Efficacy of ancestral receptor-binding domain, S1 and trimeric spike protein vaccines against SARS-CoV-2 variants B.1.1.7, B.1.351, and B.1.617.1

The ongoing coronavirus disease 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The current SARS-CoV-2 vaccines are based on spike (S) protein, S1 subunit, or receptor-binding domain (RBD) of prototype strain. Emergence of several novel SARS-CoV-2 variants has raised concern about potential immune escape. In this study, we performed an immunogenicity comparison of ancestral RBD, S1, and S ectodomain trimer (S-trimer) antigens and tested the efficacy of these prototype vaccines against the circulating variants, especially B.1.617 that has been linked to India's current COVID-19 surge. We found that RBD and S-trimer proteins could induce significantly higher neutralizing antibody titers than S1 protein. For the three vaccines, the neutralizing titers decreased over time, but still remained high for at least five months after immunization. Importantly, the three prototype vaccines were still effective in neutralizing the variants of concern, although B.1.351 and B.1.617.1 lineages showed varying degrees of reduction in neutralization by the immune sera. The vaccines-induced sera were shown to block receptor binding and inhibit S protein-mediated membrane fusion. In addition, the immune sera did not promote antibody-dependent enhancement (ADE) in vitro. Our work provides valuable information for development of SARS-CoV-2 subunit vaccines and also supports the continued use of ancestral RBD or S-based vaccines to fight the COVID-19 epidemic.

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A synthetic bispecific antibody capable of neutralizing SARS-CoV-2 Delta and Omicron

10.1101/2022.01.04.474803 ◽

2022 ◽

Author(s):

Tom Z Yuan ◽

Carolina Lucas ◽

Valter S Monteiro ◽

Akiko Iwasaki ◽

Marisa L Yang ◽

...

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Receptor Binding ◽

Bispecific Antibody ◽

Immune Escape ◽

Binding Domain ◽

Bispecific Antibodies ◽

Receptor Binding Domain ◽

Promising Strategy

Bispecific antibodies have emerged as a promising strategy for curtailing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immune escape. This brief report highlights RBT-0813 (also known as TB493-04), a synthetic, humanized, receptor-binding domain (RBD)-targeted bispecific antibody that retains picomolar affinity to the Spike (S) trimers of all major variants of concern and neutralizes both SARS-CoV-2 Delta and Omicron in vitro.

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LL-37 fights SARS-CoV-2: The Vitamin D-Inducible Peptide LL-37 Inhibits Binding of SARS-CoV-2 Spike Protein to its Cellular Receptor Angiotensin Converting Enzyme 2 In Vitro

10.1101/2020.12.02.408153 ◽

2020 ◽

Author(s):

Annika Roth ◽

Steffen Lütke ◽

Denise Meinberger ◽

Gabriele Hermes ◽

Gerhard Sengle ◽

...

Keyword(s):

Vitamin D ◽

Angiotensin Converting Enzyme ◽

Receptor Binding ◽

Viral Entry ◽

Binding Domain ◽

Receptor Binding Domain ◽

Converting Enzyme ◽

Cell Infection ◽

S Protein

AbstractObjectiveSevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the pathogen accountable for the coronavirus disease 2019 (COVID-19) pandemic. Viral entry via binding of the receptor binding domain (RBD) located within the S1 subunit of the SARS-CoV-2 Spike (S) protein to its target receptor angiotensin converting enzyme (ACE) 2 is a key step in cell infection. The efficient transition of the virus is linked to a unique protein called open reading frame (ORF) 8. As SARS-CoV-2 infections can develop into life-threatening lower respiratory syndromes, effective therapy options are urgently needed. Several publications propose vitamin D treatment, although its mode of action against COVID-19 is not fully elucidated. It is speculated that vitamin D’s beneficial effects are mediated by up-regulating LL-37, a well-known antimicrobial peptide with antiviral effects.MethodsRecombinantly expressed SARS-CoV-2 S protein, the extended S1 subunit (S1e), the S2 subunit (S2), the receptor binding domain (RBD), and ORF8 were used for surface plasmon resonance (SPR) studies to investigate LL-37’s ability to bind to SARS-CoV-2 proteins and to localize its binding site within the S protein. Binding competition studies were conducted to confirm an inhibitory action of LL-37 on the attachment of SARS-CoV-2 S protein to its entry receptor ACE2.ResultsWe could show that LL-37 binds to SARS-CoV-2 S protein (LL-37/SStrep KD = 410 nM, LL-37/SHis KD = 410 nM) with the same affinity, as SARS-CoV-2 binds to hACE2 (hACE2/SStrep KD = 370 nM, hACE2/SHis KD = 370 nM). The binding is not restricted to the RBD of the S protein, but rather distributed along the entire length of the protein. Interaction between LL-37 and ORF8 was detected with a KD of 290 nM. Further, inhibition of the binding of SStrep (IC50 = 740 nM), S1e (IC50 = 170 nM), and RBD (IC50 = 130 nM) to hACE2 by LL-37 was demonstrated.ConclusionsWe have revealed a biochemical link between vitamin D, LL-37, and COVID-19 severity. SPR analysis demonstrated that LL-37 binds to SARS-CoV-2 S protein and inhibits binding to its receptor hACE2, and most likely viral entry into the cell. This study supports the prophylactic use of vitamin D to induce LL-37 that protects from SARS-CoV-2 infection, and the therapeutic administration of vitamin D for the treatment of COVID-19 patients. Further, our results provide evidence that the direct use of LL-37 by inhalation and systemic application may reduce the severity of COVID-19.

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High titers of multiple antibody isotypes against the SARS-CoV-2 spike receptor-binding domain and nucleoprotein associate with better neutralization

10.1101/2020.08.15.252353 ◽

2020 ◽

Author(s):

Maria G. Noval ◽

Maria E. Kaczmarek ◽

Akiko Koide ◽

Bruno A. Rodriguez-Rodriguez ◽

Ping Louie ◽

...

Keyword(s):

Antibody Response ◽

Receptor Binding ◽

Healthcare Workers ◽

Neutralizing Antibody ◽

Binding Domain ◽

Pseudotyped Virus ◽

Receptor Binding Domain ◽

Neutralization Capacity ◽

Antibody Isotypes ◽

Antibody Titers

AbstractUnderstanding antibody responses to SARS-CoV-2 is indispensable for the development of containment measures to overcome the current COVID-19 pandemic. Here, we determine the ability of sera from 101 recovered healthcare workers to neutralize both authentic SARS-CoV-2 and SARS-CoV-2 pseudotyped virus and address their antibody titers against SARS-CoV-2 nucleoprotein and spike receptor-binding domain. Interestingly, the majority of individuals have low neutralization capacity and only 6% of the healthcare workers showed high neutralizing titers against both authentic SARS-CoV-2 virus and the pseudotyped virus. We found the antibody response to SARS-CoV-2 infection generates antigen-specific isotypes as well as a diverse combination of antibody isotypes, with high titers of IgG, IgM and IgA against both antigens correlating with neutralization capacity. Importantly, we found that neutralization correlated with antibody titers as quantified by ELISA. This suggests that an ELISA assay can be used to determine seroneutralization potential. Altogether, our work provides a snapshot of the SARS-CoV-2 neutralizing antibody response in recovered healthcare workers and provides evidence that possessing multiple antibody isotypes may play an important role in SARS-CoV-2 neutralization.

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Predicting the Efficacy of COVID-19 Convalescent Plasma Donor Units with the Lumit Dx anti-Receptor Binding Domain Assay

10.1101/2021.03.08.21253135 ◽

2021 ◽

Author(s):

Sanath Kumar Janaka ◽

Natasha M Clark ◽

David T Evans ◽

Joseph P Connor

Keyword(s):

Receptor Binding ◽

Therapeutic Option ◽

Passive Immunization ◽

Binding Domain ◽

Receptor Binding Domain ◽

S Protein ◽

Antibody Assays ◽

Antibody Titers ◽

Novel Coronavirus ◽

Design And Methods

AbstractBackgroundThe novel coronavirus SARS-CoV2 that causes COVID-19 has resulted in the death of more than 2.5 million people, but no cure exists. Although passive immunization with COVID-19 convalescent plasma (CCP) provides a safe and viable therapeutic option, the selection of optimal units for therapy in a timely fashion remains a barrier.Study design and methodsSince virus neutralization is a necessary characteristic of plasma that can benefit recipients, the neutralizing titers of plasma samples were measured using a retroviral-pseudotype assay. Binding antibody titers to the spike (S) protein were also determined by a clinically available serological assay (Ortho-Vitros total IG), and an in-house ELISA. The results of these assays were compared to a measurement of antibodies directed to the receptor binding domain (RBD) of the SARS-CoV2 S protein (Promega Lumit Dx).ResultsAll measures of antibodies were highly variable, but correlated, to different degrees, with each other. However, the anti-RBD antibodies correlated with viral neutralizing titers to a greater extent than the other antibody assays.DiscussionOur observations support the use of an anti-RBD assay such as the Lumit Dx assay, as an optimal predictor of the neutralization capability of CCP.

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Twelve-month specific IgG response to SARS-CoV-2 receptor-binding domain among COVID-19 convalescent plasma donors in Wuhan

Nature Communications ◽

10.1038/s41467-021-24230-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Cesheng Li ◽

Ding Yu ◽

Xiao Wu ◽

Hong Liang ◽

Zhijun Zhou ◽

...

Keyword(s):

Receptor Binding ◽

Neutralizing Antibody ◽

Binding Domain ◽

Immune Memory ◽

Strong Positive Correlation ◽

Receptor Binding Domain ◽

Igg Antibody ◽

Humoral Immune ◽

Positive Rate ◽

Antibody Titers

AbstractTo investigate the duration of humoral immune response in convalescent coronavirus disease 2019 (COVID-19) patients, we conduct a 12-month longitudinal study through collecting a total of 1,782 plasma samples from 869 convalescent plasma donors in Wuhan, China and test specific antibody responses. The results show that positive rate of IgG antibody against receptor-binding domain of spike protein (RBD-IgG) to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the COVID-19 convalescent plasma donors exceeded 70% for 12 months post diagnosis. The level of RBD-IgG decreases with time, with the titer stabilizing at 64.3% of the initial level by the 9th month. Moreover, male plasma donors produce more RBD-IgG than female, and age of the patients positively correlates with the RBD-IgG titer. A strong positive correlation between RBD-IgG and neutralizing antibody titers is also identified. These results facilitate our understanding of SARS-CoV-2-induced immune memory to promote vaccine and therapy development.

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Efficacy and breadth of adjuvanted SARS-CoV-2 receptor-binding domain nanoparticle vaccine in macaques

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2106433118 ◽

2021 ◽

Vol 118 (38) ◽

pp. e2106433118

Author(s):

Hannah A. D. King ◽

M. Gordon Joyce ◽

Ines Lakhal-Naouar ◽

Aslaa Ahmed ◽

Camila Macedo Cincotta ◽

...

Keyword(s):

Receptor Binding ◽

Vaccine Development ◽

Neutralizing Antibody ◽

Binding Domain ◽

High Dose ◽

Receptor Binding Domain ◽

Rapid Control ◽

Novel Variants ◽

Antibody Titers ◽

Respiratory Challenge

Emergence of novel variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) underscores the need for next-generation vaccines able to elicit broad and durable immunity. Here we report the evaluation of a ferritin nanoparticle vaccine displaying the receptor-binding domain of the SARS-CoV-2 spike protein (RFN) adjuvanted with Army Liposomal Formulation QS-21 (ALFQ). RFN vaccination of macaques using a two-dose regimen resulted in robust, predominantly Th1 CD4+ T cell responses and reciprocal peak mean serum neutralizing antibody titers of 14,000 to 21,000. Rapid control of viral replication was achieved in the upper and lower airways of animals after high-dose SARS-CoV-2 respiratory challenge, with undetectable replication within 4 d in seven of eight animals receiving 50 µg of RFN. Cross-neutralization activity against SARS-CoV-2 variant B.1.351 decreased only approximately twofold relative to WA1/2020. In addition, neutralizing, effector antibody and cellular responses targeted the heterotypic SARS-CoV-1, highlighting the broad immunogenicity of RFN-ALFQ for SARS-CoV−like Sarbecovirus vaccine development.

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Differential serological and neutralizing antibody dynamics after an infection by a single SARS-CoV-2 strain

10.21203/rs.3.rs-77625/v1 ◽

2020 ◽

Author(s):

Emmanuelle Billon-Denis ◽

Audrey Ferrier-Rembert ◽

Annabelle Garnier ◽

Laurence Cheutin ◽

Clarisse Vigne ◽

...

Keyword(s):

Immune Response ◽

Receptor Binding ◽

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Binding Domain ◽

Clinical Severity ◽

Individual Factors ◽

Receptor Binding Domain ◽

Antibody Titers ◽

Antibody Dynamics

Abstract BackgroundWe report here the case of two coworkers infected by the same SARS-CoV-2 strain, presenting two different immunological outcomes. CaseOne patient presented a strong IgG anti-receptor-binding domain immune response correlated with a low and rapidly decreasing titer of neutralizing antibodies. The other patient had similar strong IgG anti-receptor-binding domain immune response but high neutralizing antibody titers. Discussion and ConclusionThus, host individual factors may be the main drivers of the immune response varying with age and clinical severity.

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Receptor-Binding Domain Proteins of SARS-CoV-2 Variants Elicited Robust Antibody Responses Cross-Reacting with Wild-Type and Mutant Viruses in Mice

Vaccines ◽

10.3390/vaccines9121383 ◽

2021 ◽

Vol 9 (12) ◽

pp. 1383

Author(s):

Juan Shi ◽

Xiaoxiao Jin ◽

Yan Ding ◽

Xiaotao Liu ◽

Anran Shen ◽

...

Keyword(s):

Receptor Binding ◽

Neutralizing Antibodies ◽

Polyclonal Antibodies ◽

Neutralizing Antibody ◽

Binding Domain ◽

Receptor Binding Domain ◽

Wild Type ◽

Neutralization Capacity ◽

Antibody Titers ◽

High Level

Multiple variants of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have spread around the world, but the neutralizing effects of antibodies induced by the existing vaccines have declined, which highlights the importance of developing vaccines against mutant virus strains. In this study, nine receptor-binding domain (RBD) proteins of the SARS-CoV-2 variants (B.1.1.7, B.1.351 and P.1 lineages) were constructed and fused with the Fc fragment of human IgG (RBD-Fc). These RBD-Fc proteins contained single or multiple amino acid substitutions at prevalent mutation points of spike protein, which enabled them to bind strongly to the polyclonal antibodies specific for wild-type RBD and to the recombinant human ACE2 protein. In the BALB/c, mice were immunized with the wild-type RBD-Fc protein first and boosted twice with the indicated mutant RBD-Fc proteins later. All mutant RBD-Fc proteins elicited high-level IgG antibodies and cross-neutralizing antibodies. The RBD-Fc proteins with multiple substitutions tended to induce higher antibody titers and neutralizing-antibody titers than the single-mutant RBD-Fc proteins. Meanwhile, both wild-type RBD-Fc protein and mutant RBD-Fc proteins induced significantly decreased neutralization capacity to the pseudovirus of B.1.351 and P.1 lineages than to the wild-type one. These data will facilitate the design and development of RBD-based subunit vaccines against SARS-COV-2 and its variants.

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Attenuated Influenza Virions Expressing the SARS-CoV-2 Receptor-Binding Domain Induce Neutralizing Antibodies in Mice

Viruses ◽

10.3390/v12090987 ◽

2020 ◽

Vol 12 (9) ◽

pp. 987 ◽

Cited By ~ 2

Author(s):

Andrea N. Loes ◽

Lauren E. Gentles ◽

Allison J. Greaney ◽

Katharine H. D. Crawford ◽

Jesse D. Bloom

Keyword(s):

Influenza Virus ◽

Receptor Binding ◽

Neutralizing Antibodies ◽

Reverse Genetics ◽

Natural Infection ◽

Neutralizing Antibody ◽

Binding Domain ◽

Effective Vaccine ◽

Receptor Binding Domain ◽

Antibody Titers

An effective vaccine is essential for controlling the spread of the SARS-CoV-2 virus. Here, we describe an influenza virus-based vaccine for SARS-CoV-2. We incorporated a membrane-anchored form of the SARS-CoV-2 spike receptor binding domain (RBD) in place of the neuraminidase (NA) coding sequence in an influenza virus also possessing a mutation that reduces the affinity of hemagglutinin for its sialic acid receptor. The resulting ΔNA(RBD)-Flu virus can be generated by reverse genetics and grown to high titers in cell culture. A single-dose intranasal inoculation of mice with ΔNA(RBD)-Flu elicits serum neutralizing antibody titers against SAR-CoV-2 comparable to those observed in humans following natural infection (~1:200). Furthermore, ΔNA(RBD)-Flu itself causes no apparent disease in mice. It might be possible to produce a vaccine similar to ΔNA(RBD)-Flu at scale by leveraging existing platforms for the production of influenza vaccines.

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Quantatitive Analysis of Conserved Sites on the SARS-CoV-2 Receptor-Binding Domain to Promote Development of Universal SARS-Like Coronavirus Vaccines

10.1101/2021.04.10.439161 ◽

2021 ◽

Author(s):

Siling Wang ◽

Dinghui Wu ◽

Hualong Xiong ◽

Juan Wang ◽

Zimin Tang ◽

...

Keyword(s):

Antibody Response ◽

Protein Binding ◽

Receptor Binding ◽

Neutralizing Antibody ◽

Binding Domain ◽

Receptor Binding Domain ◽

Pandemic Preparedness ◽

S Protein ◽

Antigenic Sites ◽

The Future

SummaryAlthough vaccines have been successfully developed and approved against SARS-CoV-2, it is still valuable to perform studies on conserved antigenic sites for preventing possible pandemic-risk of other SARS-like coronavirus in the future and prevalent SARS-CoV-2 variants. By antibodies obtained from convalescent COVID-19 individuals, receptor binding domain (RBD) were identified as immunodominant neutralizing domain that efficiently elicits neutralizing antibody response with on-going affinity mature. Moreover, we succeeded to define a quantitative antigenic map of neutralizing sites within SARS-CoV-2 RBD, and found that sites S2, S3 and S4 (new-found site) are conserved sites and determined as subimmunodominant sites, putatively due to their less accessibility than SARS-CoV-2 unique sites. P10-6G3, P07-4D10 and P05-6H7, respectively targeting S2, S3 and S4, are relatively rare antibodies that also potently neutralizes SARS-CoV, and the last mAbs performing neutralization without blocking S protein binding to receptor. Further, we have tried to design some RBDs to improve the immunogenicity of conserved sites. Our studies, focusing on conserved antigenic sites of SARS-CoV-2 and SARS-CoV, provide insights for promoting development of universal SARS-like coronavirus vaccines therefore enhancing our pandemic preparedness.

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