tetano
Editor, Senior Moderator
mBio
. 2021 May 11;12(3):e00930-21.
doi: 10.1128/mBio.00930-21.
An Engineered Receptor-Binding Domain Improves the Immunogenicity of Multivalent SARS-CoV-2 Vaccines
Yan Guo[SUP] #[/SUP][SUP] 1 [/SUP], Wenhui He[SUP] #[/SUP][SUP] 1 [/SUP], Huihui Mou[SUP] #[/SUP][SUP] 1 [/SUP], Lizhou Zhang[SUP] #[/SUP][SUP] 1 [/SUP], Jing Chang[SUP] 1 [/SUP], Shoujiao Peng[SUP] 1 [/SUP], Amrita Ojha[SUP] 1 [/SUP], Rubens Tavora[SUP] 1 [/SUP], Mark S Parcells[SUP] 2 [/SUP], Guangxiang Luo[SUP] 3 [/SUP], Wenhui Li[SUP] 4 [/SUP], Guocai Zhong[SUP] 5 6 [/SUP], Hyeryun Choe[SUP] 1 [/SUP], Michael Farzan[SUP] 7 [/SUP], Brian D Quinlan[SUP] 7 [/SUP]
Affiliations
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein mediates viral entry into cells expressing angiotensin-converting enzyme 2 (ACE2). The S protein engages ACE2 through its receptor-binding domain (RBD), an independently folded 197-amino-acid fragment of the 1,273-amino-acid S-protein protomer. The RBD is the primary SARS-CoV-2 neutralizing epitope and a critical target of any SARS-CoV-2 vaccine. Here, we show that this RBD conjugated to each of two carrier proteins elicited more potent neutralizing responses in immunized rodents than did a similarly conjugated proline-stabilized S-protein ectodomain. Nonetheless, the native RBD is expressed inefficiently, limiting its usefulness as a vaccine antigen. However, we show that an RBD engineered with four novel glycosylation sites (gRBD) is expressed markedly more efficiently and generates a more potent neutralizing responses as a DNA vaccine antigen than the wild-type RBD or the full-length S protein, especially when fused to multivalent carriers, such as a Helicobacter pylori ferritin 24-mer. Further, gRBD is more immunogenic than the wild-type RBD when administered as a subunit protein vaccine. Our data suggest that multivalent gRBD antigens can reduce costs and doses, and improve the immunogenicity, of all major classes of SARS-CoV-2 vaccines.IMPORTANCE All available vaccines for coronavirus disease 2019 (COVID-19) express or deliver the full-length SARS-CoV-2 spike (S) protein. We show that this antigen is not optimal, consistent with observations that the vast majority of the neutralizing response to the virus is focused on the S-protein receptor-binding domain (RBD). However, this RBD is not expressed well as an independent domain, especially when expressed as a fusion protein with a multivalent scaffold. We therefore engineered a more highly expressed form of the SARS-CoV-2 RBD by introducing four glycosylation sites into a face of the RBD normally occluded in the full S protein. We show that this engineered protein, gRBD, is more immunogenic than the wild-type RBD or the full-length S protein in both genetic and protein-delivered vaccines.
Keywords: ACE2; COVID-19; RBD; SARS-CoV-2; ferritin; receptor-binding domain; vaccine.
. 2021 May 11;12(3):e00930-21.
doi: 10.1128/mBio.00930-21.
An Engineered Receptor-Binding Domain Improves the Immunogenicity of Multivalent SARS-CoV-2 Vaccines
Yan Guo[SUP] #[/SUP][SUP] 1 [/SUP], Wenhui He[SUP] #[/SUP][SUP] 1 [/SUP], Huihui Mou[SUP] #[/SUP][SUP] 1 [/SUP], Lizhou Zhang[SUP] #[/SUP][SUP] 1 [/SUP], Jing Chang[SUP] 1 [/SUP], Shoujiao Peng[SUP] 1 [/SUP], Amrita Ojha[SUP] 1 [/SUP], Rubens Tavora[SUP] 1 [/SUP], Mark S Parcells[SUP] 2 [/SUP], Guangxiang Luo[SUP] 3 [/SUP], Wenhui Li[SUP] 4 [/SUP], Guocai Zhong[SUP] 5 6 [/SUP], Hyeryun Choe[SUP] 1 [/SUP], Michael Farzan[SUP] 7 [/SUP], Brian D Quinlan[SUP] 7 [/SUP]
Affiliations
- PMID: 33975938
- DOI: 10.1128/mBio.00930-21
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein mediates viral entry into cells expressing angiotensin-converting enzyme 2 (ACE2). The S protein engages ACE2 through its receptor-binding domain (RBD), an independently folded 197-amino-acid fragment of the 1,273-amino-acid S-protein protomer. The RBD is the primary SARS-CoV-2 neutralizing epitope and a critical target of any SARS-CoV-2 vaccine. Here, we show that this RBD conjugated to each of two carrier proteins elicited more potent neutralizing responses in immunized rodents than did a similarly conjugated proline-stabilized S-protein ectodomain. Nonetheless, the native RBD is expressed inefficiently, limiting its usefulness as a vaccine antigen. However, we show that an RBD engineered with four novel glycosylation sites (gRBD) is expressed markedly more efficiently and generates a more potent neutralizing responses as a DNA vaccine antigen than the wild-type RBD or the full-length S protein, especially when fused to multivalent carriers, such as a Helicobacter pylori ferritin 24-mer. Further, gRBD is more immunogenic than the wild-type RBD when administered as a subunit protein vaccine. Our data suggest that multivalent gRBD antigens can reduce costs and doses, and improve the immunogenicity, of all major classes of SARS-CoV-2 vaccines.IMPORTANCE All available vaccines for coronavirus disease 2019 (COVID-19) express or deliver the full-length SARS-CoV-2 spike (S) protein. We show that this antigen is not optimal, consistent with observations that the vast majority of the neutralizing response to the virus is focused on the S-protein receptor-binding domain (RBD). However, this RBD is not expressed well as an independent domain, especially when expressed as a fusion protein with a multivalent scaffold. We therefore engineered a more highly expressed form of the SARS-CoV-2 RBD by introducing four glycosylation sites into a face of the RBD normally occluded in the full S protein. We show that this engineered protein, gRBD, is more immunogenic than the wild-type RBD or the full-length S protein in both genetic and protein-delivered vaccines.
Keywords: ACE2; COVID-19; RBD; SARS-CoV-2; ferritin; receptor-binding domain; vaccine.