A Bacterial Flagellin, Vibrio vulnificus FlaB, Has a Strong Mucosal Adjuvant Activity To Induce Protective Immunity

ABSTRACT Flagellin, the structural component of flagellar filament in various locomotive bacteria, is the ligand for Toll-like receptor 5 (TLR5) of host cells. TLR stimulation by various pathogen-associated molecular patterns leads to activation of innate and subsequent adaptive immune responses. Therefore, TLR ligands are considered attractive adjuvant candidates in vaccine development. In this study, we show the highly potent mucosal adjuvant activity of a Vibrio vulnificus major flagellin (FlaB). Using an intranasal immunization mouse model, we observed that coadministration of the flagellin with tetanus toxoid (TT) induced significantly enhanced TT-specific immunoglobulin A (IgA) responses in both mucosal and systemic compartments and IgG responses in the systemic compartment. The mice immunized with TT plus FlaB were completely protected from systemic challenge with a 200× minimum lethal dose of tetanus toxin. Radiolabeled FlaB administered into the nasal cavity readily reached the cervical lymph nodes and systemic circulation. FlaB bound directly to human TLR5 expressed on cultured epithelial cells and consequently induced NF-κB and interleukin-8 activation. Intranasally administered FlaB colocalized with CD11c as patches in putative dendritic cells and caused an increase in the number of TLR5-expressing cells in cervical lymph nodes. These results indicate that flagellin would serve as an efficacious mucosal adjuvant inducing protective immune responses through TLR5 activation.

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Immune Responses to Irradiated Pneumococcal Whole Cell Vaccine

Vaccines ◽

10.3390/vaccines9040405 ◽

2021 ◽

Vol 9 (4) ◽

pp. 405

Author(s):

Eunbyeol Ko ◽

Soyoung Jeong ◽

Min Yong Jwa ◽

A Reum Kim ◽

Ye-Eun Ha ◽

...

Keyword(s):

Immune Responses ◽

Lymph Nodes ◽

T Cell Activation ◽

Lethal Dose ◽

Cell Vaccine ◽

Effective Vaccine ◽

Cervical Lymph Nodes ◽

Whole Cell ◽

Follicular Helper ◽

Whole Cell Vaccine

Streptococcus pneumoniae (pneumococcus) can cause respiratory and systemic diseases. Recently, γ-irradiation-inactivated, non-encapsulated, intranasal S. pneumoniae (r-SP) vaccine has been introduced as a novel serotype-independent and cost-effective vaccine. However, the immunogenic mechanism of r-SP is poorly understood. Here, we comparatively investigated the protective immunity and immunogenicity of r-SP to the heat-(h-SP) or formalin-inactivated vaccine (f-SP) without adjuvants. Mice were intranasally immunized with each vaccine three times and then challenged with a lethal dose of S. pneumoniae TIGR4 strain and then subsequently evaluated for their immune responses. Immunization with r-SP elicited modestly higher protection against S. pneumoniae than h-SP or f-SP. Immunization with r-SP enhanced pneumococcal-specific IgA in the nasal wash and IgG in bronchoalveolar lavage fluid. Immunization with r-SP enhanced S. pneumoniae-specific IgG, IgG1, and IgG2b in the serum. r-SP more potently induced the maturation of dendritic cells in the cervical lymph nodes than h-SP or f-SP. Interestingly, populations of follicular helper T cells and IL-4-producing cells were potently increased in cervical lymph nodes of r-SP-immunized mice. Collectively, r-SP could be an effective intranasal, inactivated whole-cell vaccine in that it elicits S. pneumoniae-specific antibody production and follicular helper T cell activation leading to protective immune responses against S. pneumoniae infection.

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Induction of Protective Antiplague Immune Responses by Self-Adjuvanting Bionanoparticles Derived from Engineered Yersinia pestis

Infection and Immunity ◽

10.1128/iai.00081-20 ◽

2020 ◽

Vol 88 (5) ◽

Cited By ~ 2

Author(s):

Xiuran Wang ◽

Amit K. Singh ◽

Xiangmin Zhang ◽

Wei Sun

Keyword(s):

Immune Responses ◽

Yersinia Pestis ◽

Rational Design ◽

Lipid A ◽

Vaccine Development ◽

Lethal Dose ◽

Outer Membrane Vesicles ◽

Vector System ◽

Content Type ◽

Monophosphoryl Lipid A

ABSTRACT A Yersinia pestis mutant synthesizing an adjuvant form of lipid A (monophosphoryl lipid A, MPLA) displayed increased biogenesis of bacterial outer membrane vesicles (OMVs). To enhance the immunogenicity of the OMVs, we constructed an Asd-based balanced-lethal host-vector system that oversynthesized the LcrV antigen of Y. pestis, raised the amounts of LcrV enclosed in OMVs by the type II secretion system, and eliminated harmful factors like plasminogen activator (Pla) and murine toxin from the OMVs. Vaccination with OMVs containing MPLA and increased amounts of LcrV with diminished toxicity afforded complete protection in mice against subcutaneous challenge with 8 × 105 CFU (80,000 50% lethal dose [LD50]) and intranasal challenge with 5 × 103 CFU (50 LD50) of virulent Y. pestis. This protection was significantly superior to that resulting from vaccination with LcrV/alhydrogel or rF1-V/alhydrogel. At week 4 postimmunization, the OMV-immunized mice showed more robust titers of antibodies against LcrV, Y. pestis whole-cell lysate (YPL), and F1 antigen and more balanced IgG1:IgG2a/IgG2b-derived Th1 and Th2 responses than LcrV-immunized mice. Moreover, potent adaptive and innate immune responses were stimulated in the OMV-immunized mice. Our findings demonstrate that self-adjuvanting Y. pestis OMVs provide a novel plague vaccine candidate and that the rational design of OMVs could serve as a robust approach for vaccine development.

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Coronavirus Nsp1: Immune Response Suppression and Protein Expression Inhibition

Frontiers in Microbiology ◽

10.3389/fmicb.2021.752214 ◽

2021 ◽

Vol 12 ◽

Author(s):

Shuai Yuan ◽

Shravani Balaji ◽

Ivan B. Lomakin ◽

Yong Xiong

Keyword(s):

Immune Responses ◽

Protein Expression ◽

Vaccine Development ◽

Nonstructural Protein ◽

Global Gene Expression ◽

Current Data ◽

Host Protein ◽

Host Cells ◽

Live Attenuated Vaccine ◽

Nonstructural Protein 1

Coronaviruses have brought severe challenges to public health all over the world in the past 20years. SARS-CoV-2, the causative agent of the COVID-19 pandemic that has led to millions of deaths, belongs to the genus beta-coronavirus. Alpha- and beta-coronaviruses encode a unique protein, nonstructural protein 1 (Nsp1) that both suppresses host immune responses and reduces global gene expression levels in the host cells. As a key pathogenicity factor of coronaviruses, Nsp1 redirects the host translation machinery to increase synthesis of viral proteins. Through multiple mechanisms, coronaviruses impede host protein expression through Nsp1, while escaping inhibition to allow the translation of viral RNA. In this review, we discuss current data about suppression of the immune responses and inhibition of protein synthesis induced by coronavirus Nsp1, as well as the prospect of live-attenuated vaccine development with virulence-attenuated viruses with mutations in Nsp1.

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Evaluation of the Pharmacokinetics of Intranasal Drug Delivery for Targeting Cervical Lymph Nodes in Rats

Pharmaceutics ◽

10.3390/pharmaceutics13091363 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1363

Author(s):

Tomoyuki Furubayashi ◽

Daisuke Inoue ◽

Shunsuke Kimura ◽

Akiko Tanaka ◽

Toshiyasu Sakane

Keyword(s):

Lymph Nodes ◽

Nasal Cavity ◽

Nasal Mucosa ◽

Intranasal Administration ◽

Systemic Circulation ◽

Nasal Delivery ◽

Pharmacokinetic Analysis ◽

Cervical Lymph Nodes ◽

Lymphatic Network ◽

Model Drug

A well-developed lymphatic network is located under the nasal mucosa, and a few drugs that permeate the nasal mucosa are absorbed into the lymphatic capillaries. Lymph from the nasal cavity flows to the cervical lymph nodes (CLNs). In this study, we evaluated the pharmacokinetics of the direct transport of intranasally administered drugs to CLNs through the nasal mucosa of Wistar rats using methotrexate as a model drug. The drug targeting index, which was calculated based on the areas under the concentration–time curves after intravenous and intranasal administration, was 3.78, indicating the benefits of nasal delivery of methotrexate to target CLNs. The direct transport percentage, which was indicative of the contribution of the direct nose–CLN pathway of methotrexate after intranasal administration, was 74.3%. The rate constant of methotrexate from the nasal cavity to CLNs was 0.0047 ± 0.0013 min−1, while that from systemic circulation to CLNs was 0.0021 ± 0.0009 min−1. Through pharmacokinetic analysis, this study demonstrated that the direct nasal–CLN pathway contributed more to the transport of methotrexate to the CLNs than the direct blood–CLN pathway.

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Immunogenicity and Persistence of a Targeted Anti-caries DNA Vaccine

Journal of Dental Research ◽

10.1177/154405910608501008 ◽

2006 ◽

Vol 85 (10) ◽

pp. 915-918 ◽

Cited By ~ 12

Author(s):

Q.A. Xu ◽

F. Yu ◽

M.W. Fan ◽

Z. Bian ◽

Z. Chen ◽

...

Keyword(s):

Immune Responses ◽

Lymph Nodes ◽

Dna Vaccine ◽

Antibody Responses ◽

Cervical Lymph Nodes ◽

Booster Immunization ◽

Inoculation Site ◽

The Us ◽

Kinetics Of ◽

Draining Lymph Nodes

We have previously reported that a targeted anti-caries DNA vaccine, pGJA-P, induced accelerated and increased antibody responses compared with a non-targeted anti-caries DNA vaccine. Recently, pGJA-P/VAX, a new targeted anti-caries DNA vaccine for human trials, was constructed by replacing the pCI vector used in the construction of pGJA-P with pVAX1, the only vector authorized by the US Food and Drug Administration in clinical trials. Here, we report on our exploration of the kinetics of the antibody responses generated following pGJA-P/VAX immunization and the persistence of pGJA-P/VAX at both the inoculation site and the draining lymph nodes. Intranasal vaccination of mice with pGJA-P/VAX induced strong antibody responses that lasted for more than 6 months. Furthermore, pGJA-P/VAX could still be detected at both the inoculation site and the draining cervical lymph nodes 6 months after immunization. Thus, the persistent immune responses are likely due to the DNA depot in the host, which acts as a booster immunization.

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Self-Amplifying RNA Viruses as RNA Vaccines

International Journal of Molecular Sciences ◽

10.3390/ijms21145130 ◽

2020 ◽

Vol 21 (14) ◽

pp. 5130 ◽

Cited By ~ 4

Author(s):

Kenneth Lundstrom

Keyword(s):

Immune Responses ◽

Viral Vectors ◽

Ebola Virus ◽

Tumor Antigens ◽

Vaccine Development ◽

Rna Viruses ◽

Emerging Diseases ◽

Host Cells ◽

Phase Iii ◽

Rna Replicon

Single-stranded RNA viruses such as alphaviruses, flaviviruses, measles viruses and rhabdoviruses are characterized by their capacity of highly efficient self-amplification of RNA in host cells, which make them attractive vehicles for vaccine development. Particularly, alphaviruses and flaviviruses can be administered as recombinant particles, layered DNA/RNA plasmid vectors carrying the RNA replicon and even RNA replicon molecules. Self-amplifying RNA viral vectors have been used for high level expression of viral and tumor antigens, which in immunization studies have elicited strong cellular and humoral immune responses in animal models. Vaccination has provided protection against challenges with lethal doses of viral pathogens and tumor cells. Moreover, clinical trials have demonstrated safe application of RNA viral vectors and even promising results in rhabdovirus-based phase III trials on an Ebola virus vaccine. Preclinical and clinical applications of self-amplifying RNA viral vectors have proven efficient for vaccine development and due to the presence of RNA replicons, amplification of RNA in host cells will generate superior immune responses with significantly reduced amounts of RNA delivered. The need for novel and efficient vaccines has become even more evident due to the global COVID-19 pandemic, which has further highlighted the urgency in challenging emerging diseases.

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Vaccines against Coronavirus Disease: Target Proteins, Immune Responses, and Status of Ongoing Clinical Trials

Journal of Pure and Applied Microbiology ◽

10.22207/jpam.14.4.03 ◽

2020 ◽

Vol 14 (4) ◽

pp. 2253-2263

Author(s):

Rike Syahniar ◽

Maria Berlina Purba ◽

Heri Setiyo Bekti ◽

Mardhia Mardhia

Keyword(s):

Clinical Trials ◽

Immune Responses ◽

Neutralizing Antibodies ◽

Vaccine Development ◽

Host Cells ◽

Rapid Transmission ◽

Adequate Dosage ◽

Immunogenic Response ◽

Selection Of

The coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has infected more than 26 million individuals and caused 871,166 deaths globally. Various countries are racing against time to find a vaccine for controlling the rapid transmission of infection. The selection of antigen targets to trigger an immune response is crucial for vaccine development strategies. The receptor binding domain of the subunit of spike 1 protein is considered a promising vaccine candidate because of its ability to prevent attachment and infection of host cells by stimulating neutralizing antibodies. The vaccine is expected to mount a sufficient immunogenic response to eliminate the virus and store antigenic information in memory cells for long-term protection. Here, we review the ongoing clinical trials for COVID-19 vaccines and discuss the immune responses in patients administered an adequate dosage to prevent COVID-19.

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MARTX Toxin-Stimulated Interplay between Human Cells and Vibrio vulnificus

mSphere ◽

10.1128/msphere.00659-20 ◽

2020 ◽

Vol 5 (4) ◽

Cited By ~ 1

Author(s):

Byoung Sik Kim ◽

Jong-Hwan Kim ◽

Sanghyeon Choi ◽

Shinhye Park ◽

Eun-Young Lee ◽

...

Keyword(s):

Immune Responses ◽

Immune Cells ◽

Vibrio Vulnificus ◽

Expression Profiles ◽

Host Cells ◽

Iron Limitation ◽

Host Pathogen Interactions ◽

Content Type ◽

Host Pathogen ◽

Ht 29

ABSTRACT To understand toxin-stimulated host-pathogen interactions, we performed dual-transcriptome sequencing experiments using human epithelial (HT-29) and differentiated THP-1 (dTHP-1) immune cells infected with the sepsis-causing pathogen Vibrio vulnificus (either the wild-type [WT] pathogen or a multifunctional-autoprocessing repeats-in-toxin [MARTX] toxin-deficient strain). Gene set enrichment analyses revealed MARTX toxin-dependent responses, including negative regulation of extracellular related kinase 1 (ERK1) and ERK2 (ERK1/2) signaling and cell cycle regulation in HT-29 and dTHP-1 cells, respectively. Further analysis of the expression of immune-related genes suggested that the MARTX toxin dampens immune responses in gut epithelial cells but accelerates inflammation and nuclear factor κB (NF-κB) signaling in immune cells. With respect to the pathogen, siderophore biosynthesis genes were significantly more highly expressed in WT V. vulnificus than in the MARTX toxin-deficient mutant upon infection of dTHP-1 cells. Consistent with these results, iron homeostasis genes that limit iron levels for invading pathogens were overexpressed in WT V. vulnificus-infected dTHP-1 cells. Taken together, these results suggest that MARTX toxin regulates host inflammatory responses during V. vulnificus infection while also countering host defense mechanisms such as iron limitation. IMPORTANCE V. vulnificus is an opportunistic human pathogen that can cause life-threatening sepsis in immunocompromised patients via seafood poisoning or wound infection. Among the toxic substances produced by this pathogen, the MARTX toxin greatly contributes to disease progression by promoting the dysfunction and death of host cells, which allows the bacteria to disseminate and colonize the host. In response to this, host cells mount a counterattack against the invaders by upregulating various defense genes. In this study, the gene expression profiles of both host cells and V. vulnificus were analyzed by RNA sequencing to gain a comprehensive understanding of host-pathogen interactions. Our results suggest that V. vulnificus uses the MARTX toxin to subvert host cell immune responses as well as to oppose host counterattacks such as iron limitation.

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An Intranasally Delivered Toll-Like Receptor 7 Agonist Elicits Robust Systemic and Mucosal Responses to Norwalk Virus-Like Particles

Clinical and Vaccine Immunology ◽

10.1128/cvi.00230-10 ◽

2010 ◽

Vol 17 (12) ◽

pp. 1850-1858 ◽

Cited By ~ 33

Author(s):

Lissette S. Velasquez ◽

Brooke E. Hjelm ◽

Charles J. Arntzen ◽

Melissa M. Herbst-Kralovetz

Keyword(s):

Immune Responses ◽

Immune Protection ◽

Norwalk Virus ◽

Toll Like Receptor ◽

Adjuvant Activity ◽

Mucosal Adjuvant ◽

Virus Like Particles ◽

Vaccine Trials ◽

Specific Serum ◽

Tlr7 Agonist

ABSTRACT Norwalk virus (NV) is an enteric pathogen from the genus Norovirus and a major cause of nonbacterial gastroenteritis in humans. NV virus-like particles (VLPs) are known to elicit systemic and mucosal immune responses when delivered nasally; however, the correlates of immune protection are unknown, and codelivery with a safe and immunogenic mucosal adjuvant may enhance protective anti-NV immune responses. Resiquimod (R848), an imidazoquinoline-based Toll-like receptor 7 and/or 8 (TLR7/8) agonist, is being evaluated as an adjuvant in FDA-approved clinical vaccine trials. As such, we evaluated the adjuvant activity of two imidazoquinoline-based TLR7 and TLR7/8 agonists when codelivered intranasally with plant-derived NV VLPs. We also compared the activity of these agonists to the gold standard mucosal adjuvant, cholera toxin (CT). Our results indicate that codelivery with the TLR7 agonist, gardiquimod (GARD), induces NV VLP-specific serum IgG and IgG isotype responses and mucosal IgA responses in the gastrointestinal, respiratory, and reproductive tracts that are superior to those induced by R848 and comparable to those induced by the mucosal adjuvant CT. This study supports the continued investigation of GARD as a mucosal adjuvant for NV VLPs and possible use for other VLP-based vaccines for which immune responses at distal mucosal sites (e.g., respiratory and reproductive tracts) are desired.

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Identification of OmpU of Vibrio vulnificus as a Fibronectin-Binding Protein and Its Role in Bacterial Pathogenesis

Infection and Immunity ◽

10.1128/iai.00171-06 ◽

2006 ◽

Vol 74 (10) ◽

pp. 5586-5594 ◽

Cited By ~ 63

Author(s):

Sung Young Goo ◽

Hyun-Ju Lee ◽

Woo Hwang Kim ◽

Kyu-Lee Han ◽

Dae-Kyun Park ◽

...

Keyword(s):

Mammalian Cells ◽

Vibrio Vulnificus ◽

Outer Membrane Proteins ◽

Lethal Dose ◽

Fold Increase ◽

Host Cells ◽

Wild Type ◽

Binding Assays ◽

Exogenous Addition ◽

Main Components

ABSTRACT Vibrio vulnificus is a pathogenic bacterium that causes gastroenteritis and primary septicemia. To identify factors involved in microbial adherence to the host cells, we investigated bacterial proteins capable of binding to fibronectin, one of the main components comprised of the extracellular matrix of mammalian cells. A protein of ∼35 kDa was purified from the extracts of V. vulnificus by its property to bind to immobilized fibronectin. This protein was identified as OmpU, one of the major outer membrane proteins of V. vulnificus. In binding assays using immobilized fibronectin, the number of ompU mutant cells bound to fibronectin was only 4% of that of wild-type cells bound to fibronectin. In addition, the exogenous addition of antibodies against OmpU resulted in a decreased ability of wild-type V. vulnificus to adhere to fibronectin. The ompU mutant was also defective in its adherence to RGD tripeptide (5% of the adherence of the wild type to RGD), cytoadherence to HEp-2 cells (7% of the adherence of the wild type to HEp-2), cytotoxicity to cell cultures (39% of the cytotoxicity of the wild type), and mortality in mice (10-fold increase in the 50% lethal dose). The ompU mutant complemented with the intact ompU gene restored its abilities for adherence to fibronectin, RGD tripeptide, and HEp-2 cells; cytotoxicity to HEp-2 cells; and mouse lethality. This study indicates that OmpU is an important virulence factor involved in the adherence of V. vulnificus to the host cells.

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