Despite advances, identification and formulation of safe and effective vaccine for long-lasting protection against leishmaniasis is still inadequate. In this study, we have identified a novel antigen, leishmanial elongation factor-1α (EF1-α), as an immunodominant component of solubilized leishmanial membrane antigens that reacts with visceral leishmaniasis (VL) sera and induces cellular proliferative and cytokine response in PBMCs of cured VL subjects. Leishmanial EF1-α is a 50 kDa antigen that plays a crucial role in pathogen survival by regulating oxidative burst in the host phagocytes. Previously, immunodominant truncated forms of EF1-α from different species of Leishmania have been reported. Formulation of the L. donovani 36 kDa truncated as well as the cloned recombinant EF1-α in cationic liposomes induce strong resistance to parasitic burden in liver and spleen of BALB/c mice through induction of DTH and a IL-10 and TGF-β suppressed mixed Th1/Th2 cytokine responses. Multiparametric analysis of splenocytes for generation of antigen-specific IFN-γ, IL2, and TNF-α producing lymphocytes indicate that cationic liposome facilitates expansion of both CD4+ as well as CD8+ memory and effector T cells. Liposomal EF1-α is a novel and potent vaccine formulation against VL that imparts long-term protective responses. Moreover, the flexibility of this formulation opens up the scope to combine additional adjuvants and epitope selected antigens for use in other disease forms also.
Immunosuppression is a characteristic feature of chronic leishmaniasis. The dynamicity and the functional cross talks of host immune responses during Leishmania infection are still not clearly understood. Here we explored the functional aspects of accumulation of immune suppressive cellular and cytokine milieu during the progression of murine visceral leishmaniasis. In addition to IL-10 and TGF-β, investigation on the responses of different subunit chains of IL-12 family revealed a progressive elevation of EBI-3 and p35 chains of IL-35 with Leishmania donovani infection in BALB/c mice. The expansion of CD25 and FoxP3 positive T cells is associated with loss of IFN-γ and TNF-α response in advanced disease. Ex-vivo and in vivo neutralization of TGF-β and EBI-3 suggests a synergism in suppression of host anti-leishmanial immunity. The down-regulation of EBI-3 and TGF-β is crucial for re-activation of JAK-STAT pathway for induction as well as restoration of protective immunity against L. donovani infection.
Leishmaniasis is a neglected protozoan disease that mainly affects the tropical as well as subtropical countries of the world. The primary option to control the disease still relies on chemotherapy. However, a hindrance to treatments owing to the emergence of drug-resistant parasites, enormous side effects of the drugs, their high cost, and requirement of long course hospitalization has added to the existing problems of leishmaniasis containment program. This review highlights the prospects of immunotherapy and/or immunochemotherapy to address the limitations for current treatment measures for leishmaniasis. In addition to the progress in alternate therapeutic strategies, the possibility and advances in developing preventive measures against the disease have been pointed. The review highlights our recent understandings of the protective immunology that can be exploited to develop an effective vaccine against leishmaniasis. Moreover, an update on the approaches that have evolved over the recent years are predominantly focused to overcome the current challenges in developing immunotherapeutic as well as prophylactic antileishmanial vaccines is discussed.
Numerous experimental DNA vaccines have been tested against Leishmania, whose clinical use is mostly limited due to insufficient CD8 + T cell-mediated immunity arising from poor gene delivery or presentation. Hence, there remains an important public health demand for a better vaccine adjuvant to combat leishmaniasis: ensuring proper antigen delivery coupled with strong cell mediated immune (CMI) response. To this end, we herein report, for the first time, novel cationic liposomes containing monophosphoryl lipid A (MPLA) intercalated into the 1,2-distearoyl-snglycero-3-phosphocholine (DSPC) lipid bilayer as an adjuvant for a DNA vaccine to enhance antileishmanial immunity. Interestingly, this MPLA-liposomal formulation strongly amplified the Leishmania donovani cysteine protease C (Ldcpc) DNA vaccine (i.e., pVAX1-cpc)-induced endogenous T cell and antibody responses with a Th1 biased profile. MPLA-liposomes could activate the splenic DCs in vivo and increased magnitude of antigen-specific polyfunctional CD4 + and CD8 + T cells together with CD8 + IFN-γ + memory generation in BALB/ c mice. Most importantly, in comparison to the mice receiving 'naked' pVAX1-cpc, immunization with MPLA-liposomal pVAX1-cpc DNA resulted in substantial reduction in parasite load, in association with reduced IL-10, IL-4 and TGF-β along with enhanced IFN-γ/IL-4 and IFN-γ/IL-10 cytokine ratios. Parasite burden inversely correlated with frequency of CD4 + and CD8 + T cells producing postinfection IFN-γ, IL-2, and TNF-α simultaneously, resulting in almost sterile protection (>98%) conferred by the DNA vaccine entrapped in MPLA-liposomes. This DNA vaccine afforded potent central and effector memory cell formation required for long-lasting immunity. Hence, this novel MPLA-DSPC adjuvant formulation approach could be a safe, biocompatible, and amenable choice as a strong immunostimulating agent delivery system holding promise against leishmaniasis and several other infectious diseases in the near future.
Visceral leishmaniasis (VL) is a threat in many developing countries. Plenty of efforts have been put to eliminate this disease, for which serodiagnosis remains the mainstay for VL control programs. New and improved antigens as diagnostic candidates are required since available antigens fail to demonstrate optimum performance in endemic areas equally. Moreover, the diagnosis is dependent on invasive serum sampling. In the current study, we cloned and expressed Leishmania donovani cysteine protease C (CPC) and evaluated its diagnostic and test of cure possibilities by detecting the antibody levels in human serum and urine through ELISA and immunoblot assays. Two immunodominant antigens, recombinant glycoprotein 63 (GP63) and elongation factor 1α (EF1α), identified earlier by our group were also assessed employing human serum and urine samples. Out of these three antigens in ELISA, CPC demonstrated the highest sensitivities being 98.15% and 96% positive in serum and urine of VL patients, respectively. Moreover, CPC depicted 100% specificity with serum and urine of nonendemic healthy controls as compared to GP63 and EF1α. Urine samples were found to be more specific than serum for distinguishing endemic healthy controls and other diseases for all the three antigens. In all cases CPC gave the most promising results. Unlike serum, urine tests demonstrated a significant decrease in antibody levels for CPC, GP63 and EF1α after six months of treatment. The diagnostic and test of cure performances of CPC in the immunoblot assay was found to be better than GP63 and EF1α. In conclusion, CPC, followed by GP63 and EF1α, may be utilized as candidates for diagnosis of VL and to assess treatment response.
Visceral leishmaniasis (VL) is one of the major global health concerns due to its association with morbidity and mortality. All available diagnostic tools have been, until now, unable to provide a very specific and cost-effective mode of detection for VL globally. Therefore, the design of robust, specific, and commercially translatable diagnostic tests is urgently required. Currently, we are attempting to identify and explore the diagnostic potential of a novel parasite antigen. Repressor of differentiation kinase 2 (RDK2), a serine/threonine kinase, has a versatile role in parasite life cycle progression. However, its role as a diagnostic candidate for VL has not been investigated. Herein, we cloned and over-expressed LdRDK2 and studied the recombinant RDK2 for the diagnosis of human VL using serum and urine samples. In silico analysis predicted that RDK2 is conserved among Leishmania species with the least conservation in humans. RDK2 developed immune-reactive bands with antibodies present in VL patients’ sera, and it demonstrated no cross-reactivity with sera from healthy controls and other diseases. Additionally, RDK2 antigen demonstrated a significant reactivity with IgG antibodies of VL patients’ sera, with 78% sensitivity and 86.67% specificity as compared to healthy controls and other diseases. Furthermore, we evaluated its utility for non-invasive diagnosis of VL using patients’ urine samples and found 93.8% sensitivity and 85.7% specificity. RDK2 was found to have better sensitivity and treatment response in patients’ urine compared to serum samples, indicating its role as a promising point of care (POC) antigen. In a nutshell, we explored the role of RDK2 as a potential diagnostic marker for VL in both invasive and non-invasive modes as well as its utility as a promising POC antigen for treatment response cases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.