scholarly journals Killed but Metabolically Active Leishmania infantum as a Novel Whole-Cell Vaccine for Visceral Leishmaniasis

2012 ◽  
Vol 19 (4) ◽  
pp. 490-498 ◽  
Author(s):  
Kevin W. Bruhn ◽  
Ron Birnbaum ◽  
Jacquelyn Haskell ◽  
Veena Vanchinathan ◽  
Stephanie Greger ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Leishmania Infantum ◽  
Parasitic Infection ◽  
Cell Vaccine ◽  
Vaccine Strategy ◽  
Whole Cell ◽  
Content Type ◽  
Whole Cell Vaccine

ABSTRACTThere are currently no effective vaccines for visceral leishmaniasis, the second most deadly parasitic infection in the world. Here, we describe a novel whole-cell vaccine approach usingLeishmania infantum chagasipromastigotes treated with the psoralen compound amotosalen (S-59) and low doses of UV A radiation. This treatment generates permanent, covalent DNA cross-links within parasites and results inLeishmaniaorganisms termed killed but metabolically active (KBMA). In this report, we characterize thein vitrogrowth characteristics of both KBMAL. majorand KBMAL. infantum chagasi. Concentrations of S-59 that generate optimally attenuated parasites were identified. Like liveL. infantum chagasi, KBMAL. infantum chagasiparasites were able to initially enter liver cellsin vivoafter intravenous infection. However, whereas liveL. infantum chagasiinfection leads to hepatosplenomegaly in mice after 6 months, KBMAL. infantum chagasiparasites were undetectable in the organs of mice at this time point.In vitro, KBMAL. infantum chagasiretained the ability to enter macrophages and induce nitric oxide production. These characteristics of KBMAL. infantum chagasicorrelated with the ability to prophylactically protect mice via subcutaneous vaccination at levels similar to vaccination with live, virulent organisms. Splenocytes from mice vaccinated with either liveL. infantum chagasior KBMAL. infantum chagasidisplayed similar cytokine patternsin vitro. These results suggest that KBMA technology is a potentially safe and effective novel vaccine strategy against the intracellular protozoanL. infantum chagasi. This approach may represent a new method for whole-cell vaccination against other complex intracellular pathogens.

scholarly journals Nanoliposomal Buparvaquone Immunomodulates Leishmania infantum-Infected Macrophages and Is Highly Effective in a Murine Model

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Thais Alves da Costa-Silva ◽  
Andrés Jimenez Galisteo ◽  
José Angelo Lauletta Lindoso ◽  
Leandro R. S. Barbosa ◽  
Andre Gustavo Tempone
Keyword(s):  
Visceral Leishmaniasis ◽  
Leishmania Infantum ◽  
Drug Repositioning ◽  
Interleukin 10 ◽  
Pcr Analysis ◽  
Hydrodynamic Diameter ◽  
Content Type ◽  
Highly Effective

ABSTRACT Visceral leishmaniasis is a fatal parasitic neglected disease affecting 1.5 million people worldwide. Based on a drug repositioning approach, the aim of this work was to investigate the in vitro immunomodulatory potential of buparvaquone (BPQ) and to establish a safe regimen to evaluate the in vivo efficacy of BPQ entrapped by negatively charged nanoliposomes (BPQ-LP) in Leishmania infantum-infected hamsters. Small-angle X-ray scattering, dynamic light scattering, and the ζ-potential were applied in order to study the influence of BPQ on the liposome structure. Our data revealed that BPQ was located in the polar-apolar interface, snorkeling the polar region, and protected against aggregation inside the lipophilic region. The presence of BPQ also decreased the Z-average hydrodynamic diameter and increased the surface charge. Compared to intravenous and intramuscular administration, a subcutaneous route was a more effective route for BPQ-LP; at 0.4 mg/kg, BPQ-LP reduced infection in the spleen and liver by 98 and 96%, respectively. Treatment for 5 days resulted in limited efficacy, but 10 days of treatment resulted in an efficacy similar to that of a 15-day regimen. The nanoliposomal drug was highly effective, with a mean 50% effective dose of 0.25 mg/kg, reducing the parasite load in bone marrow by 80%, as detected using quantitative PCR analysis. In addition, flow cytometry studies showed that BPQ upregulated cytokines as tumor necrosis factor, monocyte chemoattractant protein 1, interleukin-10 (IL-10), and IL-6 in Leishmania-infected macrophages, eliminating the parasites via a nitric oxide-independent mechanism. This new formulation proved to be a safe and effective treatment for murine leishmaniasis that could be a useful candidate against visceral leishmaniasis.

scholarly journals In VitroandIn VivoCharacterization of the Novel Oxabicyclooctane-Linked Bacterial Topoisomerase Inhibitor AM-8722, a Selective, Potent Inhibitor of Bacterial DNA Gyrase

2016 ◽  
Vol 60 (8) ◽  
pp. 4830-4839 ◽  
Author(s):  
Christopher M. Tan ◽  
Charles J. Gill ◽  
Jin Wu ◽  
Nathalie Toussaint ◽  
Jingjun Yin ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Antibacterial Agents ◽  
Cell Activity ◽  
Dna Gyrase ◽  
Topoisomerase Iv ◽  
Bacterial Dna ◽  
Whole Cell ◽  
Content Type

ABSTRACTOxabicyclooctane-linked novel bacterial topoisomerase inhibitors (NBTIs) represent a new class of recently described antibacterial agents with broad-spectrum activity. NBTIs dually inhibit the clinically validated bacterial targets DNA gyrase and topoisomerase IV and have been shown to bind distinctly from known classes of antibacterial agents directed against these targets. Herein we report the molecular, cellular, andin vivocharacterization of AM-8722 as a representative N-alkylated-1,5-naphthyridone left-hand-side-substituted NBTI. Consistent with its mode of action, macromolecular labeling studies revealed a specific effect of AM-8722 to dose dependently inhibit bacterial DNA synthesis. AM-8722 displayed greater intrinsic enzymatic potency than levofloxacin versus both DNA gyrase and topoisomerase IV fromStaphylococcus aureusandEscherichia coliand displayed selectivity against human topoisomerase II. AM-8722 was rapidly bactericidal and exhibited whole-cell activity versus a range of Gram-negative and Gram-positive organisms, with no whole-cell potency shift due to the presence of DNA or human serum. Frequency-of-resistance studies demonstrated an acceptable rate of resistance emergencein vitroat concentrations 16- to 32-fold the MIC. AM-8722 displayed acceptable pharmacokinetic properties and was shown to be efficacious in mouse models of bacterial septicemia. Overall, AM-8722 is a selective and potent NBTI that displays broad-spectrum antimicrobial activityin vitroandin vivo.

scholarly journals In vitro and in vivo resistance of Leishmania infantum to meglumine antimoniate: a study of 37 strains collected from patients with visceral leishmaniasis.

1997 ◽  
Vol 41 (4) ◽  
pp. 827-830 ◽  
Author(s):  
F Faraut-Gambarelli ◽  
R Piarroux ◽  
M Deniau ◽  
B Giusiano ◽  
P Marty ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Leishmania Infantum ◽  
Strongly Correlated ◽  
Duration Of Treatment ◽  
In Vitro Sensitivity ◽  
Sensitivity Tests ◽  
Leishmania Parasites ◽  
Immunocompetent Patients

Primary and secondary unresponsiveness to meglumine has long been described in human visceral leishmaniasis. However, no studies have been performed to elucidate if these therapeutic failures were due to strain variability in meglumine sensitivity or were related to host factors. We have studied the in vitro sensitivity of 37 strains of Leishmania infantum isolated from 23 patients (11 human immunodeficiency virus-infected and 12 immunocompetent patients) with visceral leishmaniasis. Sensitivity tests were performed by infecting murine macrophages with Leishmania parasites and culturing them in medium containing different concentrations of meglumine. For each test we calculated a 50% effective dose (ED50) corresponding to the meglumine concentration at which 50% of the Leishmania parasites survived. In vitro results were strongly correlated to immediate clinical outcome. All strains requiring an ED50 of >70 microg/ml were related to therapeutic failures, whereas all strains requiring an ED50 of <40 microg/ml corresponded to an initial efficiency of meglumine. Among those patients who were initially improved, relapses occurred in all immunocompromised patients and in most immunocompetent patients who had a short duration of treatment (15 days). Finally, we found that in vitro sensitivity of strains decreased progressively in relapsing patients treated with meglumine. Consequently, the physician may be encouraged to alternate meglumine with other treatments such as amphotericin B or pentamidine, especially in the case of relapsing patients.

scholarly journals A Self-Assembling Whole-Cell Vaccine Antigen Presentation Platform

2018 ◽  
Vol 200 (15) ◽  
Author(s):  
Julie Liao ◽  
Daniel R. Smith ◽  
Jóhanna Brynjarsdóttir ◽  
Paula I. Watnick
Keyword(s):  
Vibrio Cholerae ◽  
Bacterial Biofilm ◽  
Cell Vaccine ◽  
Secreted Protein ◽  
Proof Of Concept ◽  
Whole Cell ◽  
Content Type ◽  
Self Assembling ◽  
Whole Cell Vaccine ◽  
Common Infection

ABSTRACTDiarrhea is the most common infection in children under the age of 5 years worldwide. In spite of this, only a few vaccines to treat infectious diarrhea exist, and many of the available vaccines are sparingly and sporadically administered. Major obstacles to the development and widespread implementation of vaccination include the ease and cost of production, distribution, and delivery. Here we present a novel, customizable, and self-assembling vaccine platform that exploits theVibrio choleraebacterial biofilm matrix for antigen presentation. We use this technology to create a proof-of-concept, live-attenuated whole-cell vaccine that is boosted by spontaneous association of a secreted protein antigen with the cell surface. Sublingual administration of this live-attenuated vaccine to mice confers protection againstV. choleraechallenge and elicits the production of antigen-specific IgA in stool. The platform presented here enables the development of antigen-boosted vaccines that are simple to produce and deliver, addressing many of the obstacles to vaccination against diarrheal diseases. This may also serve as a paradigm for the development of broadly protective biofilm-based vaccines against other mucosal infections.IMPORTANCEDiarrheal disease is the most common infection afflicting children worldwide. In resource-poor settings, these infections are correlated with cognitive delay, stunted growth, and premature death. With the development of efficacious, affordable, and easily administered vaccines, such infections could be prevented. While a major focus of research on biofilms has been their elimination, here we harness the bacterial biofilm to create a customizable platform for cost-effective, whole-cell mucosal vaccines that self-incorporate secreted protein antigens. We use this platform to develop a sublingually administered live-attenuated prototype vaccine based onVibrio cholerae. This serves not only as a proof of concept for a multivalent vaccine against common bacterial enteric pathogens but also as a paradigm for vaccines utilizing other bacterial biofilms to target mucosal infections.

scholarly journals The effect of the antigen which elicits the bactericidal antibody and of the mouse-protective antiǵen on the growth of Bordetella pertussis in the mouse brain

1975 ◽  
Vol 74 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Jean M. Dolby ◽  
J. P. Ackers ◽  
D. E. Dolby
Keyword(s):  
Bordetella Pertussis ◽  
Protective Antigen ◽  
Passive Immunity ◽  
Cell Vaccine ◽  
Potency Assay ◽  
Whole Cell ◽  
Protective Antibody ◽  
Bactericidal Antibody

SUMMARYThe effect of antigens of Bordetella pertussis and their antibodies on brain infections by B. pertussis in mice are suppression of an infection immediately, so that the initial 90 % loss due to leakage from the brain is maintained or the numbers of bacteria are reduced even further, sometimes with complete sterilization particularly after a small lethal challenge of 10 LD 50 (mechanism 1), and a delayed antibacterial activity in vivo which does not begin until 3 days after challenge (mechanism 2). The first, immediate reaction is over in 2–3 days; the second is maintained from 3–4 days onwards, and results in elimination of the bacteria and protection of mice.The parts played in vivo in overcoming infection in these two ways by two antigens and their respective antibodies have been investigated. These antigens are a lipopolysaccharide capable of eliciting an antibody which is bactericidal in vitro in the presence of complement called the ‘bactericidal antigen’, and the mouse protective antigen.Considering first passive immunity, bactericidal antibody elicited by isolated antigen, and of high titre in vitro, is only very weakly active by mechanism (1) in vivo. Brains are seldom sterilized and mice not therefore protected. Antisera to whole cell vaccines whether they contain the ‘bactericidal antigen’ or not, or the protective antigen or not can more easily reduce infections by mechanism (1), eliminating small lethal challenges in some mice which are protected. A passive, intracerebrally protective antibody (PIPA) different from other known antibodies, has been postulated to account for this. Antisera to whole cell vaccine which is protective as denned in the potency assay, can, in additon to this, protect mice by mechanism (2) not only against 10 LD 50 but also 100 LD 50 challenge, and is the only antibody which can do this.These antibodies have been investigated by injecting them with the challenging organisms. The antibody effects described above are given by antisera stimulated by several injections and also by the concentrated serum immunoglobulins of once vaccinated mice. The antibody, which is bactericidal in vitro only, is in the 7 S globulin fraction of the serum of once vaccinated mice. The protective antibody capable of overcoming small and large challenges is in the 19 S and 11 S globulins. The antibody, PIPA, protecting against small lethal challenges only is in the fraction A2 containing mainly 11 S globulin.In active immunization experiments the suppression of infection which immediately follows intracerebral vaccination, but which only lasts 2–3 days (mechanism 1), is not dependent on either ‘bactericidal’ or protective antigens but on a component present in all our whole cell vaccines. Vaccines which also had protective antigen eliminated the remaining infection at 4–6 days after challenge by mechanism (2).As in passive immunity, only the protective antigen can completely overcome 100 LD 50. Suppression of a small, lethal, intracerebral infection given 14 days after intraperitoneal vaccination by mechanism (1) may however be correlated with protective antigen.

scholarly journals Toll-Like Receptor 9 Signaling in Dendritic Cells Regulates Neutrophil Recruitment to Inflammatory Foci following Leishmania infantum Infection

2015 ◽  
Vol 83 (12) ◽  
pp. 4604-4616 ◽  
Author(s):  
Laís Sacramento ◽  
Silvia C. Trevelin ◽  
Manuela S. Nascimento ◽  
Djalma S. Lima-Jùnior ◽  
Diego L. Costa ◽  
...  
Keyword(s):  
Leishmania Infantum ◽  
Critical Role ◽  
Costimulatory Molecule ◽  
Protozoan Parasite ◽  
Neutrophil Recruitment ◽  
Content Type ◽  
Target Organs ◽  
Myd88 Signaling

Leishmania infantumis a protozoan parasite that causes visceral leishmaniasis (VL). This infection triggers dendritic cell (DC) activation through the recognition of microbial products by Toll-like receptors (TLRs). Among the TLRs, TLR9 is required for DC activation by differentLeishmaniaspecies. We demonstrated that TLR9 is upregulatedin vitroandin vivoduring infection. We show that C57BL/6 mice deficient in TLR9 expression (TLR9−/−mice) are more susceptible to infection and display higher parasite numbers in the spleen and liver. The increased susceptibility of TLR9−/−mice was due to the impaired recruitment of neutrophils to the infection foci associated with reduced levels of neutrophil chemoattractants released by DCs in the target organs. Moreover, both Th1 and Th17 cells were also committed in TLR9−/−mice. TLR9-dependent neutrophil recruitment is mediated via the MyD88 signaling pathway but is TIR domain-containing adapter-inducing interferon beta (TRIF) independent. Furthermore,L. infantumfailed to activate both plasmacytoid and myeloid DCs from TLR9−/−mice, which presented reduced surface costimulatory molecule expression and chemokine release. Interestingly, neutrophil chemotaxis was affected bothin vitroandin vivowhen DCs were derived from TLR9−/−mice. Our results suggest that TLR9 plays a critical role in neutrophil recruitment during the protective response againstL. infantuminfection that could be associated with DC activation.

scholarly journals Nanotized Curcumin and Miltefosine, a Potential Combination for Treatment of Experimental Visceral Leishmaniasis

2016 ◽  
Vol 61 (3) ◽  
Author(s):  
Brajendra Tiwari ◽  
Richa Pahuja ◽  
Pradeep Kumar ◽  
Srikanta Kumar Rath ◽  
Kailash Chand Gupta ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Leishmania Donovani ◽  
Oral Drug ◽  
Hamster Model ◽  
Content Type ◽  
Leishmanicidal Activity ◽  
Traditional Indian Medicine ◽  
Indian Medicine

ABSTRACT Leishmaniasis chemotherapy remains very challenging due to high cost of the drug and its associated toxicity and drug resistance, which develops over a period of time. Combination therapies (CT) are now in use to treat many diseases, such as cancer and malaria, since it is more effective and affordable than monotherapy. CT are believed to represent a new explorable strategy for leishmaniasis, a neglected tropical disease caused by the obligate intracellular parasite Leishmania. In the present study, we investigated the effect of a combination of a traditional Indian medicine (ayurveda), a natural product curcumin and miltefosine, the only oral drug for visceral leishmaniasis (VL) using a Leishmania donovani-hamster model. We developed an oral nanoparticle-based formulation of curcumin. Nanoformulation of curcumin alone exhibited significant leishmanicidal activity both in vitro and in vivo. In combination with miltefosine, it exhibited a synergistic effect on both promastigotes and amastigotes under in vitro conditions. The combination of these two agents also demonstrated increased in vivo leishmanicidal activity accompanied by increased production of toxic reactive oxygen/nitrogen metabolites and enhanced phagocytic activity. The combination also exhibited increased lymphocyte proliferation. The present study thus establishes the possible use of nanocurcumin as an adjunct to antileishmanial chemotherapy.

scholarly journals Development and Preclinical Evaluation of a Trivalent, Formalin-Inactivated Shigella Whole-Cell Vaccine

2014 ◽  
Vol 21 (3) ◽  
pp. 366-382 ◽  
Author(s):  
R. W. Kaminski ◽  
M. Wu ◽  
K. R. Turbyfill ◽  
K. Clarkson ◽  
B. Tai ◽  
...  
Keyword(s):  
Shigella Flexneri ◽  
Cell Vaccine ◽  
Whole Cell ◽  
Content Type ◽  
Whole Cells ◽  
Whole Cell Vaccine ◽  
Specific Igg ◽  
Vaccine Approach ◽  
Humoral Responses ◽  
Different Doses

ABSTRACTStudies were undertaken to manufacture a multivalentShigellainactivated whole-cell vaccine that is safe, effective, and inexpensive. By using several formalin concentrations, temperatures, and incubation periods, an optimized set of inactivation conditions was established forShigella flexneri2a,S. sonnei, andS. flexneri3a to produce inactivated whole cells expressing a full repertoire of Ipa proteins and lipopolysaccharide (LPS). The inactivation conditions selected were treatment with 0.2% formalin (S. flexneri2a and 3a) or 0.6% formalin (S. sonnei) for 48 h at 25°C. Vaccine formulations prepared under different inactivation conditions, in different doses (10E5, 10E7, and 10E9 cells), and with or without the inclusion of double-mutant heat-labile toxin (dmLT) were evaluated in mice. Two intranasal immunizations with ≥10E7 inactivated whole cells resulted in high levels of anti-Invaplex and moderate levels of LPS-specific IgG and IgA in serum and in lung and intestinal wash samples. Addition of dmLT to the vaccine formulations did not significantly enhance humoral immunogenicity. Minimal humoral responses for IpaB, IpaC, or IpaD were detected after immunization with inactivated wholeShigellacells regardless of the vaccine inactivation conditions. In guinea pigs, monovalent formulations ofS. flexneri2a of 3a orS. sonneiconsisting of 10E8, 10E9, or 10E10 cells were protective in a keratoconjunctivitis assay. A trivalent formulation provided protection against all three serotypes (S. flexneri2a,P= 0.018;S. flexneri3a,P= 0.04;S. sonnei,P< 0.0001). The inactivatedShigellawhole-cell vaccine approach incorporates an uncomplicated manufacturing process that is compatible with multivalency and the future development of a broadly protectiveShigellavaccine.

scholarly journals Antileishmanial Efficacy and Pharmacokinetics of DB766-Azole Combinations

2017 ◽  
Vol 62 (1) ◽  
Author(s):  
April C. Joice ◽  
Sihyung Yang ◽  
Abdelbasset A. Farahat ◽  
Heidi Meeds ◽  
Mei Feng ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Leishmania Donovani ◽  
Treatment Strategies ◽  
Parasite Burden ◽  
Pharmacokinetic Analysis ◽  
Content Type ◽  
New Treatment ◽  
Almost All

ABSTRACT Given the limitations of current antileishmanial drugs and the utility of oral combination therapy for other infections, developing an oral combination against visceral leishmaniasis should be a high priority. In vitro combination studies with DB766 and antifungal azoles against intracellular Leishmania donovani showed that posaconazole and ketoconazole, but not fluconazole, enhanced DB766 potency. Pharmacokinetic analysis of DB766-azole combinations in uninfected Swiss Webster mice revealed that DB766 exposure was increased by higher posaconazole and ketoconazole doses, while DB766 decreased ketoconazole exposure. In L. donovani-infected BALB/c mice, DB766-posaconazole combinations given orally for 5 days were more effective than DB766 or posaconazole alone. For example, 81% ± 1% (means ± standard errors) inhibition of liver parasite burden was observed for 37.5 mg/kg of body weight DB766 plus 15 mg/kg posaconazole, while 37.5 mg/kg DB766 and 15 mg/kg posaconazole administered as monotherapy gave 40% ± 5% and 21% ± 3% inhibition, respectively. Combination index (CI) analysis indicated that synergy or moderate synergy was observed in six of nine combined dose groups, while the other three were nearly additive. Liver concentrations of DB766 and posaconazole increased in almost all combination groups compared to monotherapy groups, although many increases were not statistically significant. For DB766-ketoconazole combinations evaluated in this model, two were antagonistic, one displayed synergy, and one was nearly additive. These data indicate that the efficacy of DB766-posaconazole and DB766-ketoconazole combinations in vivo is influenced in part by the pharmacokinetics of the combination, and that the former combination deserves further consideration in developing new treatment strategies against visceral leishmaniasis.

scholarly journals Discovery of Safe and Orally Effective 4-Aminoquinaldine Analogues as Apoptotic Inducers with Activity against Experimental Visceral Leishmaniasis

2011 ◽  
Vol 56 (1) ◽  
pp. 432-445 ◽  
Author(s):  
Partha Palit ◽  
Abhijit Hazra ◽  
Arindam Maity ◽  
R. S. K. Vijayan ◽  
Prabu Manoharan ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Oral Delivery ◽  
Leishmania Donovani ◽  
Reactive Oxygen Species Generation ◽  
Oral Route ◽  
Apoptotic Pathway ◽  
Content Type ◽  
Lead Compounds

ABSTRACTNovel antileishmanials are urgently required to overcome emergence of drug resistance, cytotoxic effects, and difficulties in oral delivery. Toward this, we investigated a series of novel 4-aminoquinaldine derivatives, a new class of molecules, as potential antileishmanials. 4-Aminoquinaldine derivatives presented inhibitory effects onL. donovanipromastigotes and amastigotes (50% inhibitory concentration range, 0.94 to 127 μM). Of these, PP-9 and PP-10 were the most effectivein vitroand demonstrated strong efficaciesin vivothrough the intraperitoneal route. They were also found to be effective against both sodium antimony gluconate-sensitive and -resistantLeishmania donovanistrains in BALB/c mice when treated orally, resulting in more than 95% protection. Investigation of their mode of action revealed that killing by PP-10 involved moderate inhibition of dihydrofolate reductase and elicitation of the apoptotic cascade. Our studies implicate that PP-10 augments reactive oxygen species generation, evidenced from decreased glutathione levels and increased lipid peroxidation. Subsequent disruption ofLeishmaniapromastigote mitochondrial membrane potential and activation of cytosolic proteases initiated the apoptotic pathway, resulting in DNA fragmentation and parasite death. Our results demonstrate that PP-9 and PP-10 are promising lead compounds with the potential for treating visceral leishmaniasis (VL) through the oral route.

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