Citation

  • Authors: He WT. et al.
  • Year: 2022
  • Journal: Sci Transl Med 14 eabl9605
  • Applications: in vitro / DNA / FectoPRO
  • Cell type: Expi293F
    Description: Human embryonic kidney Fibroblast
    Known as: Expi 293-F, Expi, HEK-293 Expi

Method

To express antibodies, the corresponding HC and LC plasmids were transiently transfected into the Expi293 cell (Life Technologies) at 3 x 106 cells/mL with FectoPRO PolyPlus transfection reagent (Polyplus Cat # 116-040). To boost the protein yield, we fed cells with 300 mM sodium valproic acid solution and glucose solution 1 day post transfection. To purify monoclonal antibodies, the supernatants were harvested 4 days post transfection.

Abstract

To prepare for future coronavirus (CoV) pandemics, it is desirable to generate vaccines capable of eliciting broadly neutralizing antibody responses to CoVs. Here, we show that immunization of macaques with SARS-CoV-2 spike (S) protein with a two-shot protocol generated potent serum receptor binding domain cross-neutralizing antibody responses to both SARS-CoV-2 and SARS-CoV-1. Furthermore, responses were equally effective against most SARS-CoV-2 variants of concern (VOCs) and some were highly effective against Omicron. This result contrasts with human infection or many two-shot vaccination protocols where responses were typically more SARS-CoV-2 specific and where VOCs were less well neutralized. Structural studies showed that cloned macaque neutralizing antibodies, particularly using a given heavy chain germline gene, recognized a relatively conserved region proximal to the angiotensin converting enzyme 2 receptor binding site (RBS), whereas many frequently elicited human neutralizing antibodies targeted more variable epitopes overlapping the RBS. B cell repertoire differences between humans and macaques appeared to influence the vaccine response. The macaque neutralizing antibodies identified a pan-SARS-related virus epitope region less well targeted by human antibodies that could be exploited in rational vaccine design.

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