Live attenuated Leishmania major p27 gene knockout as a novel vaccine candidate: A study on safety, protective immunity and efficacy against canine leishmaniasis caused by Leishmania infantum

According to the World Health Organization, leishmaniasis remains a major worldwide public health problem. The province of Sefrou located in the center of Morocco is a focus of cutaneous leishmaniasis. The present study aims at evaluating the antileishmanial potential of Berberis sp.,Crataegus oxyacantha, Cistus salviifolius, Ephedra altissima and Lavandula dentatafrequently used by the local population. Methanolic extracts were tested against the promastigote form ofLeishmania tropica, Leishmania majorandLeishmania infantumusing tetrazolium-based colorimetric (MTT) assay. The total phenol and flavonoids content of all extracts were determined using the Folin–Ciocalteu reagent, aluminum chloride, and potassium acetate solutions respectively. The plant extracts exhibited antileishmanial activity with variability depending on the tested strain and the plant species compared to Glucantime® used as control (IC50 (the half maximal inhibitory concentration) > 1,000 μg/mL). The best inhibition was observed with Berberis sp., againstLeishmania major(IC50 = 394.40 ± 3.02 μg/ml), andEphedra altissima(reported for the first time) againstLeishmania infantum(IC50 = 490.84 ± 3.15 μg/mL).Leishmania tropicahas shown the same sensitivity behavior toward the five extracts (in average IC50 = 540 ± 11.20 μg/mL). The total phenolic content was higher forCrataegus oxyacanthaandCistus salviifolius(140.67 ± 3.17 μg eq Gallic Acid (GA)/ mg of Extract (E) and 133.83 ± 9.03 μg eq GA/mg of E respectively), while flavonoid was higher forCistus salviifoliusandLavandula dentata(57.92 ± 2.46 μg eq Quercetin (Que)/ mg of Extract (E) and 41.53 ± 1.74 μg eq Que/mg of E). All the tested extracts present some promising aspects that may cure cutaneous leishmaniasis in the center of Morocco; further bioguided assays are needed to isolate the fractions and the bioactive molecule.

Download Full-text

The Leishmania infantum Acidic Ribosomal Protein P0 Administered as a DNA Vaccine Confers Protective Immunity to Leishmania major Infection in BALB/c Mice

Infection and Immunity ◽

10.1128/iai.71.11.6562-6572.2003 ◽

2003 ◽

Vol 71 (11) ◽

pp. 6562-6572 ◽

Cited By ~ 42

Author(s):

Salvador Iborra ◽

Manuel Soto ◽

Javier Carrión ◽

Ana Nieto ◽

Edgar Fernández ◽

...

Keyword(s):

Ribosomal Protein ◽

Leishmania Infantum ◽

Leishmania Major ◽

Parasite Burden ◽

Immunological Response ◽

Humoral Response ◽

Ifn Γ ◽

Immunogenic Properties ◽

Ribosomal Protein P0 ◽

Acidic Ribosomal Protein

ABSTRACT In this study, we examined the immunogenic properties of the Leishmania infantum acidic ribosomal protein P0 (LiP0) in the BALB/c mouse model. The humoral and cellular responses induced by the administration of the LiP0 antigen, either as soluble recombinant LiP0 (rLiP0) or as a plasmid DNA formulation (pcDNA3-LiP0), were determined. Also, the immunological response associated with a prime-boost strategy, consisting of immunization with pcDNA3-LiP0 followed by a boost with rLiP0, was assayed. Immunization with rLiP0 induced a predominant Th2-like humoral response, but no anti-LiP0 antibodies were induced after immunization with pcDNA3-LiP0, whereas a strong humoral response consisting of a mixed immunoglobulin G2a (IgG2a)-IgG1 isotype profile was induced in mice immunized with the prime-boost regime. For all three immunization protocols, rLiP0-stimulated production of gamma interferon (IFN-γ) in both splenocytes and lymph node cells from immunized mice was observed. However, it was only when mice were immunized with pcDNA3-LiP0 that noticeable protection against L. major infection was achieved, as determined by both lesion development and parasite burden. Immunization of mice with LiP0-DNA primes both CD4+ and CD8+ T cells, which, with the L. major challenge, were boosted to produce significant levels of IL-12-dependent, antigen-specific IFN-γ. Taken together, these data indicate that genetic vaccination with LiP0 induces protective immunological effector mechanisms, yet the immunological response elicited by LiP0 is not sufficient to keep the infection from progressing.

Download Full-text

Vaccination with DNA Encoding the Immunodominant LACK Parasite Antigen Confers Protective Immunity to Mice Infected with Leishmania major

Journal of Experimental Medicine ◽

10.1084/jem.186.7.1137 ◽

1997 ◽

Vol 186 (7) ◽

pp. 1137-1147 ◽

Cited By ~ 255

Author(s):

Sanjay Gurunathan ◽

David L. Sacks ◽

Daniel R. Brown ◽

Steven L. Reiner ◽

Hughes Charest ◽

...

Keyword(s):

T Cells ◽

Cd8 T Cells ◽

Protective Immunity ◽

Leishmania Major ◽

Protective Efficacy ◽

Dna Vaccination ◽

Attractive Alternative ◽

Dna Immunization ◽

Dna Encoding ◽

Ifn Γ

To determine whether DNA immunization could elicit protective immunity to Leishmania major in susceptible BALB/c mice, cDNA for the cloned Leishmania antigen LACK was inserted into a euykaryotic expression vector downstream to the cytomegalovirus promoter. Susceptible BALB/c mice were then vaccinated subcutaneously with LACK DNA and challenged with L. major promastigotes. We compared the protective efficacy of LACK DNA vaccination with that of recombinant LACK protein in the presence or absence of recombinant interleukin (rIL)-12 protein. Protection induced by LACK DNA was similar to that achieved by LACK protein and rIL-12, but superior to LACK protein without rIL-12. The immunity conferred by LACK DNA was durable insofar as mice challenged 5 wk after vaccination were still protected, and the infection was controlled for at least 20 wk after challenge. In addition, the ability of mice to control infection at sites distant to the site of vaccination suggests that systemic protection was achieved by LACK DNA vaccination. The control of disease progression and parasitic burden in mice vaccinated with LACK DNA was associated with enhancement of antigen-specific interferon-γ (IFN-γ) production. Moreover, both the enhancement of IFN-γ production and the protective immune response induced by LACK DNA vaccination was IL-12 dependent. Unexpectedly, depletion of CD8+ T cells at the time of vaccination or infection also abolished the protective response induced by LACK DNA vaccination, suggesting a role for CD8+ T cells in DNA vaccine induced protection to L. major. Thus, DNA immunization may offer an attractive alternative vaccination strategy against intracellular pathogens, as compared with conventional vaccination with antigens combined with adjuvants.

Download Full-text

Comparisons of Mutants Lacking the Golgi UDP-Galactose or GDP-Mannose Transporters Establish that Phosphoglycans Are Important for Promastigote but Not Amastigote Virulence in Leishmania major

Infection and Immunity ◽

10.1128/iai.00735-07 ◽

2007 ◽

Vol 75 (9) ◽

pp. 4629-4637 ◽

Cited By ~ 36

Author(s):

Althea A. Capul ◽

Suzanne Hickerson ◽

Tamara Barron ◽

Salvatore J. Turco ◽

Stephen M. Beverley

Keyword(s):

Golgi Apparatus ◽

Protective Immunity ◽

Leishmania Major ◽

Protozoan Parasite ◽

Macrophage Infection ◽

Nucleotide Sugar ◽

Infectious Cycle ◽

Null Mutants

ABSTRACT Abundant surface Leishmania phosphoglycans (PGs) containing [Gal(β1,4)Man(α1-PO4)]-derived repeating units are important at several points in the infectious cycle of this protozoan parasite. PG synthesis requires transport of activated nucleotide-sugar precursors from the cytoplasm to the Golgi apparatus. Correspondingly, null mutants of the L. major GDP-mannose transporter LPG2 lack PGs and are severely compromised in macrophage survival and induction of acute pathology in susceptible mice, yet they are able to persist indefinitely and induce protective immunity. However, lpg2 − L. mexicana amastigotes similarly lacking PGs but otherwise normal in known glycoconjugates remain able to induce acute pathology. To explore this further, we tested the infectivity of a new PG-null L. major mutant, which is inactivated in the two UDP-galactose transporter genes LPG5A and LPG5B. Surprisingly this mutant did not recapitulate the phenotype of L. major lpg2 −, instead resembling the L. major lipophosphoglycan-deficient lpg1 − mutant. Metacyclic lpg5A −/lpg5B − promastigotes showed strong defects in the initial steps of macrophage infection and survival. However, after a modest delay, the lpg5A − /lpg5B − mutant induced lesion pathology in infected mice, which thereafter progressed normally. Amastigotes recovered from these lesions were fully infective in mice and in macrophages despite the continued absence of PGs. This suggests that another LPG2-dependent metabolite is responsible for the L. major amastigote virulence defect, although further studies ruled out cytoplasmic mannans. These data thus resolve the distinct phenotypes seen among lpg2 − Leishmania species by emphasizing the role of glycoconjugates other than PGs in amastigote virulence, while providing further support for the role of PGs in metacyclic promastigote virulence.

Download Full-text