Use of a Clostridioides difficile Murine Immunization and Challenge Model to Evaluate Single and Combination Vaccine Adjuvants Consisting of Alum and NKT Cell-Activating Ligands

Adjuvant combinations may enhance or broaden the expression of immune responses to vaccine antigens. Information on whether established Alum type adjuvants can be combined with experimental CD1d ligand adjuvants is currently lacking. In this study, we used a murine Clostridioides difficile immunization and challenge model to evaluate Alum (Alhydrogel™), α-galactosylceramide (α-GC), and one of its analogs 7DW8-5 singly and in combination as vaccine adjuvants. We observed that the Alum/α-GC combination caused modest enhancement of vaccine antigen-specific IgG1 and IgG2b responses, and a broadening to include IgG2c that did not significantly impact overall protection. Similar observations were made using the Alum/7DW8-5 combination. Examination of the impact of adjuvants on NKT cells revealed expansion of invariant NKT (iNKT) cells with modest expansion of their iNKTfh subset and little effect on diverse NKT (dNKT) cells. Side effects of the adjuvants was determined and revealed transient hepatotoxicity when Alum/α-GC was used in combination but not singly. In summary these results showed that the Alum/α-GC or the Alum/7DW8-5 combination could exert distinct effects on the NKT cell compartment and on isotype switch to produce Th1-driven IgG subclasses in addition to Alum/Th2-driven subclasses. While Alum alone was efficacious in stimulating IgG-mediated protection, and α-GC offered no apparent additional benefit in the C. difficile challenge model, the work herein reveals immune response features that could be optimized and harnessed in other vaccine contexts.

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Identification of linear epitopes on the flagellar proteins of Clostridioides difficile

Scientific Reports ◽

10.1038/s41598-021-89488-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

A. Razim ◽

K. Pacyga ◽

P. Naporowski ◽

D. Martynowski ◽

A. Szuba ◽

...

Keyword(s):

Digestive Tract ◽

In Silico ◽

Anaerobic Bacterium ◽

Vaccine Antigen ◽

Protective Properties ◽

Clostridioides Difficile ◽

Vaccine Antigens ◽

Linear Epitopes ◽

Flagellar Proteins

AbstractClostridioides difficile (C. difficile) is an opportunistic anaerobic bacterium that causes severe diseases of the digestive tract of humans and animals. One of the possible methods of preventing C. difficile infection is to develop a vaccine. The most promising candidates for vaccine antigens are the proteins involved in the adhesion phenomena. Among them, the FliC and FliD are considered to be suitable candidates. In this paper, the FliC and FliD protein polypeptide epitopes were mapped in silico and by using PEPSCAN procedure. We identified four promising epitopes: 117QRMRTLS123, 205MSKAG209 of FliC and 226NKVAS230, 306TTKKPKD312 of FliD protein. We showed that 117QRMRTLS123 sequence is not only located in TLR5-binding and activating region, as previously shown, but forms an epitope recognized by C. difficile-infected patients’ antibodies. 205MSKAG209 is a C. difficile-unique, immunogenic sequence that forms an exposed epitope on the polymerized flagella structure which makes it a suitable vaccine antigen. 226NKVAS230 and 306TTKKPKD312 are well exposed and possess potential protective properties according to VaxiJen analysis. Our results open the possibility to use these epitopes as suitable anti-C. difficile vaccine antigens.

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Heteropentameric Cholera Toxin B Subunit Chimeric Molecules Genetically Fused to a Vaccine Antigen Induce Systemic and Mucosal Immune Responses: a Potential New Strategy To Target Recombinant Vaccine Antigens to Mucosal Immune Systems

Infection and Immunity ◽

10.1128/iai.73.9.5654-5665.2005 ◽

2005 ◽

Vol 73 (9) ◽

pp. 5654-5665 ◽

Cited By ~ 29

Author(s):

Tetsuya Harakuni ◽

Hideki Sugawa ◽

Ai Komesu ◽

Masayuki Tadano ◽

Takeshi Arakawa

Keyword(s):

Immune Responses ◽

Cholera Toxin ◽

Biologically Active ◽

Vaccine Antigen ◽

Cholera Toxin B Subunit ◽

Protein Fusion ◽

Immune Systems ◽

B Subunit ◽

Vaccine Antigens ◽

New Strategy

ABSTRACT Noninvasive mucosal vaccines are attractive alternatives to parenteral vaccines. Although the conjugation of vaccine antigens with the B subunit of cholera toxin (CTB) is one of the most promising strategies for vaccine delivery to mucosal immune systems, the molecule cannot tolerate large-protein fusion, as it severely impairs pentamerization and loses affinity for GM1-ganglioside. Here we report a new strategy, in which steric hindrance between CTB-antigen fusion subunits is significantly reduced through the integration of unfused CTB “molecular buffers” into the pentamer unit, making them more efficiently self-assemble into biologically active pentamers. In addition, the chimeric protein took a compact configuration, becoming small enough to be secreted, and one-step affinity-purified proteins, when administered through a mucosal route, induced specific immune responses in mice. Since our results are not dependent on the use of a particular expression system or vaccine antigen, this strategy could be broadly applicable to bacterial enterotoxin-based vaccine design.

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Structural and Biophysical Characterization of the HCV E1E2 Heterodimer for Vaccine Development

Viruses ◽

10.3390/v13061027 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1027

Author(s):

Eric A. Toth ◽

Andrezza Chagas ◽

Brian G. Pierce ◽

Thomas R. Fuerst

Keyword(s):

Immune Responses ◽

Vaccine Development ◽

Vaccine Antigen ◽

Effective Vaccine ◽

Biophysical Characterization ◽

Vaccine Candidates ◽

Glycoprotein Complex ◽

Vaccine Antigens ◽

Health Need

An effective vaccine for the hepatitis C virus (HCV) is a major unmet medical and public health need, and it requires an antigen that elicits immune responses to multiple key conserved epitopes. Decades of research have generated a number of vaccine candidates; based on these data and research through clinical development, a vaccine antigen based on the E1E2 glycoprotein complex appears to be the best choice. One bottleneck in the development of an E1E2-based vaccine is that the antigen is challenging to produce in large quantities and at high levels of purity and antigenic/functional integrity. This review describes the production and characterization of E1E2-based vaccine antigens, both membrane-associated and a novel secreted form of E1E2, with a particular emphasis on the major challenges facing the field and how those challenges can be addressed.

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Impact of influenza virus during pregnancy: from disease severity to vaccine efficacy

Future Virology ◽

10.2217/fvl-2020-0024 ◽

2020 ◽

Vol 15 (7) ◽

pp. 441-453

Author(s):

Ana Vazquez-Pagan ◽

Rebekah Honce ◽

Stacey Schultz-Cherry

Keyword(s):

Influenza Virus ◽

Virus Infection ◽

Immune Responses ◽

Pregnant Women ◽

Disease Severity ◽

Influenza A ◽

Antiviral Treatment ◽

Influenza Virus Infection ◽

Severe Influenza ◽

The Impact

Pregnant women are among the individuals at the highest risk for severe influenza virus infection. Infection of the mother during pregnancy increases the probability of adverse fetal outcomes such as small for gestational age, preterm birth and fetal death. Animal models of syngeneic and allogeneic mating can recapitulate the increased disease severity observed in pregnant women and are used to define the mechanism(s) of that increased severity. This review focuses on influenza A virus pathogenesis, the unique immunological landscape during pregnancy, the impact of maternal influenza virus infection on the fetus and the immune responses at the maternal–fetal interface. Finally, we summarize the importance of immunization and antiviral treatment in this population and highlight issues that warrant further investigation.

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Model-based evaluation of school- and non-school-related measures to control the COVID-19 pandemic

Nature Communications ◽

10.1038/s41467-021-21899-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Ganna Rozhnova ◽

Christiaan H. van Dorp ◽

Patricia Bruijning-Verhagen ◽

Martin C. J. Bootsma ◽

Janneke H. H. M. van de Wijgert ◽

...

Keyword(s):

Reproduction Number ◽

Additional Benefit ◽

Transmission Model ◽

Time Points ◽

School Based ◽

Admission Data ◽

Age Structured ◽

The Impact ◽

Pandemic Wave

AbstractThe role of school-based contacts in the epidemiology of SARS-CoV-2 is incompletely understood. We use an age-structured transmission model fitted to age-specific seroprevalence and hospital admission data to assess the effects of school-based measures at different time points during the COVID-19 pandemic in the Netherlands. Our analyses suggest that the impact of measures reducing school-based contacts depends on the remaining opportunities to reduce non-school-based contacts. If opportunities to reduce the effective reproduction number (Re) with non-school-based measures are exhausted or undesired and Re is still close to 1, the additional benefit of school-based measures may be considerable, particularly among older school children. As two examples, we demonstrate that keeping schools closed after the summer holidays in 2020, in the absence of other measures, would not have prevented the second pandemic wave in autumn 2020 but closing schools in November 2020 could have reduced Re below 1, with unchanged non-school-based contacts.

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Oxidative Stress Compromises Lymphocyte Function in Neonatal Dairy Calves

Antioxidants ◽

10.3390/antiox10020255 ◽

2021 ◽

Vol 10 (2) ◽

pp. 255

Author(s):

Wilmer Cuervo ◽

Lorraine M. Sordillo ◽

Angel Abuelo

Keyword(s):

Oxidative Stress ◽

Immune Responses ◽

Immune Cell ◽

Lymphocyte Activation ◽

Dairy Calves ◽

Lymphocyte Function ◽

Newborn Calves ◽

Ifn Γ ◽

The Impact

Dairy calves are unable to mount an effective immune response during their first weeks of life, which contributes to increased disease susceptibility during this period. Oxidative stress (OS) diminishes the immune cell capabilities of humans and adult cows, and dairy calves also experience OS during their first month of life. However, the impact that OS may have on neonatal calf immunity remains unexplored. Thus, we aimed to evaluate the impact of OS on newborn calf lymphocyte functions. For this, we conducted two experiments. First, we assessed the association of OS status throughout the first month of age and the circulating concentrations of the cytokines interferon-gamma (IFN-γ) and interleukin (IL) 4, as well as the expression of cytokine-encoding genes IFNG, IL2, IL4, and IL10 in peripheral mononuclear blood cells (PBMCs) of 12 calves. Subsequently, we isolated PBMCs from another 6 neonatal calves to investigate in vitro the effect of OS on immune responses in terms of activation of lymphocytes, cytokine expression, and antibody production following stimulation with phorbol 12-myristate 13-acetate or bovine herpesvirus-1. The results were compared statistically through mixed models. Calves exposed to high OS status in their first month of age showed higher concentrations of IL-4 and expression of IL4 and IL10 and lower concentrations of IFN-γ and expression of IFNG and IL2 than calves exposed to lower OS. In vitro, OS reduced lymphocyte activation, production of antibodies, and protein and gene expression of key cytokines. Collectively, our results demonstrate that OS can compromise some immune responses of newborn calves. Hence, further studies are needed to explore the mechanisms of how OS affects the different lymphocyte subsets and the potential of ameliorating OS in newborn calves as a strategy to augment the functional capacity of calf immune cells, as well as enhance calves’ resistance to infections.

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216. Are Automatic Antimicrobial Stop Orders an Effective Stewardship Tool for Urinary Tract and Intra-Abdominal Infections?

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.260 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S110-S110

Author(s):

Christina Maguire ◽

Dusten T Rose ◽

Theresa Jaso

Keyword(s):

Urinary Tract ◽

Antimicrobial Therapy ◽

Source Control ◽

Clostridioides Difficile ◽

Days Of Therapy ◽

Before And After ◽

The Difference ◽

Tract Infections ◽

Length Of Therapy ◽

The Impact

Abstract Background Automatic antimicrobial stop orders (ASOs) are a stewardship initiative used to decrease days of therapy, prevent resistance, and reduce drug costs. Limited evidence outside of the perioperative setting exists on the effects of ASOs on broad spectrum antimicrobial use, discharge prescription duration, and effects of missed doses. This study aims to evaluate the impact of an ASO policy across a health system of adult academic and community hospitals for treatment of intra-abdominal (IAI) and urinary tract infections (UTI). ASO Outcome Definitions ASO Outcomes Methods This multicenter retrospective cohort study compared patients with IAI and UTI treated before and after implementation of an ASO. Patients over the age of 18 with a diagnosis of UTI or IAI and 48 hours of intravenous (IV) antimicrobial administration were included. Patients unable to achieve IAI source control within 48 hours or those with a concomitant infection were excluded. The primary outcome was the difference in sum length of antimicrobial therapy (LOT). Secondary endpoints include length and days of antimicrobial therapy (DOT) at multiple timepoints, all cause in hospital mortality and readmission, and adverse events such as rates of Clostridioides difficile infection. Outcomes were also evaluated by type of infection, hospital site, and presence of infectious diseases (ID) pharmacist on site. Results This study included 119 patients in the pre-ASO group and 121 patients in the post-ASO group. ASO shortened sum length of therapy (LOT) (12 days vs 11 days respectively; p=0.0364) and sum DOT (15 days vs 12 days respectively; p=0.022). This finding appears to be driven by a decrease in outpatient LOT (p=0.0017) and outpatient DOT (p=0.0034). Conversely, ASO extended empiric IV LOT (p=0.005). All other secondary outcomes were not significant. Ten patients missed doses of antimicrobials due to ASO. Subgroup analyses suggested that one hospital may have influenced outcomes and reduction in LOT was observed primarily in sites without an ID pharmacist on site (p=0.018). Conclusion While implementation of ASO decreases sum length of inpatient and outpatient therapy, it may not influence inpatient length of therapy alone. Moreover, ASOs prolong use of empiric intravenous therapy. Hospitals without an ID pharmacist may benefit most from ASO protocols. Disclosures All Authors: No reported disclosures

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The Role of NKT Cells in Glioblastoma

Cells ◽

10.3390/cells10071641 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1641

Author(s):

Emily E. S. Brettschneider ◽

Masaki Terabe

Keyword(s):

Immune Responses ◽

Cell Activity ◽

Nkt Cells ◽

Type I ◽

Type Ii ◽

Central Nervous System Diseases ◽

Nkt Cell ◽

Lipid Antigens ◽

Immunoregulatory Mechanisms

Glioblastoma is an aggressive and deadly cancer, but to date, immunotherapies have failed to make significant strides in improving prognoses for glioblastoma patients. One of the current challenges to developing immunological interventions for glioblastoma is our incomplete understanding of the numerous immunoregulatory mechanisms at play in the glioblastoma tumor microenvironment. We propose that Natural Killer T (NKT) cells, which are unconventional T lymphocytes that recognize lipid antigens presented by CD1d molecules, may play a key immunoregulatory role in glioblastoma. For example, evidence suggests that the activation of type I NKT cells can facilitate anti-glioblastoma immune responses. On the other hand, type II NKT cells are known to play an immunosuppressive role in other cancers, as well as to cross-regulate type I NKT cell activity, although their specific role in glioblastoma remains largely unclear. This review provides a summary of our current understanding of NKT cells in the immunoregulation of glioblastoma as well as highlights the involvement of NKT cells in other cancers and central nervous system diseases.

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The Impact of Changing to an Algorithm-Based Clostridioides difficile Test on the Decision to Treat Clostridioides difficile

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2020.1058 ◽

2020 ◽

Vol 41 (S1) ◽

pp. s407-s407

Author(s):

Lana Dbeibo ◽

Joy Williams ◽

Josh Sadowski ◽

William Fadel ◽

Vera Winn ◽

...

Keyword(s):

Critical Care ◽

Toxic Megacolon ◽

Adverse Outcomes ◽

Clinical Criteria ◽

Testing Method ◽

Clostridioides Difficile ◽

Critical Care Admission ◽

The Impact ◽

Test Result ◽

Pcr Test

Background: Polymerase chain reaction (PCR) testing for the diagnosis of Clostridioides difficile infection (CDI) detects the presence of the organism; a positive result therefore cannot differentiate between colonization and the pathogenic presence of the bacterium. This may result in overdiagnosis, overtreatment, and risking disruption of microbial flora, which may perpetuate the CDI cycle. Algorithm-based testing offers an advantage over PCR testing as it detects toxin, which allows differentiation between colonization and infection. Although previous studies have demonstrated the clinical utility of this testing algorithm in differentiating infection from colonization, it is unknown whether the test changes CDI treatment decisions. Our facility switched from PCR to an algorithm-based testing method for CDI in June 2018. Objective: In this study, we evaluated whether clinicians’ decisions to treat patients are impacted by a test result that implies colonization (GDH+/Tox−/PCR+ test), and we examined the impact of this decision on patient outcomes. Methods: This is a retrospective cohort study of inpatients with a positive C. diff test between June 2017 and June 2019. The primary outcome was the proportion of patients treated for CDI. We compared this outcome in 3 groups of patients: those with a positive PCR test (June 2017–June 2018), those who had a GDH+/Tox−/PCR+ or a GDH+/Tox+ test result (June 2018–June 2019). Secondary outcomes included toxic megacolon, critical care admission, and mortality in patients with GDH+/Tox−/PCR+ who were treated versus those who were untreated. Results: Of patients with a positive PCR test, 86% were treated with CDI-specific antibiotics, whereas 70.4% with GDH+/Tox+ and 29.25% with GDH+/Tox−/PCR+ result were treated (P < .0001). Mortality was not different between patients with GDH+/Tox−/PCR+ who were treated versus those who were untreated (2.7% vs 3.4%; P = .12), neither was critical care admission within 2 or 7 days of test result (2% vs 1.4%; P = .15) and (4.1% vs 5.4%, P = .39), respectively. There were no cases of toxic megacolon during the study period. Conclusions: The change to an algorithm-based C. difficile testing method had a significant impact on the clinicians’ decisions to treat patients with a positive test, as most patients with a GDH+/Tox−/PCR+ result did not receive treatment. These patients did not suffer more adverse outcomes compared to those who were treated, which has implications for testing practices. It remains to be explored whether clinicians are using clinical criteria to decide whether or not to treat patients with a positive algorithm-based test, as opposed to the more reflexive treatment of patients with a positive PCR test.Funding: NoneDisclosures: None

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