Role of higher levels of post-challenge antibodies in protective vaccination against Leishmania tropica infection of BALB/c mice

Objective:To study the role of antibodies in protection against Leishmania tropica(L.tropica)infection in the experimental model of BALB/c mice.Methods:BALB/c mice were vaccinated against L.tropica by soluble Leishmania antigen or recombinant L.tropica stress-inducible protein-1(LtSTI1)of L.tropica,and against Leishmania major(L.major)by soluble Leishmania antigen.Monophosphoryl lipid A was used as an adjuvant.The L.tropica-or L.major-vaccinated mice were challenged by L.tropica or L.major,respectively.The levels of anti-Leishmania antibodies(IgG1 and IgG2 a)were determined after vaccination and after challenge.Results:All vaccinated groups caused a higher antibody response in comparison with the control group.The L.major-vaccinated group showed lower IgG1 response than the control group after the challenge.Conversely,in L.tropica-vaccinated mice,the levels of antibodies were higher than the control group.Moreover,the group receiving rLtSTI1 and monophosphoryl lipid A showed higher levels of antibodies than those of the rLtSTI1 group.In vaccinated mice,antibody responses against L.tropica remained high until 16 weeks after the challenge.Conclusions:The higher levels of post-challenge antibodies are associated with protective vaccination against L.tropica infection of BALB/c mice.Our findings provide new insight into the association of antibody with vaccine-induced protective immunity against L.tropica infection.More studies are needed to clarify the role of antibody in protection against L.tropica.

Tioxolone niosomes exert antileishmanial effects on Leishmania tropica by promoting promastigote apoptosis and immunomodulation

Objective: To explore the antileishmanial effect of tioxolone and its niosomal form against Leishmania tropica. Methods: Tioxolone niosomes were prepared by the hydration method and were evaluated for morphology, size, release study, and encapsulation efficiency. The cytotoxicity of tioxolone and its niosomal form was measured by MTT assay, leishmanicidal activity against promastigote and amastigote by MTT assay, apoptosis by flow cytometry, IL-12, IL-10 and metacaspase gene expression levels by q-PCR. Results: Span/Tween 40 and Span/Tween 60 niosomes had good physical stability as depicted in their size distribution curves and high encapsulation efficiency(>99%). The release profile of the entrapped compounds showed Fickian’s model of tioxolone delivery based on diffusion through lipid bilayers. With the IC50 value for amastigote as(24.5±2.1) μg/mL and selectivity index as 10.5, the Span/Tween 60 niosome(NT2) had a superior effect to other drugs. The CC50 value and IC50 of promastigote value for NT2 were(257.5±24.5) μg/mL and(164.8±20.6) μg/mL, respectively. The flow cytometric analysis showed that tioxolone and niosomal forms induced apoptosis of Leishmania tropica promastigotes in a dose-dependent manner. NT2 increased the expression level of IL-12 and metacaspase genes and decreased the expression level of the IL-10 gene.Conclusions: Niosomes of tioxolone play an immunomodulatory role in increasing Th1 cytokine profile and inhibiting the Th2 cytokine profile. It could be used for treatment of anthroponotic cutaneous leishmaniasis.

First report on natural Leishmania infection of Phlebotomus sergenti due Leishmania tropica by high resolution melting curve method in Southeastern Iran

Objective:To identify the Leishmania species in infected sand flies by Real-time PCR coupled with HRM analysis.Methods:Real-time PCR coupled with HRM analysis targeting the first internal transcribed spacer(ITS1)of nuclear ribosomal DNA as the genetic marker was used to identify and distinguish Lelthmania species in sand flies specimens.Results:Three out of 115females of Phlebotomus sergenti(P.sergenti)(2.6%)were positive to Leishmania tropica(L.tropica).Conclusions:This is the first report on P.sergenti as the main and proven vector of anthroponitic cutaneous leishmaniasis in Dehbakri County using Real-time PCR coupled with HUM analysis.This method is rapid,sensitive and specific for diagnosing of parasites in infected Sand flies and ideal for large scale genotyping projects.

Effects of different colours in the visible region on <i>Leishmania Tropica</i>

The aim of this study was to investigate the wavelength-dependency of chromotherapy effects on cutaneous Leishmaniasis parasite growth. Chromotherapy uses visible range radiations to improve healing;however, its effects on parasite are not well understood. Leishmania Tropica was irradiated using seven (7) different wavelengths of visible region. Optical density was observed, which showed that red colour (644 nm) wavelength inhibited the growth of parasite while other colour wavelengths also affected the growth of parasite. It is, therefore, suggested that as red colour inhibits the growth of parasite so patients suffering from l.tropica can be treated with the application of red colour.

Effect of Vigna radiata, Tamarix ramosissima and Carthamus lanatus extracts on Leishmania major and Leishmania tropica: An in vitro study

Objective:Current therapy strategies of leishmaniasis have some problems such as high cost,toxicity and side effects.Plant extracts can be a source of drugs to control leishmaniasis.In this study,the effect of hydroalcoholic and chloroformic extracts of Vigna radiata,Tamarix ramosissima,and Carthamus lanatus on Leishmania major and L.tropica was studied.Methods:The plant samples were collected from west of Iran and their extracts were prepared.Antipromastigote activity assay of all extracts was done using tetrazolium-dye assay.Results:Only high concentrations of V.radiata and C.lanatus were able to inhibit Leishmania,while both high and low concentrations of T.ramosissima had antileishmanial effect.No difference was observed between hydroalcoholic with chloroformic extract of each plant.Conclusion:Altogether,the results revealed the antileishmanial activity of T.ramosissima extracts against L.major and L.tropica,indicating its potential as an antileishmanial agent.

First report on molecular characterization of Leishmania species from cutaneous leishmaniasis patients in southern Khyber Pakhtunkhwa province of Pakistan

Objective: To report presence of Leishmania major in Khyber Pakhtunkhwa of Pakistan, where cutaneous leishmaniasis(CL) is endemic and was thought to be caused by Leishmania tropica only. Methods: Biopsy samples from 432 CL suspected patients were collected from 3 southern districts of Khyber Pakhtunkhwa during years 2011–2016. Microscopy on Giemsa stained slides were done followed by amplification of the ribosomal internal transcribed spacer 1 gene. Results: Leishmania amastigotes were detected by microscopy in 308 of 432 samples(71.3%) while 374 out of 432 samples(86.6%) were positive by ribosomal internal transcribed spacer 1 PCR. Subsequent restriction fragment length polymorphism confirmed Leishmania tropica in 351 and Leishmania major in 6 biopsy samples. Conclusions: This study is the first molecular characterization of Leishmania species in southern Khyber Pakhtunkhwa. It confirmed the previous assumptions that anthroponotic CL is the major CL form present in Khyber Pakhtunkhwa province. Furthermore, this is the first report of Leishmania major from a classical anthroponotic CL endemic focus identified in rural areas of Kohat district in southern Khyber Pakhtunkhwa.

First molecular identification of Leishmania species in a new endemic area of cutaneous leishmaniasis in Lorestan,Iran

Objective:To identify Leishman{u using PCR.Methods:This studs was conducted from April2009 to March 2011 in order to identify Leishmania species in a new endemic area of CL in Lorestan.Iran.Samples were taken from 62 patients that referred to the health centers in different cities of Lorestan province,the presence of Leishmcania was confirmed using direct smear and then grown in NNN media and mass cultured in RPM!1640 medium supplemented with 10%heat-inactivated fetal bovine serum.DNA was extracted from cultured promastigotes and used in P15-PCR.Results:45(72.6%)samples out of 62 showed a hand in the range of 485 hp and 17(27.4%)with a hand in the range of 626 hp which were similar to standard strains of Leichmania tropica(L.tropical and Leishnrania major(L.major),respectively.50(65.80%)of samples were collected from people with no history of travel in at least a year prior to the onset which shows that indigenous source of infection.Conclusions:Since the vector and reservoir of the two species are different.so precise and extensive control and prevention methods should be designed and earned out.

Concomitant visceral and localized cutaneous leishmaniasis in two Moroccan infants

Background:Leishmaniases are vector-borne diseases caused by the protozoa of the Leishmania genus.The clinical spectrum of these diseases extends from benign dermal lesions to visceral forms.In the Mediterranean region,zoonotic visceral leishmaniasis(ZVL)is caused by L.infantum.If untreated within two years,the disease usually leads to death.In Morocco,ZVL is endemic in the north,with a hundred cases notified each year,mostly in children aged below five years.Here,we report on two clinical observations in infants presenting unusual concomitant VL and cutaneous leishmaniasis(CL)in Morocco.Case presentation:In this case study,we report on two infants aged nine and 12 months old.They both have a history of febrile splenomegaly,anemia,and pallor of mucous membranes.Visceral leishmaniasis was confirmed by parasitological diagnosis(positive bone marrow smear and screening of anti-L.infantum antibodies).However,the clinical examination also showed cutaneous lesions that suggested the presence of CL.This was reinforced by the patients having a history of living or traveling to endemic foci.Thus,direct examination,culture,and PCR-RFLP(ITS1-Hae 3)were carried out on the patients’dermal exudates.In one of the infants,CL was associated with L.infantum,while in the other it was associated with L.tropica.The infants were treated as according to the recommendations of the Ministry of Health.Both patients were cured in two months;defervescence,reduction of splenomegaly,and healing of cutaneous lesions were all observed.Conclusions:These singular patients illustrate the clinical polymorphism of CL and the necessity of updating the differential diagnosis of leukemia-like syndromes,including VL,in children living in or travelling to known endemic areas.These observations suggest a change in the Mediterranean VL phenotype that may be associated with CL.