Antibiotic resistance free plasmid DNA expressing LACK protein leads towards a protective Th1 response against Leishmania infantum infection

Canine visceral leishmaniasis is a serious public health concern in the Mediterranean basin since dogs are the main Leishmania infantum reservoir. However, there is not a vaccination method in veterinary use in this area, and therefore the development of a vaccine against this parasite is essential for the possible control of the disease. Previous reports have shown the efficacy of heterologous prime-boost vaccination with the pCIneo plasmid and the poxvirus VV (both Western Reserve and MVA strains) expressing L. infantum LACK antigen against canine leishmaniasis. As pCIneo-LACK plasmid contains antibiotic resistance genes, its use as a profilactic method is not recommended. Hence, the antibiotic resistance gene free pORT-LACK plasmid is a more suitable tool for its use as a vaccine. Here we report the protective and immunostimulatory effect of the prime-boost pORT-LACK/MVA-LACK vaccination tested in a canine experimental model. Vaccination induced a reduction in clinical signs and in parasite burden in the liver, an induction of the Leishmania-specific T cell activation, as well as an increase of the expression of Th1 type cytokines in PBMC and target organs.     

Causes of Pediatric Visceral Leishmaniasis in Southeastern Iran

Leishmania infantum is the most frequent cause of visceral leishmaniasis and L. tropica has been rarely linked to the disease in Iran. In this study, bone marrow aspirates were collected from 10 child patients, suspected with visceral leishmaniasis referred to the Pediatric Wards of Kerman Medical Hospitals, Kerman, Iran during 2002–2011. Leishmania species were identified by using nested PCR in all slides. The PCR samples from nine patients indicated L. infantum as principal causative agent of visceral leishmaniasis and one L.tropica as a minor species.     

Immunization with the Leishmania infantum recombinant cyclophilin protein 1 confers partial protection to subsequent parasite infection and generates specific memory T cells

Control of zoonotic visceral leishmaniosis can be achieved using several available drugs. These drugs present high toxicity and require longer treatment regimens which complicate compliance to the treatment. Other control measures directed to the vector or the reservoirs are useful tools to restrain the spreading of this disease but the effects are transitory. A safe, affordable and efficient vaccine conferring long lasting immunity should be the most cost effective way of controlling zoonotic visceral leishmaniosis. The present study aims at characterizing a cyclophilin protein 1 of Leishmania infantum (LiCyP1) and investigating whether recombinant LiCyP1 (LirCyP1) is able to confer protection against infection by evaluating viable parasite load and the generation of specific CD4⁺ and CD8⁺ effector and central memory T cells in rodent model. LiCyP1 is present in the cytoplasm of L. infantum amastigotes and promastigotes. Immunization of BALB/c mice with LirCyP1 confers high protection to L. infantum infection, causing a marked reduction in parasite replication in the liver and spleen. Furthermore, helper and cytotoxic memory T cell subsets able to specifically recognize parasite antigens expanded in immunized and in challenged mice. CD4⁺ T cell subpopulation of intermediate phenotype (CD62L^highCD127^low) of challenging mice also presented an accentuated expansion after the recall. This study demonstrated that LirCyP1 confers partial protection to L. infantum infection, promoting the generation of a desired long lasting immunity. LirCyP1 can be considered a potential candidate for the design of a vaccine against zoonotic visceral leishmaniosis.     

Intranasal delivery of naked DNA encoding the LACK antigen leads to protective immunity against visceral leishmaniasis in mice

We previously showed that intranasal (i.n.) vaccination with pCIneo plasmid encoding the leishmanial LACK gene (pCIneo-LACK) induces long-lasting protective immunity against cutaneous leishmaniasis in mice. In this work, we proposed to investigate whether the efficacy of i.n. pCIneo-LACK is extensive to visceral leishmaniasis. BALB/c mice received two i.n. doses of 30 microg pCIneo-LACK prior to intravenous (i.v.) infection with Leishmania chagasi. Vaccinated mice developed significantly lower parasite burden in the liver and spleen than control mice receiving empty pCIneo or saline. The spleen cells of vaccinated mice produced significantly increased IFN-gamma and IL-4 concomitant with decreased IL-10 production during infection. Serum levels of specific IgG were elevated whereas TNF-alpha were decreased as compared with controls. These results show that the practical needle-free i.n. pCIneo-LACK vaccine displays potential broad-spectrum activity against leishmaniasis.     

Induction of immunogenicity by live attenuated Leishmania donovani centrin deleted parasites in dogs

Zoonotic visceral leishmaniasis, caused by the intracellular protozoan parasite Leishmania infantum, is a neglected tropical disease that is often fatal when untreated. Dogs are considered the main reservoir of L. infantum in zoonotic VL as the presence of infected dogs may increase the risk for human infection. Canine visceral leishmaniasis (CVL) is a major veterinary and public health problem in Southern Europe, Middle East and South America. Control of animal reservoirs relies on elimination of seropositive dogs in endemic areas. However, treatment of infected dogs is not considered a favorable approach as this can lead to emergence of drug resistance since the same drugs are used to treat human infections. Therefore, vaccination against CVL remains the best alternative in control of the animal reservoirs. In this study, we present data on the immunogenicity profile of a live attenuated parasite LdCen^−/− in a canine infection model and compared it to that of Leishmune^®, a commercially available recombinant vaccine. The immunogenicity of the LdCen^−/− parasites was evaluated by antibody secretion, production of intracytoplasmic and secreted cytokines, activation and proliferation of T cells. Vaccination with LdCen^−/− resulted in high immunogenicity as revealed by the higher IgGTotal, IgG1, and IgG2 production and higher lymphoproliferative response. Further, LdCen^−/− vaccinated dogs showed higher frequencies of activated CD4+ and CD8+ T cells, IFN-γ production by CD8+ T cells, increased secretion of TNF-α and IL-12/IL-23p40 and decreased secretion of IL-4. These results contribute to the understanding of immunogenicity elicited by live attenuated L. donovani parasites and, consequently, to the development of effective vaccines against visceral leishmaniasis.     

Leishmania infantum sterol 24-c-methyltransferase formulated with MPL-SE induces cross-protection against L. major infection

The enzyme sterol 24-c-methyltranferase (SMT) is required for the biosynthesis of ergosterol, the major membrane sterol in Leishmania parasites. SMT and ergosterol are not found in mammals, so this protein may be an attractive target for anti-leishmanial vaccines and drugs. We have previously demonstrated that SMT from L. infantum, which causes visceral leishmaniasis, is a protective antigen against this parasite. Because this protein is highly conserved among Leishmania species, we evaluated the potential of SMT to cross-protect against a different form of leishmaniasis. Here, we show that immunization with L. infantum SMT, formulated with monophosphoryl lipid A in stable emulsion (MPL-SE), protects mice from cutaneous leishmaniasis caused by L. major. In BALB/c mice the vaccine preparation induced antigen-specific multi-functional CD4⁺ T cells capable of producing IFN-γ, IL-2, and/or TNF-α upon antigen re-exposure, and MPL-SE was indispensable to direct immune responses to SMT towards Th1. Mice immunized with the SMT/MPL-SE vaccine developed significantly smaller lesions following ear challenge with L. major. These results suggest that SMT is a promising vaccine antigen for multiple forms of leishmaniasis.     

The characterization by isoenzyme electrophoresis of Leishmania isolated in the People's Republic of China

Seven isolates of Leishmania from mainland China were characterized on the basis of their isoenzyme profiles for 10 enzymes. Five isolates were from human visceral leishmaniasis patients, and four of these showed isoenzyme patterns similar to the marker strain of Leishmania infantum, while one was similar to L. donovani sensu lato. One isolate was from a presumed reservoir host of human visceral leishmaniasis, the racoon dog Nyctereutes procyanoides, and was isoenzymically indistinguishable from L. infantum. An isolate of L. gerbilli from the great gerbil Rhombomys opimus was readily distinguishable from Old World marker strains and other Chinese leishmanias. This is the first report of the biochemical characterization of Chinese isolates of Leishmania.     

Recombinant Leishmania tarentolae expressing the A2 virulence gene as a novel candidate vaccine against visceral leishmaniasis

Visceral leishmaniasis is the most severe form of leishmaniasis. To date, there is no effective vaccine against this disease. Many antigens have been examined so far as protein- or DNA-based vaccines, but none of them conferred complete long-term protection. The use of live attenuated vaccines has recently emerged as a promising vaccination strategy. In this study, we stably expressed the Leishmania donovani A2 antigen in Leishmania tarentolae, a non-pathogenic member of the genus Leishmania, and evaluated its protective efficacy as a live vaccine against L. infantum challenge. Our results show that a single intraperitoneal administration of the A2-recombinant L. tarentolae strain protects BALB/c mice against L. infantum challenge and that protective immunity is associated with high levels of IFN-γ production prior and after challenge. This is accompanied by reduced levels of IL-5 production after challenge, leading to a potent Th1 immune response. In contrast, intravenous injection elicited a Th2 type response, characterized by higher levels of IL-5 and high humoral immune response, resulting in a less efficient protection. All together, these results indicate the promise of A2-expressing L. tarentolae as a safe live vaccine against visceral leishmaniasis.     

Leishmania major p27 gene knockout as a novel live attenuated vaccine candidate: Protective immunity and efficacy evaluation against cutaneous and visceral leishmaniasis in BALB/c mice

Leishmaniasis is a growing health problem in many parts of the world and efforts to find vaccine against the disease are a public health priority. Live attenuated vaccines are the gold standard for protection against intracellular pathogens such as Leishmania spp. Defined genetic alteration of the Leishmania genome can be achieved using a gene-targeted disruption strategy that allows for the selection of parasites lacking genes essential for long-term survival and virulence. Previously, we demonstrated that genetically modified live attenuated Leishmania major, lacking the p27gene (Lmp27^−/−) is safe and induces cellular immunity in BALB/c mice. p27 is a component of the COX complex that is responsible for ATP synthesis. In the current study, the Lmp27^−/− strain was assessed as a live attenuated vaccine. Overall protective immunity and efficacy were evaluated at various time periods following Leishmania major (L. major) and Leishmania infantum (L. infantum) challenges separately in BALB/c mice. Cytokine and anti-Leishmania antibody levels, splenocyte proliferation, delayed type hypersensitivity (DTH), skin lesion development, and parasite burden in the liver and spleen were the measured variables. The results demonstrated that immunized mice had a significant T-helper type 1 (Th1) response, smaller skin lesions and lower parasite burdens in their liver and spleens following a L. major challenge. Furthermore, the Lmp27^−/− mutant also granted cross-protection against L. infantum infection.These results suggest that immunization with Lmp27^−/− parasites provide significant protective immunity and efficacy against infection with homologous as well as heterologous species of Leishmania parasites.     

Seroprevalence of Leishmania infantum in a rural area of Senegal: analysis of risk factors involved in transmission to humans

Whereas Leishmania infantum, the agent of visceral leishmaniasis (VL), is well known in North Africa, very limited data exist on its spread in West Africa, where mainly cutaneous leishmaniasis has been widely reported. Nevertheless, dogs infected with L. infantum were recently found in the Mont Rolland District in Senegal. To provide a better understanding of L. infantum epidemiology in this area, clinical and serological surveys were carried out to determine the seroprevalence of L. infantum-specific antibodies in the human population. In parallel, an analysis of environmental and individual factors associated with Leishmania antigen seropositivity was conducted to identify potential risk factors for exposure. Although no cases of VL were detected within this study, a large part of the population (73/315; 23%) was exposed to infection, with a strong age effect (being >40 years old increased the risk of being seropositive). Moreover, the presence of Nebedaye trees (Moringa oleifera) and infected dogs in the household were factors increasing the risk of exposure in household members. These results may provide important information to identify the still unknown sandfly species involved in transmission.     

Leishmanization revisited: Immunization with a naturally attenuated cutaneous Leishmania donovani isolate from Sri Lanka protects against visceral leishmaniasis

Leishmaniasis is a neglected tropical disease caused by Leishmania protozoa and associated with three main clinical presentations: cutaneous, mucocutaneous and visceral leishmaniasis. Visceral leishmaniasis is the second most lethal parasitic disease after malaria and there is so far no human vaccine. Leishmania donovani is a causative agent of visceral leishmaniasis in South East Asia and Eastern Africa. However, in Sri Lanka, L. donovani causes mainly cutaneous leishmaniasis, while visceral leishmaniasis is rare. We investigate here the possibility that the cutaneous form of L. donovani can provide immunological protection against the visceral form of the disease, as a potential explanation for why visceral leishmaniasis is rare in Sri Lanka. Subcutaneous immunization with a cutaneous clinical isolate from Sri Lanka was significantly protective against visceral leishmaniasis in BALB/c mice. Protection was associated with a mixed Th1/Th2 response. These results provide a possible rationale for the scarcity of visceral leishmaniasis in Sri Lanka and could guide leishmaniasis vaccine development efforts.     

Canine Visceral Leishmaniasis in Kerman,Southeast of Iran: A Seroepidemiological,Histopathological and Molecular Study

Background

Canine visceral leishmaniasis (CVL) is a systemic disease with a high mortality rate, caused by a diphasic protozoan parasite, Leishmania infantum/chagasi in the world. The objective of the present study was to determine the presence of CVL in the city and suburbs of Kerman, using a range of serological, histopathological and molecular methods.

Methods

Blood samples were taken from 80 clinically symptomatic stray dogs All the collected blood samples were tested by direct agglutination test (DAT) to detect the anti-Leishmania antibodies in dogs, using a cut-off value of ≥1:320. Pathological specimens including spleen, liver and lymph nodes were prepared for paraffin blocks, sectioning, staining and final microscopic examination in the pathology laboratory. PCR amplification of kDNA from 9 samples of DAT positive stray dogs was studied.

Results

The anti-Leishmania antibody was detected in 9 dogs (11.25 %) of the total 80 studied dogs. No significant difference was found between VL infection and gender. In contrast, there was a significant difference between seropositivity and age (P<0.05). Pathological samples showed changes including hyperplasia of infected macrophages and inflammatory cells that occupied sinusoids and splenic cords. Among the samples which was characterized by PCR, only one specimen revealed to be mixed infection between L. infantum and L. tropica.

Conclusion

The results revealed a high prevalence of L. infantum infection in stray dogs in Kerman. This kind of information is needed for implementation of future control programs.     

Cellular vaccination with bone marrow-derived dendritic cells pulsed with a peptide of Leishmania infantum KMP-11 and CpG oligonucleotides induces protection in a murine model of visceral leishmaniasis

The use of dendritic cells (DCs) pulsed with defined Leishmania antigens could be a potential immune intervention tool for the induction of protection against infection. In the present study, bone marrow-derived DCs (BM-DCs) pulsed ex vivo with the peptide 12-31aa portion of kinetoplastid membrane protein (KMP)-11 (KMP-11_12-31aa peptide) acquired a semimature phenotype expressing IL-12 and IL-10, whereas pulsing with the combination of the peptide and CpG oligodeoxynucleotides (ODNs) resulted in their functional maturation expressing mainly IL-12. Vaccination of genetically susceptible to parasite BALB/c mice with both peptide-pulsed BM-DCs elicited a peptide-specific mixed Th1/Th2 immune response, characterized by the production of IFNγ, IL-10 and IgG1 and IgG2a isotype antibodies. However, only BM-DCs pulsed with the combination of KMP-11_12-31aa peptide and CpG ODNs induced the differentiation of peptide-specific Th17 cells, indicating the adjuvanticity of CpG ODNs. When BALB/c mice were vaccinated with KMP-11_12-31aa peptide-pulsed BM-DCs, they exhibited only partial protection against Leishmania infantum challenge, whereas (KMP-11_12-31aa peptide + CpG ODNs)-pulsed BM-DCs reduced efficiently the parasite load in visceral organs. Protective immunity was correlated with restoration of lymphoproliferative responses and a modulation of parasite-specific cellular responses towards Th1 and Th17 profile, confirmed by the isotype switching towards IgG2a, the enhanced production of IFNγ against IL-10, the absence of TGF-β and the overproduction of IL-17. Thus, ex vivo antigen-pulsed BM-DCs represent a powerful tool for the study of protective immune responses against leishmanial infection. Moreover, these findings suggest the use of BM-DCs as effective tools in antigen and adjuvant screening in the design of a protective vaccine against leishmaniasis and other pathogen-related infections.     

Reduced pathogenicity of fructose-1,6-bisphosphatase deficient Leishmania donovani and its use as an attenuated strain to induce protective immunogenicity

Currently, there is no approved vaccine for visceral leishmaniasis (VL) caused by L. donovani. The ability to manipulate Leishmania genome by eliminating or introducing genes necessary for parasites’ survival considered as the powerful strategy to generate the live attenuated vaccine. In the present study fructose-1,6-bisphosphatase (LdFBPase) gene deleted L. donovani (Δfbpase) was generated using homologous gene replacement strategy. Though LdFBPase gene deletion (Δfbpase) does not affect the growth of parasite in the promastigote form but axenic amastigotes display a marked reduction in their capacity to multiply in vitro inside macrophages and in vivo in Balb/c mice. Though Δfbpase L. donovani parasite persisted in BALB/c mice up to 12 weeks but was unable to cause infection, we tested its ability to protect against a virulent L. donovani challenge. Notably, intraperitoneal immunisation with live Δfbpase parasites displayed the reduction of parasites load in mice spleen and liver post challenge. Moreover, immunised BALB/c mice showed a reversal of T cell anergy and high levels of NO production that result in the killing of the parasite. A significant, correlation was found between parasite clearance and elevated IFNγ, IL12, and IFNγ/IL10 ratio compared to IL10 and TGFβ in immunised and challenged mice. Results suggested the generation of protective Th1 type immune response which induced significant parasite clearance at 12-week, as well as 16 weeks post, challenged immunised mice, signifying sustained immunity. Therefore, we propose that Δfbpase L. donovani parasites can be a live attenuated vaccine candidate for VL and a good model to understand the correlatives of protection in visceral leishmaniasis.     

Spatial distribution and population genetics of Leishmania infantum genotypes in São Paulo State,Brazil, employing multilocus microsatellite typing directly in dog infected tissues

This study investigated the genetic characteristics of Leishmania infantum samples from São Paulo (SP) State, Brazil in order to collaborate with information about the possible origins of the parasites, as well as, the introduction and spread of visceral leishmaniasis in this Brazilian State. Multilocus microsatellite typing (MLMT) was performed using a set of 17 microsatellite markers. DNA was extracted from 250 samples collected from dogs diagnosed with visceral leishmaniasis and 112 (45%) were genotyped: 67 from the northwest region (NWSP), and 29 from the southeast region (SESP) of SP. The results were correlated with other 16 samples from Mato Grosso do Sul State (MS) (which borders NWSP). Although, a small portion of samples was genotyped, it was possible to genotype multiple loci using small amounts of Leishmania DNA extracted directly from dog tissues. Despite the fact that MLMT analysis defined 33 different genotypes, a low polymorphism was detected within the parasites studied with 10 polymorphic loci. There are two main genetic clusters circulating in SP with strong genetic differentiation, one (POP-A) is composed by samples from SESP and NWSP and presented a weak signal of geographical substructure. The other, belongs to the same cluster found in the state of MS (POP-B), which was the main one. The majority (93.75%) of MS parasite genotypes belonged to POP-B, with just one sample (6.25%) grouped in POP-A. POP-B also comprised 10.34% of SESP and 26.87% of NWSP samples. Besides one sample from MS, POP-A is composed by 73.13% of NWSP and 89.66% of SESP samples. The MLMT analysis supported the idea of canine visceral leishmaniasis being introduced in the Northwest region of SP State by the traffic of humans and dogs from MS. In the southeast region of SP occurred an introduction of a new L. infantum genetic cluster. Probably the transmission was spread by traffic of infected dogs from other Brazilian regions, or by introduction of imported dogs from other countries. All these data together contributed to the detection of the genetic profile of L. infantum population in SP State.     

Molecular and Seroepidemiological Survey of Visceral Leishmaniasis among Humans and Domestic Dogs in Mazandaran Province,North of Iran

Background

New cases of visceral leishmaniasis (VL) have been reported recently in some parts of Mazandaran Province, north of Iran where the first human case of VL was reported in 1949. This study aimed to determine the present status of Leishmania infantum infection among humans and domestic dogs using serological and molecular methods in central parts of Mazandaran Province.

Methods

In this cross-sectional study, blood samples were randomly collected from 402 humans and forty-nine domestic dogs throughout 2009 and 2010 in the central part of Mazandaran Province including Semeskadeh and Kiakola districts where recent cases of human visceral leishmaniasis had been reported there. All the collected samples were tested by direct agglutination test (DAT) for the detection of anti-Leishmania infantum antibodies as well as convenience PCR assay on whole blood samples for detection of leishmanial infection and identification of Leishmania species.

Results

None of 402 collected human (402) and dog (49) blood samples showed anti Leishmania infantum antibodies at titers 1:3200 and 1:320 as cut-off values of DAT, respectively but only 2 of domestic dogs (4.1%) were found PCR-positive corresponding to L.infantum.

Conclusion

This study confirms the circulation of L. infantum at least among domestic dogs and highlights the sporadic pattern of VL in the studied areas. Further investigations regarding to sand flies fauna and wild canines as reservoir hosts of the disease, are recommended.     

Identification and phylogenetic relationship of Iranian strains of various Leishmania species isolated from cutaneous and visceral cases of leishmaniasis based on N-acetylglucosamine-1-phosphate transferase gene

The identity of Iranian Leishmania species has been resolved to some extent by some genetic markers. In this study, based on N-acetylglucosamine-1-phosphate transferase (nagt) gene, we further elucidated the identity and phylogeny of the prevalent species in this country. DNAs of 121 isolates belonging to cutaneous leishmaniasis (CL) patients, canine visceral leishmaniasis (CVL) cases, and Rhombomys opimus rodents were amplified by targeting a partial sequence of nagt gene. All the amplicons were analyzed with restriction fragment length polymorphism (RFLP) using Acc1 enzyme, and 49 amplicons representing different reservoir hosts were sequenced and aligned with similar sequences from GenBank database. The RFLP analysis revealed that 41 CL patients were infected Leishmania tropica and 36 with Leishmania major. Among 10 CVL isolates, 6 were identified as Leishmania infantum and 4 as L. tropica. Amongst 34 rodents’ isolates, 11 and 23 isolates exhibited patterns similar to those of L. major, and L. tropica/Leishmania turanica, respectively. The sequencing results from all CL patients, CVL cases, and 4 reservoir rodents were in agreement with RFLP analysis and showed 99–100% homologies with the registered species of L. major, L. tropica, and L. infantum from Turkey, Tunisia, Iraq and Israel. Of the 7 rodent isolates exhibiting RFLP patterns similar to L. tropica/L. turanica, 3 exhibited the highest homologies (99–100%) with L. turanica and 4 with Leishmania gerbilli. The 49 nagt DNA sequences were grouped into five clusters representing L. major, L. tropica, L. infantum, L. turanica and L. gerbilli species, encompassing 19 haplotypes. No correlation was observed between intraspecies divergence and geographic distribution of haplotypes. The L. tropica haplotypes exhibited more homologies with those of L. infantum than L. major (97.2% vs. 96.9%), a probable indication to the potential ability of L. tropica to visceralize. Characterization of Iranian Leishmania isolates using nagt gene allowed unambiguous identification of five prevalent species with a high-resolution phylogeny.     

Vectorborne Transmission of Leishmania infantum from Hounds,United States

Leishmaniasis is a zoonotic disease caused by predominantly vectorborne Leishmania spp. In the United States, canine visceral leishmaniasis is common among hounds, and L. infantum vertical transmission among hounds has been confirmed. We found that L. infantum from hounds remains infective in sandflies, underscoring the risk for human exposure by vectorborne transmission.     

Development of chimeric protein as a multivalent vaccine for human Kinetoplastid infections: Chagas disease and leishmaniasis

Leishmania spp. and Trypanosoma cruzi are parasitic kinetoplastids of great medical and epidemiological importance since they are responsible for thousands of deaths and disability-adjusted life-years annually, especially in low- and middle-income countries. Despite efforts to minimize their impact, current prevention measures have failed to fully control their spread. There are still no vaccines available. Taking into account the genetic similarity within the Class Kinetoplastida, we selected CD8⁺ T cell epitopes preserved among Leishmania spp. and T. cruzi to construct a multivalent and broad-spectrum chimeric polyprotein vaccine. In addition to inducing specific IgG production, immunization with the vaccine was able to significantly reduce parasite burden in the colon, liver and skin lesions from T. cruzi, L. infantum and L. mexicana challenged mice, respectively. These findings were supported by histopathological analysis, which revealed decreased inflammation in the colon, a reduced number of degenerated hepatocytes and an increased proliferation of connective tissue in the skin lesions of the corresponding T. cruzi, L. infantum and L. mexicana vaccinated and challenged mice. Collectively, our results support the protective effect of a polyprotein vaccine approach and further studies will elucidate the immune profile associated with this protection. Noteworthy, our results act as conceptual proof that a single multi-kinetoplastida vaccine can be used effectively to control different infectious etiologies, which in turn can have a profound impact on the development of a new generation of vaccines.     

Immunotherapy Using Autoclaved L. major Antigens and M. vaccae with Meglumine Antimoniate,for the Treatment of Experimental Canine Visceral Leishmaniasis

Background

To evaluate immunotherapy against canine visceral leishmaniasis, Leishmania major antigen and heat-killed Mycobacterium vaccae (SRL172) were used as stimulators of immune defense mechanisms and the results were compared with standard chemotherapy meglumine antimoniate.

Methods

Nineteen mongrel dogs aging 1-3 years old were used in this experiment. Infection was carried out in 15 out of 19 dogs using L. infantum, isolated from a naturally infected poly-symptomatic dog.

Results

All the cases showed positive serologic results by direct agglutination test during 30-60 days following inoculation. In the first group, which was under chemotherapy (Glucantime^R), one of the members showed recurrence of the disease despite rapid effect of the therapeutic protocol. Immunotherapy using SRL172 caused complete cleaning of the parasite in group 2, but the speed was less than Glucantime. Immunotherapy using L. major antigen combined with M. vaccae in group 3 and combine administration of immunotherapy and chemotherapy in group 4 both were with relapsing of one case in each group. Group 5 and 6 were consisted of positive and negative control dogs, respectively.

Conclusion

Immunotherapy seems to be an adjuvant in treatment of canine leishmaniasis but it needs more investigation for final confirmation.