its contribution to the enhanced immune evasion ability.
Insights
New Omicron subvariants like BA.2.75 and BA.2.76 show increased immune evasion. Existing vaccines offer reduced protection against these evolving SARS-CoV-2 strains, necessitating updated vaccine development.
Area of Science:
- Virology
- Immunology
- Vaccinology
Background:
- Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariants, including BA.2.75 and BA.2.76, exhibit significant mutations in their spike (S) protein.
- The continuous evolution of SARS-CoV-2 necessitates an understanding of immune evasion by new subvariants.
Purpose of the Study:
- To quantify the immune evasion capabilities of Omicron subvariants BA.1, BA.2, BA.4, BA.5, BA.2.75, and BA.2.76.
- To assess the impact of vaccination and prior infection (Omicron BA.1 and BA.2) on neutralizing antibody responses.
- To compare neutralizing antibody titers during acute infection and convalescence.
Main Methods:
- Measurement of neutralizing immunity evasion by various Omicron subvariants.
- Analysis of serum samples from individuals with different vaccination statuses and breakthrough infections.
- Comparison of neutralizing antibody titers.
Main Results:
- Neutralizing activity of sera decreased progressively with Omicron evolution from BA.1 through BA.2, BA.4, BA.5, BA.2.75, and BA.2.76.
- Existing vaccines demonstrated diminished efficacy against newer subvariants, particularly BA.2.75 and BA.2.76.
- Antibody titers varied between acute infection and convalescence periods.
Conclusions:
- Current vaccines are less effective against emerging SARS-CoV-2 Omicron subvariants like BA.2.75 and BA.2.76.
- Development of specifically designed vaccines targeting emergent strains is crucial.
- Future strategies should include predicting and designing vaccines for potential future mutants and developing localized protective measures.
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