scholarly journals Immunisation of ferrets and mice with recombinant SARS-CoV-2 spike protein formulated with Advax-SM adjuvant protects against COVID-19 infection

2021 ◽  
Author(s):  
Lei Li ◽  
Yoshikazu Honda-Okubo ◽  
Ying Huang ◽  
Hyesun Jang ◽  
Michael A Carlock ◽  
...  
Keyword(s):  
Genomic Sequence ◽  
Cytotoxic T Lymphocyte ◽  
Virus Transmission ◽  
Spike Protein ◽  
Effective Vaccine ◽  
Target Cells ◽  
Protein Vaccine ◽  
Gene Encoding ◽  
Vaccine Approach

The development of a safe and effective vaccine is a key requirement to overcoming the COVID-19 pandemic. Recombinant proteins represent the most reliable and safe vaccine approach but generally require a suitable adjuvant for robust and durable immunity. We used the SARS-CoV-2 genomic sequence and in silico structural modelling to design a recombinant spike protein vaccine (Covax-19). A synthetic gene encoding the spike extracellular domain (ECD) was inserted into a baculovirus backbone to express the protein in insect cell cultures. The spike ECD was formulated with Advax-SM adjuvant and first tested for immunogenicity in C57BL/6 and BALB/c mice. The Advax-SM adjuvanted vaccine induced high titers of binding antibody against spike protein that were able to neutralise the original wildtype virus on which the vaccine was based as well as the variant B.1.1.7 lineage virus. The Covax-19 vaccine also induced potent spike-specific CD4+ and CD8+ memory T-cells with a dominant Th1 phenotype, and this was shown to be associated with cytotoxic T lymphocyte killing of spike labelled target cells in vivo. Ferrets immunised with Covax-19 vaccine intramuscularly twice 2 weeks apart made spike receptor binding domain (RBD) IgG and were protected against an intranasal challenge with SARS-CoV-2 virus 2 weeks after the second immunisation. Notably, ferrets that received two 25 or 50ug doses of Covax-19 vaccine had no detectable virus in their lungs or in nasal washes at day 3 post-challenge, suggesting the possibility that Covax-19 vaccine may in addition to protection against lung infection also have the potential to block virus transmission. This data supports advancement of Covax-19 vaccine into human clinical trials.

scholarly journals Environmental Restrictions: A New Concept Governing HIV-1 Spread Emerging from Integrated Experimental-Computational Analysis of Tissue-Like 3D Cultures

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1112 ◽  
Author(s):  
Samy Sid Ahmed ◽  
Nils Bundgaard ◽  
Frederik Graw ◽  
Oliver Fackler
Keyword(s):  
In Silico ◽  
Computational Analysis ◽  
Virus Transmission ◽  
Target Cells ◽  
Virus Spread ◽  
Transmission Modes ◽  
3D Collagen ◽  
Cell Densities ◽  
Hiv 1

HIV-1 can use cell-free and cell-associated transmission modes to infect new target cells, but how the virus spreads in the infected host remains to be determined. We recently established 3D collagen cultures to study HIV-1 spread in tissue-like environments and applied iterative cycles of experimentation and computation to develop a first in silico model to describe the dynamics of HIV-1 spread in complex tissue. These analyses (i) revealed that 3D collagen environments restrict cell-free HIV-1 infection but promote cell-associated virus transmission and (ii) defined that cell densities in tissue dictate the efficacy of these transmission modes for virus spread. In this review, we discuss, in the context of the current literature, the implications of this study for our understanding of HIV-1 spread in vivo, which aspects of in vivo physiology this integrated experimental–computational analysis takes into account, and how it can be further improved experimentally and in silico.

scholarly journals Quantitating the Multiplicity of Infection with Human Immunodeficiency Virus Type 1 Subtype C Reveals a Non-Poisson Distribution of Transmitted Variants

2009 ◽  
Vol 83 (8) ◽  
pp. 3556-3567 ◽  
Author(s):  
M.-R. Abrahams ◽  
J. A. Anderson ◽  
E. E. Giorgi ◽  
C. Seoighe ◽  
K. Mlisana ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Poisson Distribution ◽  
Cytotoxic T Lymphocyte ◽  
Virus Transmission ◽  
Effective Vaccine ◽  
Subtype C ◽  
Genetic Characteristics ◽  
Subtype B ◽  
Independent Events ◽  
Immunodeficiency Virus

ABSTRACT Identifying the specific genetic characteristics of successfully transmitted variants may prove central to the development of effective vaccine and microbicide interventions. Although human immunodeficiency virus transmission is associated with a population bottleneck, the extent to which different factors influence the diversity of transmitted viruses is unclear. We estimate here the number of transmitted variants in 69 heterosexual men and women with primary subtype C infections. From 1,505 env sequences obtained using a single genome amplification approach we show that 78% of infections involved single variant transmission and 22% involved multiple variant transmissions (median of 3). We found evidence for mutations selected for cytotoxic-T-lymphocyte or antibody escape and a high prevalence of recombination in individuals infected with multiple variants representing another potential escape pathway in these individuals. In a combined analysis of 171 subtype B and C transmission events, we found that infection with more than one variant does not follow a Poisson distribution, indicating that transmission of individual virions cannot be seen as independent events, each occurring with low probability. While most transmissions resulted from a single infectious unit, multiple variant transmissions represent a significant fraction of transmission events, suggesting that there may be important mechanistic differences between these groups that are not yet understood.

scholarly journals Evaluation of CD8 T cell killing models with computer simulations of 2-photon imaging experiments

2020 ◽  
Vol 16 (12) ◽  
pp. e1008428
Author(s):  
Ananya Rastogi ◽  
Philippe A. Robert ◽  
Stephan Halle ◽  
Michael Meyer-Hermann
Keyword(s):  
Cytotoxic T Lymphocyte ◽  
Three Dimensional ◽  
Critical Factor ◽  
Target Cells ◽  
Agent Based ◽  
Multiple Contacts ◽  
Infected Cells ◽  
New Interactions ◽  
Increased Susceptibility

In vivo imaging of cytotoxic T lymphocyte (CTL) killing activity revealed that infected cells have a higher observed probability of dying after multiple contacts with CTLs. We developed a three-dimensional agent-based model to discriminate different hypotheses about how infected cells get killed based on quantitative 2-photon in vivo observations. We compared a constant CTL killing probability with mechanisms of signal integration in CTL or infected cells. The most likely scenario implied increased susceptibility of infected cells with increasing number of CTL contacts where the total number of contacts was a critical factor. However, when allowing in silico T cells to initiate new interactions with apoptotic target cells (zombie contacts), a contact history independent killing mechanism was also in agreement with experimental datasets. The comparison of observed datasets to simulation results, revealed limitations in interpreting 2-photon data, and provided readouts to distinguish CTL killing models.

scholarly journals Recombinant immunotoxins containing anti-Tac(Fv) and derivatives of Pseudomonas exotoxin produce complete regression in mice of an interleukin-2 receptor-expressing human carcinoma

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 426-434 ◽  
Author(s):  
RJ Kreitman ◽  
P Bailon ◽  
VK Chaudhary ◽  
DJ FitzGerald ◽  
I Pastan
Keyword(s):  
Interleukin 2 ◽  
Target Cells ◽  
Complete Regression ◽  
Single Chain ◽  
Pseudomonas Exotoxin ◽  
Gene Encoding ◽  
Human Carcinoma ◽  
Interleukin 2 Receptor ◽  
Variable Domains

Anti-Tac(Fv)-PE40 is a recombinant single-chain immunotoxin composed of the variable domains of the monoclonal antibody anti-Tac, which binds to the p55 subunit of the interleukin-2 receptor (IL-2R), and a truncated form of Pseudomonas exotoxin (PE), which does not bind to the PE receptor (Chaudhary et al, Nature 339:394, 1989). Whereas its cytotoxic activity toward autoimmune and malignant target cells has been established, its efficacy in vivo remains unknown. To establish an animal model, we produced ATAC-4 cells by transfecting the gene encoding the low-affinity IL-2R (p55) into A431 epidermoid carcinoma cells. ATAC-4 cells contained low-affinity IL-2Rs (2 x 10(5)/cell) and formed tumors in nude mice. In tissue culture, protein synthesis in ATAC-4 cells was inhibited 50% (IC50) at 0.06 ng/mL (0.9 pmol/L) of anti-Tac(Fv)-PE40. IC50s for the derivatives anti-Tac(Fv)-PE38, which is missing PE amino acids 365–380, and anti-Tac(Fv)-PE38KDEL, which contains the same deletion plus the KDEL carboxyl terminus, were 0.04 and 0.025 ng/mL, respectively. All the agents produced complete tumor regressions in ATAC-4 tumor-bearing mice and anti-Tac(Fv)-PE38KDEL had significant antitumor activity at 1% of the LD50. The dose limiting toxicity of anti-Tac(Fv)-PE38KDEL was from hemorrhagic liver necrosis, which was observed at approximately 55% of the LD50.

scholarly journals Exosome-Mediated mRNA Delivery For SARS-CoV-2 Vaccination

2020 ◽  
Author(s):  
Shang-Jui Tsai ◽  
Chenxu Guo ◽  
Nadia A. Atai ◽  
Stephen J. Gould
Keyword(s):  
Viral Vectors ◽  
Vaccine Development ◽  
Spike Protein ◽  
Interleukin 4 ◽  
Target Cells ◽  
Durable Response ◽  
Elevated Expression ◽  
Cellular Immune

AbstractBackgroundIn less than a year from its zoonotic entry into the human population, SARS-CoV-2 has infected more than 45 million people, caused 1.2 million deaths, and induced widespread societal disruption. Leading SARS-CoV-2 vaccine candidates immunize with the viral spike protein delivered on viral vectors, encoded by injected mRNAs, or as purified protein. Here we describe a different approach to SARS-CoV-2 vaccine development that uses exosomes to deliver mRNAs that encode antigens from multiple SARS-CoV-2 structural proteins.ApproachExosomes were purified and loaded with mRNAs designed to express (i) an artificial fusion protein, LSNME, that contains portions of the viral spike, nucleocapsid, membrane, and envelope proteins, and (ii) a functional form of spike. The resulting combinatorial vaccine, LSNME/SW1, was injected into thirteen weeks-old, male C57BL/6J mice, followed by interrogation of humoral and cellular immune responses to the SARS-CoV-2 nucleocapsid and spike proteins, as well as hematological and histological analysis to interrogate animals for possible adverse effects.ResultsImmunized mice developed CD4+, and CD8+ T-cell reactivities that respond to both the SARS-CoV-2 nucelocapsid protein and the SARS-CoV-2 spike protein. These responses were apparent nearly two months after the conclusion of vaccination, as expected for a durable response to vaccination. In addition, the spike-reactive CD4+ T-cells response was associated with elevated expression of interferon gamma, indicative of a Th1 response, and a lesser induction of interleukin 4, a Th2-associated cytokine. Vaccinated mice showed no sign of altered growth, injection-site hypersensitivity, change in white blood cell profiles, or alterations in organ morphology. Consistent with these results, we also detected moderate but sustained anti-nucleocapsid and anti-spike antibodies in the plasma of vaccinated animals.ConclusionTaken together, these results validate the use of exosomes for delivering functional mRNAs into target cells in vitro and in vivo, and more specifically, establish that the LSNME/SW1 vaccine induced broad immunity to multiple SARS-CoV-2 proteins.

scholarly journals Estimating In Vivo Death Rates of Targets due to CD8 T-Cell-Mediated Killing

2008 ◽  
Vol 82 (23) ◽  
pp. 11749-11757 ◽  
Author(s):  
Vitaly V. Ganusov ◽  
Rob J. De Boer
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Bacterial Infections ◽  
Cytotoxic T Lymphocyte ◽  
Cd8 T Cell ◽  
Target Cells ◽  
Published Data ◽  
Memory Cd8 T Cells

ABSTRACT Despite recent advances in immunology, several key parameters determining virus dynamics in infected hosts remain largely unknown. For example, the rate at which specific effector and memory CD8 T cells clear virus-infected cells in vivo is hardly known for any viral infection. We propose a framework to quantify T-cell-mediated killing of infected or peptide-pulsed target cells using the widely used in vivo cytotoxicity assay. We have reanalyzed recently published data on killing of peptide-pulsed splenocytes by cytotoxic T lymphocytes and memory CD8 T cells specific to NP396 and GP276 epitopes of lymphocytic choriomeningitis virus (LCMV) in the mouse spleen. Because there are so many effector CD8 T cells in spleens of mice at the peak of the immune response, NP396- and GP276-pulsed targets are estimated to have very short half-lives of 2 and 14 min, respectively. After the effector numbers have diminished, i.e., in LCMV-immune mice, the half-lives become 48 min and 2.8 h for NP396- and GP276-expressing targets, respectively. Analysis of several alternative models demonstrates that the estimates of half-life times of peptide-pulsed targets are not affected when changes are made in the model assumptions. Our report provides a unifying framework to compare killing efficacies of CD8 T-cell responses specific to different viral and bacterial infections in vivo, which may be used to compare efficacies of various cytotoxic-T-lymphocyte-based vaccines.

scholarly journals Virtual Screening of Phytochemicals by Targeting HR1 Domain of SARS-CoV-2 S Protein: Molecular Docking, Molecular Dynamics Simulations, and DFT Studies

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Arshia Majeed ◽  
Waqar Hussain ◽  
Farkhanda Yasmin ◽  
Ammara Akhtar ◽  
Nouman Rasool
Keyword(s):  
Molecular Dynamics ◽  
Molecular Docking ◽  
Molecular Dynamics Simulations ◽  
Density Functional ◽  
Spike Protein ◽  
Effective Vaccine ◽  
High Morbidity ◽  
Dynamics Simulations

The recent COVID-19 pandemic has impacted nearly the whole world due to its high morbidity and mortality rate. Thus, scientists around the globe are working to find potent drugs and designing an effective vaccine against COVID-19. Phytochemicals from medicinal plants are known to have a long history for the treatment of various pathogens and infections; thus, keeping this in mind, this study was performed to explore the potential of different phytochemicals as candidate inhibitors of the HR1 domain in SARS-CoV-2 spike protein by using computer-aided drug discovery methods. Initially, the pharmacological assessment was performed to study the drug-likeness properties of the phytochemicals for their safe human administration. Suitable compounds were subjected to molecular docking to screen strongly binding phytochemicals with HR1 while the stability of ligand binding was analyzed using molecular dynamics simulations. Quantum computation-based density functional theory (DFT) analysis was constituted to analyze the reactivity of these compounds with the receptor. Through analysis, 108 phytochemicals passed the pharmacological assessment and upon docking of these 108 phytochemicals, 36 were screened passing a threshold of -8.5 kcal/mol. After analyzing stability and reactivity, 5 phytochemicals, i.e., SilybinC, Isopomiferin, Lycopene, SilydianinB, and Silydianin are identified as novel and potent candidates for the inhibition of HR1 domain in SARS-CoV-2 spike protein. Based on these results, it is concluded that these compounds can play an important role in the design and development of a drug against COVID-19, after an exhaustive in vitro and in vivo examination of these compounds, in future.

scholarly journals CD4+ Target Cell Availability Determines the Dynamics of Immune Escape and Reversion In Vivo

2008 ◽  
Vol 82 (8) ◽  
pp. 4091-4101 ◽  
Author(s):  
Janka Petravic ◽  
Liyen Loh ◽  
Stephen J. Kent ◽  
Miles P. Davenport
Keyword(s):  
Human Immunodeficiency Virus ◽  
Immune Escape ◽  
Cytotoxic T Lymphocyte ◽  
Escape Mutation ◽  
Escape Mutant ◽  
Optimal Timing ◽  
Target Cells ◽  
Wild Type ◽  
Immunodeficiency Virus

ABSTRACT Infections with human immunodeficiency virus (HIV) and the closely related monkey viruses simian-human immunodeficiency virus (SHIV) and simian immunodeficiency virus (SIV) are characterized by progressive waves of immune responses, followed by viral mutation and “immune escape.” However, escape mutation usually leads to lower replicative fitness, and in the absence of immune pressure, an escape mutant (EM) virus “reverts” to the wild-type phenotype. Analysis of the dynamics of immune escape and reversion has suggested it is a mechanism for identifying the immunogens best capable of controlling viremia. We have analyzed and modeled data of the dynamics of wild-type (WT) and EM viruses during SHIV infection of macaques. Modeling suggests that the dynamics of reversion and immune escape should be determined by the availability of target cells for infection. Consistent with this suggestion, we find that the rate of reversion of cytotoxic T-lymphocyte (CTL) EM virus strongly correlates with the number of CD4+ T cells available for infection. This phenomenon also affects the rate of immune escape, since this rate is determined by the balance of CTL killing and the WT fitness advantage. This analysis predicts that the optimal timing for the selection of immune escape variants will be immediately after the peak of viremia and that the development of escape variants at later times will lead to slower selection. This has important implications for comparative studies of immune escape and reversion in different infections and for identifying epitopes with high fitness cost for use as vaccine targets.

scholarly journals The sequence at Spike S1/S2 site enables cleavage by furin and phospho-regulation in SARS-CoV2 but not in SARS-CoV1 or MERS-CoV

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mihkel Örd ◽  
Ilona Faustova ◽  
Mart Loog
Keyword(s):  
Viral Entry ◽  
Spike Protein ◽  
Target Cells ◽  
The Novel ◽  
Novel Coronavirus ◽  
Cleavage Motif ◽  
Left Middle ◽  
Surprising Finding

Abstract The Spike protein of the novel coronavirus SARS-CoV2 contains an insertion 680SPRRAR↓SV687 forming a cleavage motif RxxR for furin-like enzymes at the boundary of S1/S2 subunits. Cleavage at S1/S2 is important for efficient viral entry into target cells. The insertion is absent in other CoV-s of the same clade, including SARS-CoV1 that caused the 2003 outbreak. However, an analogous cleavage motif was present at S1/S2 of the Spike protein of the more distant Middle East Respiratory Syndrome coronavirus MERS-CoV. We show that a crucial third arginine at the left middle position, comprising a motif RRxR is required for furin recognition in vitro, while the general motif RxxR in common with MERS-CoV is not sufficient for cleavage. Further, we describe a surprising finding that the two serines at the edges of the insert SPRRAR↓SV can be efficiently phosphorylated by proline-directed and basophilic protein kinases. Both phosphorylations switch off furin’s ability to cleave the site. Although phospho-regulation of secreted proteins is still poorly understood, further studies, supported by a recent report of ten in vivo phosphorylated sites in the Spike protein of SARS-CoV2, could potentially uncover important novel regulatory mechanisms for SARS-CoV2.

scholarly journals Synthetic Long Peptide Derived from Mycobacterium tuberculosis Latency Antigen Rv1733c Protects against Tuberculosis

2015 ◽  
Vol 22 (9) ◽  
pp. 1060-1069 ◽  
Author(s):  
Mariateresa Coppola ◽  
Susan J. F. van den Eeden ◽  
Louis Wilson ◽  
Kees L. M. C. Franken ◽  
Tom H. M. Ottenhoff ◽  
...  
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
Protective Efficacy ◽  
Bacterial Load ◽  
Effective Vaccine ◽  
Protective Capacity ◽  
Content Type ◽  
Ifn Γ ◽  
Vaccine Approach

ABSTRACTResponsible for 9 million new cases of active disease and nearly 2 million deaths each year, tuberculosis (TB) remains a global health threat of overwhelming dimensions.Mycobacterium bovisBCG, the only licensed vaccine available, fails to confer lifelong protection and to prevent reactivation of latent infection. Although 15 new vaccine candidates are now in clinical trials, an effective vaccine against TB remains elusive, and new strategies for vaccination are vital. BCG vaccination fails to induce immunity againstMycobacterium tuberculosislatency antigens. Synthetic long peptides (SLPs) combined with adjuvants have been studied mostly for therapeutic cancer vaccines, yet not for TB, and proved to induce efficient antitumor immunity. This study investigated an SLP derived from Rv1733c, a majorM. tuberculosislatency antigen which is highly expressed by “dormant”M. tuberculosisand well recognized by T cells from latentlyM. tuberculosis-infected individuals. In order to assess itsin vivoimmunogenicity and protective capacity, Rv1733c SLP in CpG was administered to HLA-DR3 transgenic mice. Immunization with Rv1733c SLP elicited gamma interferon-positive/tumor necrosis factor-positive (IFN-γ+/TNF+) and IFN-γ+CD4+T cells and Rv1733c-specific antibodies and led to a significant reduction in the bacterial load in the lungs ofM. tuberculosis-challenged mice. This was observed both in a pre- and in a post-M. tuberculosischallenge setting. Moreover, Rv1733c SLP immunization significantly boosted the protective efficacy of BCG, demonstrating the potential ofM. tuberculosislatency antigens to improve BCG efficacy. These data suggest a promising role forM. tuberculosislatency antigen Rv1733c-derived SLPs as a novel TB vaccine approach, both in a prophylactic and in a postinfection setting.

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