SARS-CoV-2 protein subunit vaccination elicits potent neutralizing antibody responses

The outbreak and spread of SARS-CoV-2 (Severe Acute Respiratory Syndrome coronavirus 2), the cause of coronavirus disease 2019 (COVID-19), is a current global health emergency and a prophylactic vaccine is needed urgently. The spike glycoprotein of SARS-CoV-2 mediates entry into host cells, and thus is a target for neutralizing antibodies and vaccine design. Here we show that adjuvanted protein immunization with SARS-CoV-2 spike trimers, stabilized in prefusion conformation, results in potent antibody responses in mice and rhesus macaques with neutralizing antibody titers orders of magnitude greater than those typically measured in serum from SARS-CoV-2 seropositive humans. Neutralizing antibody responses were observed after a single dose, with exceptionally high titers achieved after boosting. Furthermore, neutralizing antibody titers elicited by a dose-sparing regimen in mice were similar to those obtained from a high dose regimen. Taken together, these data strongly support the development of adjuvanted SARS-CoV-2 prefusion-stabilized spike protein subunit vaccines.

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Immunogenicity, safety, and efficacy of sequential immunizations with an SIV-based IDLV expressing CH505 Envs

npj Vaccines ◽

10.1038/s41541-020-00252-w ◽

2020 ◽

Vol 5 (1) ◽

Author(s):

Maria Blasi ◽

Donatella Negri ◽

Kevin O. Saunders ◽

Erich J. Baker ◽

Hannah Stadtler ◽

...

Keyword(s):

Immune Responses ◽

Neutralizing Antibodies ◽

Lentiviral Vector ◽

Rhesus Macaques ◽

Infected Individual ◽

Neutralizing Antibody ◽

Antibody Responses ◽

Safety And Efficacy ◽

Env Protein ◽

Hiv 1

AbstractA preventative HIV-1 vaccine is an essential intervention needed to halt the HIV-1 pandemic. Neutralizing antibodies protect against HIV-1 infection in animal models, and thus an approach toward a protective HIV-1 vaccine is to induce broadly cross-reactive neutralizing antibodies (bnAbs). One strategy to achieve this goal is to define envelope (Env) evolution that drives bnAb development in infection and to recreate those events by vaccination. In this study, we report the immunogenicity, safety, and efficacy in rhesus macaques of an SIV-based integrase defective lentiviral vector (IDLV) expressing sequential gp140 Env immunogens derived from the CH505 HIV-1-infected individual who made the CH103 and CH235 bnAb lineages. Immunization with IDLV expressing sequential CH505 Envs induced higher magnitude and more durable binding and neutralizing antibody responses compared to protein or DNA +/− protein immunizations using the same sequential envelopes. Compared to monkeys immunized with a vector expressing Envs alone, those immunized with the combination of IDLV expressing Env and CH505 Env protein demonstrated improved durability of antibody responses at six months after the last immunization as well as lower peak viremia and better virus control following autologous SHIV-CH505 challenge. There was no evidence of vector mobilization or recombination in the immunized and challenged monkeys. Although the tested vaccines failed to induce bnAbs and to mediate significant protection following SHIV-challenge, our results show that IDLV proved safe and successful at inducing higher titer and more durable immune responses compared to other vaccine platforms.

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Breakthrough of SIV strain smE660 challenge in SIV strain mac239-vaccinated rhesus macaques despite potent autologous neutralizing antibody responses

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1509731112 ◽

2015 ◽

Vol 112 (34) ◽

pp. 10780-10785 ◽

Cited By ~ 21

Author(s):

Samantha L. Burton ◽

Katie M. Kilgore ◽

S. Abigail Smith ◽

Sharmila Reddy ◽

Eric Hunter ◽

...

Keyword(s):

Simian Immunodeficiency Virus ◽

Neutralizing Antibodies ◽

Rhesus Macaques ◽

Neutralizing Antibody ◽

Active Immunization ◽

Antibody Responses ◽

Challenge Virus ◽

Gm Csf ◽

Immunodeficiency Virus

Although the correlates of immunological protection from human immunodeficiency virus or simian immunodeficiency virus infection remain incompletely understood, it is generally believed that medium to high titers of serum neutralizing antibodies (nAbs) against the challenge virus will prevent infection. This paradigm is based on a series of studies in which passive transfer of HIV-specific nAbs protected rhesus macaques (RMs) from subsequent mucosal challenge with a chimeric human/simian immunodeficiency virus. However, it is unknown whether nAb titers define protection in the setting of active immunization. Here we determined serum nAb titers against breakthrough transmitted/founder (T/F) SIVsmE660-derived envelope glycoprotein (Env) variants from 14 RMs immunized with SIVmac239-based DNA-prime/modified vaccinia virus Ankara-boost vaccine regimens that included GM-CSF or CD40L adjuvants and conferred significant but incomplete protection against repeated low-dose intrarectal challenge. A single Env variant established infection in all RMs except one, with no identifiable genetic signature associated with vaccination breakthrough compared with T/F Envs from four unvaccinated monkeys. Breakthrough T/F Env pseudoviruses were potently neutralized in vitro by heterologous pooled serum from chronically SIVsmE660-infected monkeys at IC50 titers exceeding 1:1,000,000. Remarkably, the T/F Env pseudoviruses from 13 of 14 monkeys were also susceptible to neutralization by autologous prechallenge serum at in vitro IC50 titers ranging from 1:742–1:10,832. These titers were similar to those observed in vaccinated RMs that remained uninfected. These data suggest that the relationship between serum nAb titers and protection from mucosal SIV challenge in the setting of active immunization is more complex than previously recognized, warranting further studies into the balance between immune activation, target cell availability, and protective antibody responses.

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Immunogenicity, safety and efficacy of sequential immunizations with an SIV-based IDLV expressing CH505 Envs

10.1101/2020.03.06.980680 ◽

2020 ◽

Author(s):

Blasi Maria ◽

Negri Donatella ◽

Saunders O Kevin ◽

Baker J Erich ◽

Stadtler Hannah ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Lentiviral Vector ◽

Rhesus Macaques ◽

Infected Individual ◽

Neutralizing Antibody ◽

Antibody Responses ◽

Safety And Efficacy ◽

Broadly Neutralizing Antibody ◽

Env Protein ◽

Hiv 1

AbstractA preventative HIV-1 vaccine is an essential intervention needed to halt the HIV-1 pandemic. Neutralizing antibodies protect against HIV-1 infection in animal models, and thus an approach toward a protective HIV-1 vaccine is to induce broadly cross-reactive neutralizing antibodies (bnAbs). One strategy to achieve this goal is to define envelope (Env) evolution that drives bnAb development in infection and to recreate those events by vaccination. In this study we report the immunogenicity, safety and efficacy in rhesus macaques of an SIV-based integrase defective lentiviral vector (IDLV) expressing sequential gp140 Env immunogens derived from the CH505 HIV-1-infected individual who made the CH103 and CH235 bnAb lineages. Immunization with IDLV expressing sequential CH505 Env induced higher magnitude and more durable binding and neutralizing antibody responses compared to protein or DNA +/- protein immunizations using the same sequential envelopes. Compared to monkeys immunized with vector expressing Envs alone, those immunized with the combination of IDLV expressing Env and CH505 Env protein demonstrated improved durability of antibody responses at six month after the last immunization as well as lower peak viremia and better virus control following autologous SHIV-CH505 challenge. There was no evidence of vector mobilization or recombination in the immunized and challenged monkeys. Our results show that while IDLV proved safe and successful at inducing higher titer and more durable immune responses compared to other vaccine platforms, the use of non-stabilized sequential envelope trimers did not induce broadly neutralizing antibody responses.

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Control of SARS-CoV-2 infection after Spike DNA or Spike DNA+Protein co-immunization in rhesus macaques

10.1101/2021.06.11.448032 ◽

2021 ◽

Author(s):

Margherita Rosati ◽

Mahesh Agarwal ◽

Xintao Hu ◽

Santhi Devasundaram ◽

Dimitris Stellas ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Protective Efficacy ◽

Rhesus Macaques ◽

Neutralizing Antibody ◽

Anatomical Site ◽

Cell Responses ◽

Cellular Immune Responses ◽

Antibody Titers ◽

Cellular Immune

The speed of development, versatility and efficacy of mRNA-based vaccines have been amply demonstrated in the case of SARS-CoV-2. DNA vaccines represent an important alternative since they induce both humoral and cellular immune responses in animal models and in human trials. We tested the immunogenicity and protective efficacy of DNA-based vaccine regimens expressing different prefusion-stabilized SARS-CoV-2 Spike antigens upon intramuscular injection followed by electroporation in rhesus macaques. Different Spike DNA vaccine regimens induced antibodies that potently neutralized SARS-CoV-2 in vitro and elicited robust T cell responses. The DNA-only vaccine regimens were compared to a regimen that included co-immunization of Spike DNA and protein in the same anatomical site, the latter of which showed significant higher antibody responses. All vaccine regimens led to control of SARS-CoV-2 intranasal/intratracheal challenge and absence of virus dissemination to the lower respiratory tract. Vaccine-induced binding and neutralizing antibody titers and antibody-dependent cellular phagocytosis inversely correlated with transient virus levels in the nasal mucosa. Importantly, the Spike DNA+Protein co-immunization regimen induced the highest binding and neutralizing antibodies and showed the strongest control against SARS-CoV-2 challenge in rhesus macaques.

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A single immunization with spike-functionalized ferritin vaccines elicits neutralizing antibody responses against SARS-CoV-2 in mice

10.1101/2020.08.28.272518 ◽

2020 ◽

Cited By ~ 2

Author(s):

Abigail E. Powell ◽

Kaiming Zhang ◽

Mrinmoy Sanyal ◽

Shaogeng Tang ◽

Payton A. Weidenbacher ◽

...

Keyword(s):

Single Dose ◽

Neutralizing Antibodies ◽

Subunit Vaccine ◽

Neutralizing Antibody ◽

Antibody Responses ◽

Receptor Binding Domain ◽

Amino Acid Deletion ◽

Vaccine Candidates ◽

Self Assembling ◽

Antibody Titers

AbstractDevelopment of a safe and effective SARS-CoV-2 vaccine is a public health priority. We designed subunit vaccine candidates using self-assembling ferritin nanoparticles displaying one of two multimerized SARS-CoV-2 spikes: full-length ectodomain (S-Fer) or a C-terminal 70 amino-acid deletion (SΔC-Fer). Ferritin is an attractive nanoparticle platform for production of vaccines and ferritin-based vaccines have been investigated in humans in two separate clinical trials. We confirmed proper folding and antigenicity of spike on the surface of ferritin by cryo-EM and binding to conformation-specific monoclonal antibodies. After a single immunization of mice with either of the two spike ferritin particles, a lentiviral SARS-CoV-2 pseudovirus assay revealed mean neutralizing antibody titers at least 2-fold greater than those in convalescent plasma from COVID-19 patients. Additionally, a single dose of SΔC-Fer elicited significantly higher neutralizing responses as compared to immunization with the spike receptor binding domain (RBD) monomer or spike ectodomain trimer alone. After a second dose, mice immunized with SΔC-Fer exhibited higher neutralizing titers than all other groups. Taken together, these results demonstrate that multivalent presentation of SARS-CoV-2 spike on ferritin can notably enhance elicitation of neutralizing antibodies, thus constituting a viable strategy for single-dose vaccination against COVID-19.

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SARS-CoV-2 binding and neutralizing antibody levels after vaccination with Ad26.COV2.S predict durable protection in rhesus macaques

10.1101/2021.01.30.428921 ◽

2021 ◽

Author(s):

Ramon Roozendaal ◽

Laura Solforosi ◽

Daniel Stieh ◽

Jan Serroyen ◽

Roel Straetemans ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Protective Efficacy ◽

Rhesus Macaques ◽

Natural Infection ◽

Neutralizing Antibody ◽

Preliminary Evidence ◽

Correlates Of Protection ◽

Antibody Titers ◽

Antibody Levels ◽

The Relationship

The first COVID-19 vaccines have recently gained authorization for emergency use.1,2 At this moment, limited knowledge on duration of immunity and efficacy of these vaccines is available. Data on other coronaviruses after natural infection suggest that immunity to SARS-CoV-2 might be short lived,3,4 and preliminary evidence indicates waning antibody titers following SARS-CoV-2 infection.5 Here we model the relationship between immunogenicity and protective efficacy of a series of Ad26 vectors encoding stabilized variants of the SARS-CoV-2 Spike (S) protein in rhesus macaques6,7,8 and validate the analyses by challenging macaques 6 months after immunization with the Ad26.COV2.S vaccine candidate that has been selected for clinical development. We find that Ad26.COV2.S confers durable protection against replication of SARS-CoV-2 in the lungs that is predicted by the levels of S-binding and neutralizing antibodies. These results suggest that Ad26.COV2.S could confer durable protection in humans and that immunological correlates of protection may enable the prediction of durability of protection.

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Sex disparities and neutralizing antibody durability to SARS-CoV-2 infection in convalescent individuals

10.1101/2021.02.01.21250493 ◽

2021 ◽

Author(s):

Alena J. Markmann ◽

Natasa Giallourou ◽

D. Ryan Bhowmik ◽

Yixuan J. Hou ◽

Aaron Lerner ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Antibody Responses ◽

Human Antibody ◽

Antibody Titers ◽

Sex Disparities ◽

Binding Antibody ◽

Male Sex ◽

Antibody Levels ◽

First Time

AbstractThe coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) has now caused over 2 million deaths worldwide and continues to expand. Currently, much is unknown about functionally neutralizing human antibody responses and durability to SARS-CoV-2. Using convalescent sera collected from 101 COVID-19 recovered individuals 21-212 days after symptom onset with forty-eight additional longitudinal samples, we measured functionality and durability of serum antibodies. We also evaluated associations between individual demographic and clinical parameters with functional neutralizing antibody responses to COVID-19. We found robust antibody durability out to six months, as well as significant positive associations with the magnitude of the neutralizing antibody response and male sex. We also show that SARS-CoV-2 convalescent neutralizing antibodies are higher in individuals with cardio-metabolic comorbidities.SignificanceIn this study we found that neutralizing antibody responses in COVID-19 convalescent individuals vary in magnitude but are durable and correlate well with RBD Ig binding antibody levels compared to other SARS-CoV-2 antigen responses. In our cohort, higher neutralizing antibody titers are independently and significantly associated with male sex compared to female sex. We also show for the first time, that higher convalescent antibody titers in male donors are associated with increased age and symptom grade. Furthermore, cardio-metabolic co-morbidities are associated with higher antibody titers independently of sex. Here, we present an in-depth evaluation of serologic, demographic, and clinical correlates of functional antibody responses and durability to SARS-CoV-2.

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Glycosylation of Immunodominant Linear Epitopes in the Carboxy-Terminal Region of the Caprine Arthritis-Encephalitis Virus Surface Envelope Enhances Vaccine-Induced Type-Specific and Cross-Reactive Neutralizing Antibody Responses

Journal of Virology ◽

10.1128/jvi.78.17.9190-9202.2004 ◽

2004 ◽

Vol 78 (17) ◽

pp. 9190-9202 ◽

Cited By ~ 7

Author(s):

J. D. Trujillo ◽

N. M. Kumpula-McWhirter ◽

K. J. Hötzel ◽

M. Gonzalez ◽

W. P. Cheevers

Keyword(s):

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Fold Increase ◽

Antibody Responses ◽

Enzyme Linked Immunosorbent Assay ◽

Wild Type ◽

Virus Surface ◽

Antibody Titers ◽

Linear Epitopes ◽

Carboxy Terminal

ABSTRACT This study evaluated type-specific and cross-reactive neutralizing antibodies induced by immunization with modified surface glycoproteins (SU) of the 63 isolate of caprine arthritis-encephalitis lentivirus (CAEV-63). Epitope mapping of sera from CAEV-infected goats localized immunodominant linear epitopes in the carboxy terminus of SU. Two modified SU (SU-M and SU-T) and wild-type CAEV-63 SU (SU-W) were produced in vaccinia virus and utilized to evaluate the effects of glycosylation or the deletion of immunodominant linear epitopes on neutralizing antibody responses induced by immunization. SU-M contained two N-linked glycosylation sites inserted into the target epitopes by R539S and E542N mutations. SU-T was truncated at 518A, upstream from the target epitopes, by introduction of termination codons at 519Y and 521Y. Six yearling Saanen goats were immunized subcutaneously with 30 μg of SU-W, SU-M, or SU-T in Quil A adjuvant and boosted at 3, 7, and 16 weeks. SU antibody titers determined by indirect enzyme-linked immunosorbent assay demonstrated anamnestic responses after each boost. Wild-type and modified SU-induced type-specific CAEV-63 neutralizing antibodies and cross-reactive neutralizing antibodies against CAEV-Co, a virus isolate closely related to CAEV-63, and CAEV-1g5, an isolate geographically distinct from CAEV-63, were determined. Immunization with SU-T resulted in altered recognition of SU linear epitopes and a 2.8- to 4.6-fold decrease in neutralizing antibody titers against CAEV-63, CAEV-Co, and CAEV-1g5 compared to titers of SU-W-immunized goats. In contrast, immunization with SU-M resulted in reduced recognition of glycosylated epitopes and a 2.4- to 2.7-fold increase in neutralizing antibody titers compared to titers of SU-W-immunized goats. Thus, the glycosylation of linear immunodominant nonneutralization epitopes, but not epitope deletion, is an effective strategy to enhance neutralizing antibody responses by immunization.

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Comparison of Human H3N2 Antibody Responses Elicited by Egg-Based, Cell-Based, and Recombinant Protein–Based Influenza Vaccines During the 2017–2018 Season

Clinical Infectious Diseases ◽

10.1093/cid/ciz996 ◽

2019 ◽

Vol 71 (6) ◽

pp. 1447-1453 ◽

Cited By ~ 1

Author(s):

Sigrid Gouma ◽

Seth J Zost ◽

Kaela Parkhouse ◽

Angela Branche ◽

David J Topham ◽

...

Keyword(s):

Recombinant Protein ◽

Neutralizing Antibody ◽

Antibody Responses ◽

Influenza Vaccines ◽

Vaccine Antigen ◽

H3n2 Virus ◽

High Dose ◽

Wild Type ◽

H1n1 Vaccine ◽

Antibody Titers

Abstract Background The H3N2 component of egg-based 2017–2018 influenza vaccines possessed an adaptive substitution that alters antigenicity. Several influenza vaccines include antigens that are produced through alternative systems, but a systematic comparison of different vaccines used during the 2017–2018 season has not been completed. Methods We compared antibody responses in humans vaccinated with Fluzone (egg-based, n = 23), Fluzone High-Dose (egg-based, n = 16), Flublok (recombinant protein–based, n = 23), or Flucelvax (cell-based, n = 23) during the 2017–2018 season. We completed neutralization assays using an egg-adapted H3N2 virus, a cell-based H3N2 virus, wild-type 3c2.A and 3c2.A2 H3N2 viruses, and the H1N1 vaccine strain. We also performed enzyme-linked immunosorbent assays using a recombinant wild-type 3c2.A hemagglutinin. Antibody responses were compared in adjusted analysis. Results Postvaccination neutralizing antibody titers to 3c2.A and 3c2.A2 were higher in Flublok recipients compared with Flucelvax or Fluzone recipients (P < .01). Postvaccination titers to 3c2.A and 3c2.A2 were similar in Flublok and Fluzone High-Dose recipients, though seroconversion rates trended higher in Flublok recipients. Postvaccination titers in Flucelvax recipients were low to all H3N2 viruses tested, including the cell-based H3N2 strain. Postvaccination neutralizing antibody titers to H1N1 were similar among the different vaccine groups. Conclusions These data suggest that influenza vaccine antigen match and dose are both important for eliciting optimal H3N2 antibody responses in humans. Future studies should be designed to determine if our findings directly impact vaccine effectiveness. Clinical Trials Registration NCT03068949.

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Redundancy and Plasticity of Neutralizing Antibody Responses Are Cornerstone Attributes of the Human Immune Response to the Smallpox Vaccine

Journal of Virology ◽

10.1128/jvi.02244-07 ◽

2008 ◽

Vol 82 (7) ◽

pp. 3751-3768 ◽

Cited By ~ 61

Author(s):

Mohammed Rafii-El-Idrissi Benhnia ◽

Megan M. McCausland ◽

Hua-Poo Su ◽

Kavita Singh ◽

Julia Hoffmann ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Safety Net ◽

Antibody Responses ◽

Smallpox Vaccine ◽

Human Antibody ◽

Neutralization Activity ◽

Antibody Titers ◽

Human Immune Response ◽

Human Immune

ABSTRACT The smallpox vaccine is widely considered the gold standard for human vaccines, yet the key antibody targets in humans remain unclear. We endeavored to identify a stereotypic, dominant, mature virion (MV) neutralizing antibody target in humans which could be used as a diagnostic serological marker of protective humoral immunity induced by the smallpox vaccine (vaccinia virus [VACV]). We have instead found that diversity is a defining characteristic of the human antibody response to the smallpox vaccine. We show that H3 is the most immunodominant VACV neutralizing antibody target, as determined by correlation analysis of immunoglobulin G (IgG) specificities to MV neutralizing antibody titers. It was determined that purified human anti-H3 IgG is sufficient for neutralization of VACV; however, depletion or blockade of anti-H3 antibodies revealed no significant reduction in neutralization activity, showing anti-H3 IgG is not required in vaccinated humans (or mice) for neutralization of MV. Comparable results were obtained for human (and mouse) anti-L1 IgG and even for anti-H3 and anti-L1 IgG in combination. In addition to H3 and L1, human antibody responses to D8, A27, D13, and A14 exhibited statistically significant correlations with virus neutralization. Altogether, these data indicate the smallpox vaccine succeeds in generating strong neutralizing antibody responses not by eliciting a stereotypic response to a single key antigen but instead by driving development of neutralizing antibodies to multiple viral proteins, resulting in a “safety net” of highly redundant neutralizing antibody responses, the specificities of which can vary from individual to individual. We propose that this is a fundamental attribute of the smallpox vaccine.

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