scholarly journals Yeast-produced RBD-based recombinant protein vaccines elicit broadly neutralizing antibodies and durable protective immunity against SARS-CoV-2 infection

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Jinkai Zang ◽  
Yuanfei Zhu ◽  
Yu Zhou ◽  
Chenjian Gu ◽  
Yufang Yi ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Vaccine Dose ◽  
Cost Effective ◽  
Prototype Strain ◽  
Broadly Neutralizing Antibodies ◽  
Preclinical Development ◽  
Virus Challenge ◽  
Opening Up

AbstractMassive production of efficacious SARS-CoV-2 vaccines is essential for controlling the ongoing COVID-19 pandemic. We report here the preclinical development of yeast-produced receptor-binding domain (RBD)-based recombinant protein SARS-CoV-2 vaccines. We found that monomeric RBD of SARS-CoV-2 could be efficiently produced as a secreted protein from transformed Pichia pastoris (P. pastoris) yeast. Yeast-derived RBD-monomer possessed functional conformation and was able to elicit protective level of neutralizing antibodies in mice. We further designed and expressed a genetically linked dimeric RBD protein in yeast. The engineered dimeric RBD was more potent than the monomeric RBD in inducing long-lasting neutralizing antibodies. Mice immunized with either monomeric RBD or dimeric RBD were effectively protected from live SARS-CoV-2 virus challenge even at 18 weeks after the last vaccine dose. Importantly, we found that the antisera raised against the RBD of a single SARS-CoV-2 prototype strain could effectively neutralize the two predominant circulating variants B.1.1.7 and B.1.351, implying broad-spectrum protective potential of the RBD-based vaccines. Our data demonstrate that yeast-derived RBD-based recombinant SARS-CoV-2 vaccines are feasible and efficacious, opening up a new avenue for rapid and cost-effective production of SARS-CoV-2 vaccines to achieve global immunization.

scholarly journals Elicitation of Broadly Neutralizing Antibodies against B.1.1.7, B.1.351, and B.1.617.1 SARS-CoV-2 Variants by Three Prototype Strain-Derived Recombinant Protein Vaccines

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1421
Author(s):  
Yong Yang ◽  
Jinkai Zang ◽  
Shiqi Xu ◽  
Xueyang Zhang ◽  
Sule Yuan ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Neutralizing Antibodies ◽  
Wild Type Strain ◽  
Immune Escape ◽  
High Titer ◽  
Prototype Strain ◽  
Vaccine Antigen ◽  
Broadly Neutralizing Antibodies ◽  
Continued Use ◽  
Further Development

The ongoing coronavirus disease 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Most of the currently approved SARS-CoV-2 vaccines use the prototype strain-derived spike (S) protein or its receptor-binding domain (RBD) as the vaccine antigen. The emergence of several novel SARS-CoV-2 variants has raised concerns about potential immune escape. In this study, we performed an immunogenicity comparison of prototype strain-derived RBD, S1, and S ectodomain trimer (S-trimer) antigens and evaluated their induction of neutralizing antibodies against three circulating SARS-CoV-2 variants, including B.1.1.7, B.1.351, and B.1.617.1. We found that, at the same antigen dose, the RBD and S-trimer vaccines were more potent than the S1 vaccine in eliciting long-lasting, high-titer broadly neutralizing antibodies in mice. The RBD immune sera remained highly effective against the B.1.1.7, B.1.351, and B.1.617.1 variants despite the corresponding neutralizing titers decreasing by 1.2-, 2.8-, and 3.5-fold relative to that against the wild-type strain. Significantly, the S-trimer immune sera exhibited comparable neutralization potency (less than twofold variation in neutralizing GMTs) towards the prototype strain and all three variants tested. These findings provide valuable information for further development of recombinant protein-based SARS-CoV-2 vaccines and support the continued use of currently approved SARS-CoV-2 vaccines in the regions/countries where variant viruses circulate.

scholarly journals Intranasal vaccination with a recombinant protein CTA1-DD-RBF protects mice against hRSV infection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hai Li ◽  
Hu Ren ◽  
Yan Zhang ◽  
Lei Cao ◽  
Wenbo Xu
Keyword(s):  
Recombinant Protein ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Vaccine Candidate ◽  
Human Infection ◽  
Mucosal Vaccine ◽  
Health Concern ◽  
Intranasal Immunization ◽  
Cell Immunity ◽  
Syncytial Virus

AbstractHuman respiratory syncytial virus (hRSV) infection is a major pediatric health concern worldwide. Despite more than half a century of efforts, there is still no commercially available vaccine. In this study, we constructed and purified the recombinant protein CTA1-DD-RBF composed of a CTA1-DD mucosal adjuvant and prefusion F protein (RBF) using Escherichia coli BL21 cells. We studied the immunogenicity of CTA1-DD-RBF in mice. Intranasal immunization with CTA1-DD-RBF stimulated hRSV F-specific IgG1, IgG2a, sIgA, and neutralizing antibodies as well as T cell immunity without inducing lung immunopathology upon hRSV challenge. Moreover, the protective immunity of CTA1-DD-RBF was superior to that of the RBF protein, as confirmed by the assessment of serum-neutralizing activity and viral clearance after challenge. Compared to formalin-inactivated hRSV (FI-RSV), intranasal immunization with CTA1-DD-RBF induced a Th1 immune response. In summary, intranasal immunization with CTA1-DD-RBF is safe and effective in mice. Therefore, CTA1-DD-RBF represents a potential mucosal vaccine candidate for the prevention of human infection with hRSV.

scholarly journals Single-shot rAAV5-based Vaccine Provides Long-term Protective Immunity against SARS-CoV-2 and Its Variants

2021 ◽  
Author(s):  
Guochao Liao ◽  
Xingxing Fan ◽  
Hungyan Lau ◽  
Zhongqiu Liu ◽  
Chinyu Li ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Challenge Test ◽  
Single Shot ◽  
Strong Immune Response ◽  
Virus Challenge ◽  
Limited Effectiveness ◽  
One Year

SummaryThe COVID-19 pandemic and the SARS-CoV-2 with its variants have posed unprecedented challenges worldwide. Existing vaccines have limited effectiveness against the SARS-CoV-2 variants. Therefore, novel vaccines to match current mutated viral lineages with long-term protective immunity are urgently in demand. In the current study, we for the first time designed a recombinant Adeno-Associated Virus 5 (rAAV5)-based vaccine named as rAAV-COVID-19 vaccine (Covacinplus) by using RBD-plus of spike protein with both the single-stranded and the self-complementary AAV5 delivering vectors (ssAAV5 and scAAAV5), which provides excellent protection from SARS-CoV-2 infection. A single dose vaccination induced the strong immune response against SARS-CoV-2. The induced neutralizing antibodies (NAs) titers were maintained at a high peak level of over 1:1024 even after more than one year of injection and accompanied with functional T-cells responses in mice. Importantly, both ssAAV- and scAAV-based RBD-plus vaccines exhibited high levels of serum NAs against current circulating variants including variants Alpha, Beta, Gamma and Delta. SARS-CoV-2 virus challenge test showed that ssAAV5-RBD-plus vaccine protected both young and old age mice from SARS-CoV-2 infection in the upper and the lower respiratory tracts. Moreover, whole genome sequencing demonstrated that AAV vector DNA sequences were not found in the genome of the vaccinated mice after one year vaccination, demonstrating excellent safety of the vaccine. Taken together, this study suggests that rAAV5-based vaccine is powerful against SARS-CoV-2 and its variants with long-term protective immunity and excellent safety, which has great potential for development into prophylactic vaccination in human to end this global pandemic.

scholarly journals AIDS Vaccine Research Subcommittee (AVRS) Consultation: Early-Life Immunization Strategies against HIV Acquisition

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Anjali Singh ◽  
Sallie Permar ◽  
Tobias R. Kollmann ◽  
Ofer Levy ◽  
Mary Marovich ◽  
...  
Keyword(s):  
Early Life ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Sexual Debut ◽  
Risk Groups ◽  
Hiv Vaccine ◽  
Broadly Neutralizing Antibodies ◽  
Hiv Vaccines ◽  
Vaccine Candidates ◽  
Hiv Acquisition

ABSTRACT This report summarizes a consultation meeting convened by the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), on 12 September 2017 to discuss the scientific rationale for selectively testing relevant HIV vaccine candidates in early life that are designed to initiate immune responses for lifelong protective immunity. The urgent need to develop interventions providing durable protective immunity to HIV before sexual debut coupled with the practicality of infant vaccine schedules supports optimizing infant HIV vaccines as a high priority. The panelists discussed the unique opportunities and challenges of testing candidate HIV vaccines in the context of distinct early-life immunity. Key developments providing rationale and grounds for cautious optimism regarding evaluation of early-life HIV vaccines include recent studies of early-life immune ontogeny, studies of HIV-infected infants demonstrating relatively rapid generation of broadly neutralizing antibodies (bNAbs), discovery of novel adjuvants active in early life, and cutting-edge sample-sparing systems biology and immunologic assays promising deep insight into vaccine action in infants. Multidisciplinary efforts toward the goal of an infant HIV vaccine are under way and should be nurtured and amplified. IMPORTANCE Young adults represent one of the highest-risk groups for new HIV infections and the only group in which morbidity continues to increase. Therefore, an HIV vaccine to prevent HIV acquisition in adolescence is a top priority. The introduction of any vaccine during adolescence is challenging. This meeting discussed the opportunities and challenges of testing HIV vaccine candidates in the context of the infant immune system given recent advances in our knowledge of immune ontogeny and adjuvant design and studies demonstrating that HIV-infected infants generate broadly neutralizing antibodies, a main target of HIV vaccines, more rapidly than adults. Considering the global success of pediatric vaccines, the concept of an HIV vaccine introduced in early life holds merit and warrants testing.

scholarly journals Differential Antigen Requirements for Protection against Systemic and Intranasal Vaccinia Virus Challenges in Mice

2008 ◽  
Vol 82 (14) ◽  
pp. 6829-6837 ◽  
Author(s):  
David R. Kaufman ◽  
Jaap Goudsmit ◽  
Lennart Holterman ◽  
Bonnie A. Ewald ◽  
Matthew Denholtz ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Recombinant Adenovirus ◽  
Protective Efficacy ◽  
Postexposure Prophylaxis ◽  
Virus Challenge ◽  
Protective Antigens ◽  
A Subunit ◽  
Potential Strategy

ABSTRACT The development of a subunit vaccine for smallpox represents a potential strategy to avoid the safety concerns associated with replication-competent vaccinia virus. Preclinical studies to date with subunit smallpox vaccine candidates, however, have been limited by incomplete information regarding protective antigens and the requirement for multiple boost immunizations to afford protective immunity. Here we explore the protective efficacy of replication-incompetent, recombinant adenovirus serotype 35 (rAd35) vectors expressing the vaccinia virus intracellular mature virion (IMV) antigens A27L and L1R and extracellular enveloped virion (EEV) antigens A33R and B5R in a murine vaccinia virus challenge model. A single immunization with the rAd35-L1R vector effectively protected mice against a lethal systemic vaccinia virus challenge. The rAd35-L1R vector also proved more efficacious than the combination of four rAd35 vectors expressing A27L, L1R, A33R, and B5R. Moreover, serum containing L1R-specific neutralizing antibodies afforded postexposure prophylaxis after systemic vaccinia virus infection. In contrast, the combination of rAd35-L1R and rAd35-B5R vectors was required to protect mice against a lethal intranasal vaccinia virus challenge, suggesting that both IMV- and EEV-specific immune responses are important following intranasal infection. Taken together, these data demonstrate that different protective antigens are required based on the route of vaccinia virus challenge. These studies also suggest that rAd vectors warrant further assessment as candidate subunit smallpox vaccines.

scholarly journals Non-structural proteins of dengue 2 virus offer limited protection to interferon-deficient mice after dengue 2 virus challenge

2006 ◽  
Vol 87 (2) ◽  
pp. 339-346 ◽  
Author(s):  
Amanda E. Calvert ◽  
Claire Y.-H. Huang ◽  
Richard M. Kinney ◽  
John T. Roehrig
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Structural Proteins ◽  
Wild Type ◽  
Survival Times ◽  
E Proteins ◽  
Virus Challenge ◽  
E Protein ◽  
Low Levels ◽  
Deficient Mice

Chimeric (D2/WN) viruses containing the pre-membrane (prM) and envelope (E) proteins of West Nile virus (WN virus) and the capsid (C) and non-structural proteins of dengue 2 (DEN2) virus were used to evaluate the protective immunity elicited by either the flaviviral E protein or non-structural proteins. AG129 interferon-deficient mice, previously shown to be protected against lethal DEN1 or DEN2 viral infection after vaccination with a wild-type or candidate vaccine strain of DEN1 or DEN2 virus, respectively, were immunized with chimeric D2/WN virus and then challenged with DEN2 virus. D2/WN chimeric viruses were non-pathogenic in AG129 mice. These viruses elicited little anti-DEN E antibody, high levels of anti-DEN NS1 antibody and no or very low levels of DEN2 virus-neutralizing antibodies. Only 15 % of D2/WN-immunized mice survived challenge with DEN2 virus. However, their mean survival time increased by 11–14 days over non-immunized controls. These results suggest that, whilst the non-structural proteins were able to enhance mean survival times of AG129 mice, this protection was not as effective as protection mediated by the E protein.

scholarly journals 163. Enhancing the Immunogenicity of a Novel, Low-cost Ebola Vaccine

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S211-S211
Author(s):  
Samuel D Stampfer ◽  
Rui Jin ◽  
Chinglai Yang
Keyword(s):  
Dna Vaccine ◽  
Disulfide Bonds ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Cost Effective ◽  
Hemorrhagic Fever ◽  
Wild Type ◽  
Mammalian Expression ◽  
Antibody Titers

Abstract Background Ebolaviruses cause viral hemorrhagic fever with high mortality rates. Nearly all Ebola vaccines in development use Ebola glycoprotein (GP) as the immunizing antigen. GP is present on the viral membrane and functions in cell entry by binding the cellular receptor and mediating membrane fusion; antibodies to GP induce protective immunity. Ebola also produces sGP: a smaller, secreted form of GP containing the receptor-binding domain; it is also able to induce protective immunity. sGP naturally refolds after thermal denaturation and thus may be more stable than GP, and may also be more cost effective as it is produced easily in high quantities. sGP is a homodimer that is covalently linked by a cysteine near its C-terminus. In this work, we explored how modifications to sGP that affect its ability to dimerize also alter its immunogenicity. Methods sGP mutants were generated in the pCAGGS mammalian expression plasmid, and injected into mice as a DNA vaccine. Mouse sera was tested by ELISA against sGP and GP proteins, and in a neutralization assay against GP-typed pseudovirions. Results We generated 4 different mutants of sGP that had altered abilities to form inter-protomer disulfide bonds. All had a mutated or deleted cysteine at position 306; two had disulfide-bonding restored by introduction of an engineered inter-protomer disulfide bond. Mice were immunized with a DNA vaccine encoding either an sGP mutant or wild-type sGP, and sera were collected. We found that sera from sGP mutants with reduced interprotomer disulfide bonds had significantly higher antibody titers to sGP and GP than sera from our wild-type sGP and engineered-disulfide sGP immunized mice. Antibody titers were similar between sGP and GP; these titers correlated with neutralization ability. Relative binding to sGP & GP (by ELISA OD) & relative % neutralization of pseudovirions at 1:10 dilution Conclusion Immunogenicity of Ebola sGP was enhanced significantly when mutations were introduced to reduce its ability to covalently dimerize. Immunogenicity correlated with induction of neutralizing antibodies, implying that our mutants may outperform wild-type sGP when used as a vaccine in vivo. This work helps paves the way for an alternative Ebola vaccine that has the potential to be more cost-effective and heat-stable than the currently-licensed vaccine. Disclosures Samuel D. Stampfer, MD/PhD, Gilead (Shareholder)

scholarly journals Panels of HIV-1 Subtype C Env Reference Strains for Standardized Neutralization Assessments

2017 ◽  
Vol 91 (19) ◽  
Author(s):  
Peter Hraber ◽  
Cecilia Rademeyer ◽  
Carolyn Williamson ◽  
Michael S. Seaman ◽  
Raphael Gottardo ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Natural Infection ◽  
A Priori ◽  
Cost Effective ◽  
Subtype C ◽  
Broadly Neutralizing Antibodies ◽  
Neutralization Activity ◽  
Clade C ◽  
Immunological Assays ◽  
Hiv 1

ABSTRACT In the search for effective immunologic interventions to prevent and treat HIV-1 infection, standardized reference reagents are a cost-effective way to maintain robustness and reproducibility among immunological assays. To support planned and ongoing studies where clade C predominates, here we describe three virus panels, chosen from 200 well-characterized clade C envelope (Env)-pseudotyped viruses from early infection. All 200 Envs were expressed as a single round of replication pseudoviruses and were tested to quantify neutralization titers by 16 broadly neutralizing antibodies (bnAbs) and sera from 30 subjects with chronic clade C infections. We selected large panels of 50 and 100 Envs either to characterize cross-reactive breadth for sera identified as having potent neutralization activity based on initial screening or to evaluate neutralization magnitude-breadth distributions of newly isolated antibodies. We identified these panels by downselection after hierarchical clustering of bnAb neutralization titers. The resulting panels represent the diversity of neutralization profiles throughout the range of virus sensitivities identified in the original panel of 200 viruses. A small 12-Env panel was chosen to screen sera from vaccine trials or natural-infection studies for neutralization responses. We considered panels selected by previously described methods but favored a computationally informed method that enabled selection of viruses representing diverse neutralization sensitivity patterns, given that we do not a priori know what the neutralization-response profile of vaccine sera will be relative to that of sera from infected individuals. The resulting 12-Env panel complements existing panels. Use of standardized panels enables direct comparisons of data from different trials and study sites testing HIV-1 clade C-specific products. IMPORTANCE HIV-1 group M includes nine clades and many recombinants. Clade C is the most common lineage, responsible for roughly half of current HIV-1 infections, and is a focus for vaccine design and testing. Standard reference reagents, particularly virus panels to study neutralization by antibodies, are crucial for developing cost-effective and yet rigorous and reproducible assays against diverse examples of this variable virus. We developed clade C-specific panels for use as standardized reagents to monitor complex polyclonal sera for neutralization activity and to characterize the potency and breadth of cross-reactive neutralization by monoclonal antibodies, whether engineered or isolated from infected individuals. We chose from 200 southern African, clade C envelope-pseudotyped viruses with neutralization titers against 16 broadly neutralizing antibodies and 30 sera from chronic clade C infections. We selected panels to represent the diversity of bnAb neutralization profiles and Env neutralization sensitivities. Use of standard virus panels can facilitate comparison of results across studies and sites.

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