scholarly journals A lipid nanoparticle RBD-hFc mRNA vaccine protects hACE2 transgenic mice against lethal SARS-CoV-2 infection

2021 ◽  
Author(s):  
Uri Elia ◽  
Shahar Rotem ◽  
Erez Bar-Haim ◽  
Srinivas Ramishetti ◽  
Gonna Somu Naidu ◽  
...  
Keyword(s):  
Animal Models ◽  
Viral Replication ◽  
Neutralizing Antibodies ◽  
Protective Efficacy ◽  
Lethal Dose ◽  
Humoral Response ◽  
Receptor Binding Domain ◽  
Efficacy Data ◽  
Phase 3 ◽  
Mild Disease

The current global COVID-19 pandemic led to an unprecedented effort to develop effective vaccines against SARS-CoV-2. mRNA vaccines were developed very rapidly during the last year, and became the leading immunization platform against the virus, with highly promising phase-3 results and remarkable efficacy data. Since most animal models are not susceptible to SARS CoV-2 infection, pre-clinical studies are often limited to infection-prone animals such as hamsters and non-human primates. In these animal models, SARS-CoV-2 infection results in viral replication and a mild disease disease. Therefore, the protective efficacy of the vaccine in these animals is commonly evaluated by its ability to elicit immunologic responses, diminish viral replication and prevent weight loss. Our lab recently reported the design of a SARS-CoV-2 human Fc-conjugated receptor-binding domain (RBD-hFc) mRNA vaccine delivered via lipid nanoparticles (LNPs). These experiments demonstrated the development of a robust and specific immunologic response in RBD-hFc mRNA- vaccinated BALB/c mice. In the current study, we evaluated the protective effect of this RBD-hFc mRNA vaccine by employing the K18-hACE2 mouse model. We report that administration of RBD-hFc mRNA vaccine to K18-hACE2 mice led to a robust humoral response comprised of both binding and neutralizing antibodies. In accordance with the recorded immunologic immune response, 70% of vaccinated mice were protected against a lethal dose (3000 plaque forming units) of SARS-CoV-2, while all control animals succumbed to infection. To the best of our knowledge, this is the first non-replicating mRNA vaccine study reporting protection of K18-hACE2 against a lethal SARS-CoV-2 infection.

scholarly journals Rapid seroconversion and persistent functional IgG antibodies in severe COVID-19 patients correlates with an IL-12p70 and IL-33 signature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ariel Munitz ◽  
L. Edry-Botzer ◽  
M. Itan ◽  
R. Tur-Kaspa ◽  
D. Dicker ◽  
...  
Keyword(s):  
Nucleocapsid Protein ◽  
Neutralizing Antibodies ◽  
Host Response ◽  
Humoral Response ◽  
Rapid Onset ◽  
Response Analysis ◽  
Receptor Binding Domain ◽  
Igg Antibodies ◽  
Viral Receptor ◽  
Iga Antibodies

AbstractDespite ongoing efforts to characterize the host response toward SARS-CoV-2, a major gap in our knowledge still exists regarding the magnitude and duration of the humoral response. Analysis of the antibody response in mild versus moderate/severe patients, using our new developed quantitative electrochemiluminescent assay for detecting IgM/IgA/IgG antibodies toward SARS-CoV-2 antigens, revealed a rapid onset of IgG/IgA antibodies, specifically in moderate/severe patients. IgM antibodies against the viral receptor binding domain, but not against nucleocapsid protein, were detected at early stages of the disease. Furthermore, we observed a marked reduction in IgM/IgA antibodies over-time. Adapting our assay for ACE2 binding-competition, demonstrated that the presence of potentially neutralizing antibodies is corelated with IgG/IgA. Finally, analysis of the cytokine profile in COVID-19 patients revealed unique correlation of an IL-12p70/IL33 and IgG seroconversion, which correlated with disease severity. In summary, our comprehensive analysis has major implications on the understanding and monitoring of SARS-CoV-2 infections.

scholarly journals Characterization of Neutralizing Antibodies and Identification of Neutralizing Epitope Mimics on the Clostridium botulinum Neurotoxin Type A

2001 ◽  
Vol 67 (7) ◽  
pp. 3201-3207 ◽  
Author(s):  
Han-Chung Wu ◽  
Chia-Tsui Yeh ◽  
Yue-Ling Huang ◽  
Lih-Jeng Tarn ◽  
Chien-Cheng Lung
Keyword(s):  
Monoclonal Antibodies ◽  
Neutralizing Antibodies ◽  
Clostridium Botulinum ◽  
Neuromuscular Junctions ◽  
Competitive Inhibition ◽  
Lethal Dose ◽  
Humoral Response ◽  
Type A ◽  
Phage Clone ◽  
Neutralizing Epitopes

ABSTRACT Clostridium botulinum neurotoxin type A (BTx-A) is known to inhibit the release of acetylcholine at the neuromuscular junctions and synapses and to cause neuroparalysis and death. In this study, we have identified two monoclonal antibodies, BT57-1 and BT150-3, which protect ICR mice against lethal doses of BTx-A challenge. The neutralizing activities for BT57-1 and BT150-3 were 103 and 104 times the 50% lethal dose, respectively. Using immunoblotting analysis, BT57-1 was recognized as a light chain and BT150-3 was recognized as a heavy chain of BTx-A. Also, applying the phage display method, we investigated the antibodies' neutralizing B-cell epitopes. These immunopositive phage clones displayed consensus motifs, Asp-Pro-Leu for BT57-1 and Cys-X-Asp-Cys for BT150. The synthetic peptide P4M (KGTFDPLQEPRT) corresponded to the phage-displayed peptide selected by BT57-1 and was able to bind the antibodies specifically. This peptide was also shown by competitive inhibition assay to be able to inhibit phage clone binding to BT57-1. Aspartic acid (D5) in P4M was crucial to the binding of P4M to BT57-1, since its binding activity dramatically decreased when it was changed to lysine (K5). Finally, immunizing mice with the selected phage clones elicited a specific humoral response against BTx-A. These results suggest that phage-displayed random-peptide libraries are useful in identifying the neutralizing epitopes of monoclonal antibodies. In the future, the identification of the neutralizing epitopes of BTx-A may provide important information for the identification of the BTx-A receptor and the design of a BTx-A vaccine.

scholarly journals Serologic responses to SARS-CoV-2 infection among hospital staff with mild disease in eastern France

2020 ◽  
Author(s):  
Samira Fafi-Kremer ◽  
Timothee Bruel ◽  
Yoann Madec ◽  
Rebecca Grant ◽  
Laura Tondeur ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Neutralizing Antibodies ◽  
Rapid Test ◽  
Humoral Response ◽  
Hospital Staff ◽  
Sample Collection ◽  
Future Studies ◽  
Neutralizing Activity ◽  
Neutralization Capacity ◽  
Mild Disease

Background: The serologic response of individuals with mild forms of SARS-CoV-2 infection is poorly characterized. Methods: Hospital staff who had recovered from mild forms of PCR-confirmed SARS-CoV-2 infection were tested for anti-SARS-CoV-2 antibodies using two assays: a rapid immunodiagnostic test (99.4% specificity) and the S-Flow assay (~99% specificity).The neutralizing activity of the sera was tested with a pseudovirus-based assay. Results: Of 162 hospital staff who participated in the investigation, 160 reported SARS-CoV- 2 infection that had not required hospital admission and were included in these analyses. The median time from symptom onset to blood sample collection was 24 days (IQR: 21-28, range 13-39). The rapid immunodiagnostic test detected antibodies in 153 (95.6%) of the samples and the S-Flow assay in 159 (99.4%), failing to detect antibodies in one sample collected 18 days after symptom onset (the rapid test did not detect antibodies in that patient). Neutralizing antibodies (NAbs) were detected in 79%, 92% and 98% of samples collected 13-20, 21-27 and 28-41 days after symptom onset, respectively (P=0.02). Conclusion: Antibodies against SARS-CoV-2 were detected in virtually all hospital staff sampled from 13 days after the onset of COVID-19 symptoms. This finding supports the use of serologic testing for the diagnosis of individuals who have recovered from SARS-CoV-2 infection. The neutralizing activity of the antibodies increased overtime. Future studies will help assess the persistence of the humoral response and its associated neutralization capacity in recovered patients.

scholarly journals Intranasal inhibitor blocks Omicron and other variants of SARS-CoV-2

2021 ◽  
Author(s):  
Anna R Mäkelä ◽  
Hasan Uğurlu ◽  
Liina Hannula ◽  
Petja Salminen ◽  
Ravi Kant ◽  
...  
Keyword(s):  
Animal Models ◽  
Molecular Basis ◽  
Neutralizing Antibodies ◽  
Intranasal Administration ◽  
Inhibitory Action ◽  
Large Scale ◽  
Antibody Fragments ◽  
Protective Measure ◽  
Receptor Binding Domain ◽  
Target Epitope

The emergence of the SARS-CoV-2 Omicron variant capable of escaping neutralizing antibodies emphasizes the need for prophylactic strategies to complement vaccination in fighting the COVID-19 pandemic. Nasal epithelium is rich in the ACE2 receptor and important for SARS-CoV-2 transmission by supporting early viral replication before seeding to the lung. Intranasal administration of SARS-CoV-2 neutralizing antibodies or antibody fragments has shown encouraging potential as a protective measure in animal models. However, there remains a need for SARS-CoV-2 blocking agents that are more economical to produce in large scale, while less vulnerable to mutational variation in the neutralization epitopes of the viral Spike glycoprotein. Here we describe TriSb92, a highly manufacturable trimeric human nephrocystin SH3 domain-derived antibody mimetic targeted against a conserved region in the receptor-binding domain of the Spike. TriSb92 potently neutralizes SARS-CoV-2 and its variants of concern, including Delta and Omicron. Intranasal administration of a modest dose of TriSb92 (5 or 50 micrograms) as early as eight hours before the challenge with SARS-CoV-2 B.1.351 efficiently protected mice from infection. The target epitope of TriSb92 was defined by cryo-EM, which revealed triggering of a conformational shift in the Spike trimer rather than competition for ACE2 binding as the molecular basis of its strong inhibitory action. Our results highlight the potential of intranasal inhibitors in protecting susceptible individuals from SARS-CoV-2 infection, and describe a novel type of inhibitor that could be of use in addressing the challenge posed by the Omicron variant.

scholarly journals Design of SARS-CoV-2 RBD mRNA Vaccine Using Novel Ionizable Lipids

2020 ◽  
Author(s):  
Uri Elia ◽  
Srinivas Ramishetti ◽  
Niels Dammes ◽  
Erez Bar-Haim ◽  
Gonna Somu Naidu ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Cellular Response ◽  
Humoral Response ◽  
The Novel ◽  
Receptor Binding Domain ◽  
A Cell ◽  
Luciferase Mrna ◽  
Novel Coronavirus ◽  
High Level

AbstractThe novel coronavirus SARS-CoV-2 has been identified as the causal agent of COVID-19 and stands at the center of the current global human pandemic, with death toll exceeding one million. The urgent need for a vaccine has led to the development of various immunization approaches. mRNA vaccines represent a cell-free, simple and rapid platform for immunization, and therefore have been employed in recent studies towards the development of a SARS-CoV-2 vaccine. In this study, we present the design of a lipid nanoparticles (LNP)-encapsulated receptor binding domain (RBD) mRNA vaccine. Several ionizable lipids have been evaluated in vivo in a luciferase mRNA reporter assay, and two leading LNPs formulation have been chosen for the subsequent RBD mRNA vaccine experiment. Intramuscular administration of LNP RBD mRNA elicited robust humoral response, high level of neutralizing antibodies and a Th1-biased cellular response in BALB/c mice. These novel lipids open new avenues for mRNA vaccines in general and for a COVID19 vaccine in particular.

scholarly journals Potent SARS-CoV-2 neutralizing antibodies with protective efficacy against newly emerged mutational variants

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tingting Li ◽  
Xiaojian Han ◽  
Chenjian Gu ◽  
Hangtian Guo ◽  
Huajun Zhang ◽  
...  
Keyword(s):  
Weight Loss ◽  
Monoclonal Antibodies ◽  
Structural Analysis ◽  
Transgenic Mice ◽  
Neutralizing Antibodies ◽  
Immune Escape ◽  
Protective Efficacy ◽  
Receptor Binding Domain ◽  
Prophylactic Efficacy ◽  
Unique Mechanism

AbstractAccumulating mutations in the SARS-CoV-2 Spike (S) protein can increase the possibility of immune escape, challenging the present COVID-19 prophylaxis and clinical interventions. Here, 3 receptor binding domain (RBD) specific monoclonal antibodies (mAbs), 58G6, 510A5 and 13G9, with high neutralizing potency blocking authentic SARS-CoV-2 virus display remarkable efficacy against authentic B.1.351 virus. Surprisingly, structural analysis has revealed that 58G6 and 13G9 both recognize the steric region S470–495 on the RBD, overlapping the E484K mutation presented in B.1.351. Also, 58G6 directly binds to another region S450–458 in the RBD. Significantly, 58G6 and 510A5 both demonstrate prophylactic efficacy against authentic SARS-CoV-2 and B.1.351 viruses in the transgenic mice expressing human ACE2 (hACE2), protecting weight loss and reducing virus loads. Together, we have evidenced 2 potent neutralizing Abs with unique mechanism targeting authentic SARS-CoV-2 mutants, which can be promising candidates to fulfill the urgent needs for the prolonged COVID-19 pandemic.

scholarly journals Nonhuman primate to human immunobridging to infer the protective effect of an Ebola virus vaccine candidate

npj Vaccines ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Ramon Roozendaal ◽  
Jenny Hendriks ◽  
Thierry van Effelterre ◽  
Bart Spiessens ◽  
Liesbeth Dekking ◽  
...  
Keyword(s):  
Protective Effect ◽  
Neutralizing Antibodies ◽  
Ebola Virus ◽  
Protective Efficacy ◽  
Published Data ◽  
Efficacy Data ◽  
Vaccine Regimen ◽  
Binding Antibody ◽  
Vaccine Immunogenicity ◽  
Antibody Levels

AbstractIt has been proven challenging to conduct traditional efficacy trials for Ebola virus (EBOV) vaccines. In the absence of efficacy data, immunobridging is an approach to infer the likelihood of a vaccine protective effect, by translating vaccine immunogenicity in humans to a protective effect, using the relationship between vaccine immunogenicity and the desired outcome in a suitable animal model. We here propose to infer the protective effect of the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen with an 8-week interval in humans by immunobridging. Immunogenicity and protective efficacy data were obtained for Ad26.ZEBOV and MVA-BN-Filo vaccine regimens using a fully lethal EBOV Kikwit challenge model in cynomolgus monkeys (nonhuman primates [NHP]). The association between EBOV neutralizing antibodies, glycoprotein (GP)-binding antibodies, and GP-reactive T cells and survival in NHP was assessed by logistic regression analysis. Binding antibodies against the EBOV surface GP were identified as the immune parameter with the strongest correlation to survival post EBOV challenge, and used to infer the predicted protective effect of the vaccine in humans using published data from phase I studies. The human vaccine-elicited EBOV GP-binding antibody levels are in a range associated with significant protection against mortality in NHP. Based on this immunobridging analysis, the EBOV GP-specific-binding antibody levels elicited by the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen in humans will likely provide protection against EBOV disease.

scholarly journals Sex differences in the decline of neutralizing antibodies to SARS-CoV-2

2020 ◽  
Author(s):  
Ludivine Grzelak ◽  
Aurélie Velay ◽  
Yoann Madec ◽  
Floriane Gallais ◽  
Isabelle Staropoli ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Sex Differences ◽  
Neutralizing Antibodies ◽  
Humoral Response ◽  
Time Points ◽  
Mild Disease ◽  
Duration Of Protection ◽  
Antibody Levels ◽  
Post Onset ◽  
Over Time

The evolution of SARS-CoV-2 humoral response in infected individuals remains poorly characterized. Here, we performed a longitudinal study of sera from 308 RT-qPCR+ individuals with mild disease, collected at two time-points, up to 6 months post-onset of symptoms (POS). We performed two anti-S and one anti-N serology assays and quantified neutralizing antibodies (NAbs). At month 1 (M1), males, individuals > 50 years of age or with a body mass index (BMI) > 25 exhibited higher levels of antibodies. Antibody levels decreased over time. At M3-6, anti-S antibodies persisted in 99% of individuals while anti-N IgG were measurable in only 59% of individuals. The decline in anti-S and NAbs was faster in males than in females, independently of age and BMI. Our results show that some serology tests are less reliable overtime and suggest that the duration of protection after SARS-CoV-2 infection or vaccination will be different in women and men.

scholarly journals A non-neutralizing antibody broadly protects against influenza virus infection by engaging effector cells

2021 ◽  
Vol 17 (8) ◽  
pp. e1009724
Author(s):  
Yi-An Ko ◽  
Yueh-Hsiang Yu ◽  
Yen-Fei Wu ◽  
Yung-Chieh Tseng ◽  
Chia-Lin Chen ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Neutralizing Antibodies ◽  
Influenza A ◽  
Protective Efficacy ◽  
Lethal Dose ◽  
Influenza Virus Infection ◽  
Neutralizing Antibody ◽  
H1n1 Influenza ◽  
Influenza A Viruses

Hemagglutinin (HA) is the immunodominant protein of the influenza virus. We previously showed that mice injected with a monoglycosylated influenza A HA (HAmg) produced cross-strain-reactive antibodies and were better protected than mice injected with a fully glycosylated HA (HAfg) during lethal dose challenge. We employed a single B-cell screening platform to isolate the cross-protective monoclonal antibody (mAb) 651 from mice immunized with the HAmg of A/Brisbane/59/2007 (H1N1) influenza virus (Bris/07). The mAb 651 recognized the head domain of a broad spectrum of HAs from groups 1 and 2 influenza A viruses and offered prophylactic and therapeutic efficacy against A/California/07/2009 (H1N1) (Cal/09) and Bris/07 infections in mice. The antibody did not possess neutralizing activity; however, antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis mediated by natural killer cells and alveolar macrophages were important in the protective efficacy of mAb 651. Together, this study highlighted the significance of effector functions for non-neutralizing antibodies to exhibit protection against influenza virus infection.

scholarly journals Efficacy of Coxsackievirus A5 Vaccine Candidates in an Actively Immunized Mouse Model

2021 ◽  
Author(s):  
Wei-Ping Jin ◽  
Jia Lu ◽  
Xiao-Yu Zhang ◽  
Jie Wu ◽  
Zhen-Ni Wei ◽  
...  
Keyword(s):  
Animal Model ◽  
Mouse Model ◽  
Neutralizing Antibodies ◽  
Large Scale ◽  
Vaccine Candidate ◽  
Protective Efficacy ◽  
Lethal Dose ◽  
Enterovirus 71 ◽  
Vaccine Candidates ◽  
Enterovirus Serotypes

Coxsackievirus A5 (CV-A5) has recently emerged as a main hand, foot and mouth disease (HFMD) pathogen. Following a large-scale vaccination campaign against enterovirus 71 (EV-71) in China, the number of HFMD-associated cases with EV-71 was reduced, especially severe and fatal cases. However, the total number of HFMD cases remains high, as HFMD is also caused by other enterovirus serotypes. A multivalent HFMD vaccine containing 4 or 6 antigens of enterovirus serotypes is urgently needed. A formaldehyde-inactivated CV-A5 vaccine derived from Vero cells was used to inoculate newborn Kunming mice on days 3 and 10. The mice were challenged on day 14 with a mouse-adapted CV-A5 strain at a lethal dose, which was lethal for 14-day-old suckling mice. Within 14 days post-challenge, groups of mice immunized with three formulations, empty particles (EPs), full particles (FPs) and a mixture of the EP and FP vaccine candidates, all survived, while 100% of the mock-immunized mice died. Neutralizing antibodies (NtAbs) were detected in the sera of immunized mice, and the NtAb levels were correlated with the survival rate of the challenged mice. The virus loads in organs were reduced, and pathological changes and viral protein expression were weak or not observed in the immunized mice compared with those in alum-inoculated control mice. Another interesting finding was the identification of CV-A5 dense particles (DPs), facilitating morphogenesis study. These results demonstrated that the Vero cell-adapted CV-A5 strain is a promising vaccine candidate and could be used as a multivalent HFMD vaccine component in the future. IMPORTANCE The vaccine candidate strain CV-A5 was produced with a high infectivity titer and a high viral particle yield. Three particle forms, empty particles (EPs), full particles (FPs) and dense particles (DPs), were obtained and characterized after purification. The immunogenicities of EP, FP, and EP+FP were evaluated in mice. Mouse-adapted CV-A5 was generated as a challenge strain to infect 14-day-old mice. An active immunization challenge mouse model was established to evaluate the efficacy of the inactivated vaccine candidate. This animal model mimics vaccination, similar immune responses of the vaccinated. The animal model also tests protective efficacy in response to the vaccine against the disease. This work is important for the preparation of multivalent vaccines against HFMD caused by different emerging strains.

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