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Leishmaniasis is considered as one of the 20 neglected tropical diseases. Current methods of leishmanial diagnosis depend on conventional laboratory‐based techniques, which are time‐consuming, costly and require special equipment and trained personnel. In this context, we aimed to provide an immuno field effect transistors (ImmunoFET) biosensor that matches the conventional standards for point‐of‐care (POC) monitoring and detection of Leishmania (L.) donovani/Leishmania major. Crude antigens prepared by repeated freeze thawing of L. donovani/L. major stationary phase promastigotes were used for ELISA and ImmunoFETs. Lesishmania‐specific antigens were serially diluted in 1× PBS from a concentration of 106–102 parasites/mL. A specific polyclonal antibody‐based sandwich ELISA was established for the detection of Leishmania antigens. An immunoFET technology‐based POC novel assay was constructed for the detection of Leishmania antigens. Interactions between antigen–antibody at the gate surface generate an electrical signal that can be measured by semiconductor field‐effect principles. Sensitivity was considered and measured as the change in current divided by the initial current. The final L. donovani/L. major crude antigen protein concentrations were measured as 1.50 mg/mL. Sandwich ELISA against the Leishmania 40S ribosomal protein detected Leishmania antigens could detect as few as 100 L. donovani/L. major parasites. An immunoFET biosensor was constructed based on the optimization of aluminium gallium nitride/gallium nitride (AlGaN/GaN) surface oxidation methods. The device surface was composed by an AlGaN/GaN wafer with a 23 nm AlGaN barrier layer, a 2 μm GaN layer on the silicon carbide (SiC) substrate for Leishmania binding, and coated with a specific antibody against the Leishmania 40S ribosomal protein, which was successfully detected at concentrations from 106 to 102 parasites/mL in 1× PBS. At the concentration of 104 parasites, the immunoFETs device sensitivities were 13% and 0.052% in the sub‐threshold regime and the saturation regime, respectively. Leishmania parasites were successfully detected by the ImmunoFET biosensor at a diluted concentration as low as 150 ng/mL. In this study, the developed ImmunoFET biosensor performed well. ImmunoFET biosensors can be used as an alternative diagnostic method to ELISA. Increasing the sensitivity and optimization of immuno‐FET biosensors might allow earlier and faster detection of leishmaniasis. [ABSTRACT FROM AUTHOR]

Leishmaniasis is a neglected tropical disease caused by Leishmania protozoa transmitted by infected sand flies. Vaccination through leishmanization with live Leishmania major has been used successfully but is no longer practiced because it resulted in occasional skin lesions. A second generation leishmanization is described here using a CRISPR genome edited L. major strain (LmCen−/−). Notably, LmCen−/− is a genetically engineered centrin gene knock-out mutant strain that is antibiotic resistant marker free and does not have detectable off-target mutations. Mice immunized with LmCen−/− have no visible lesions following challenge with L. major-infected sand flies, while non-immunized animals develop large and progressive lesions with a 2-log fold higher parasite burden. LmCen−/− immunization results in protection and an immune response comparable to leishmanization. LmCen−/− is safe since it is unable to cause disease in immunocompromised mice, induces robust host protection against vector sand fly challenge and because it is marker free, can be advanced to human vaccine trials. Here, the authors engineer an attenuated knock-out Leishmania (LmCen−/−) vaccine that is safe in immunocompromised mice and induces an immune response and protection similar to leishmanization with wild-type Leishmania. Since LmCen−/− is antibiotic resistant marker free, it is a candidate for clinical development. [ABSTRACT FROM AUTHOR]

Vaccination with durable immunity is the main goal and fundamental to control leishmaniasis. To stimulate the immune response, small numbers of parasites are necessary to be presented in the mammalian host. Similar to natural course of infection, strategy using live vaccine is more attractive when compared to other approaches. Live vaccines present the whole spectrum of antigens to the host immune system in the absence of any adjuvant. Leishmanization was the first effort for live vaccination and currently used in a few countries against cutaneous leishmaniasis, in spite of their obstacle and safety. Then, live attenuated vaccines developed with similar promotion of creating long-term immunity in the host with lower side effect. Different examples of attenuated strains are generated through long-term in vitro culturing, culturing under drug pressure, temperature sensitivity, and chemical mutagenesis, but none is safe enough and their revision to virulent form is possible. Attenuation through genetic manipulation and disruption of virulence factors or essential enzymes for intracellular survival are among other approaches that are intensively under study. Other designs to develop live vaccines for visceral form of leishmaniasis are utilization of live avirulent microorganisms such as Lactococcus lactis, Salmonella enterica, and Leishmania tarentolae called as vectored vaccine. Apparently, these vaccines are intrinsically safer and can harbor the candidate antigens in their genome through different genetic manipulation and create more potential to control Leishmania parasite as an intracellular pathogen. [ABSTRACT FROM AUTHOR]

Background: New drugs are needed for leishmaniasis because current treatments such as pentavalent antimonials are toxic and require prolonged administration, leading to poor patient compliance. Ibrutinib is an anticancer drug known to modulate T-helper type 1 (Th1)/Th2 responses and has the potential to regulate immunity against infectious disease.Methods: In this study, we evaluated the efficacy of oral ibrutinib as a host-targeted treatment for visceral leishmaniasis (VL) caused by Leishmania donovani using an experimental mouse model.Results: We found that oral ibrutinib was significantly more effective than the pentavalent antimonial sodium stibogluconate (70 mg/kg) for the treatment of VL caused by L. donovani. Ibrutinib treatment increased the number of interleukin 4- and interferon γ-producing natural killer T cells in the liver and spleen and enhanced granuloma formation in the liver. Further, ibrutinib treatment reduced the influx of Ly6Chi inflammatory monocytes, which mediate susceptibility to L. donovani. Finally, ibrutinib treatment was associated with the increased production of the cytokines interferon γ, tumor necrosis factor α, interleukin 4, and interleukin 13 in the liver and spleen, which are associated with protection against L. donovani.Conclusions: Our findings show that oral ibrutinib is highly effective for the treatment of VL caused by L. donovani and mediates its antileishmanial activity by promoting host immunity. Therefore, ibrutinib could be a novel host-targeted drug for the treatment of VL. [ABSTRACT FROM AUTHOR]