Field validation of a Leishmania (Leishmania) mexicana exo-antigens ELISA for diagnosing tegumentary leishmaniasis in regions of Leishmania (Viannia) predominance

Advancement in leishmaniasis diagnosis and therapeutics: An update

Leishmaniasis is regarded as a neglected tropical disease by World Health Organization (WHO) and is ranked next to malaria as the deadliest protozoan disease. The primary causative agents of the disease comprise of diverse leishmanial species sharing clinical features ranging from skin abrasions to lethal infection in the visceral organs. As several Leishmania species are involved in infection, the role of accurate diagnosis becomes pivotal in adding new dimensions to anti-leishmanial therapy. Diagnostic methods must be fast, reliable, easy to perform, highly sensitive, and specific to differentiate among similar parasitic diseases. Herein, we present the conventional and recent approaches impended for the disease diagnosis and their sensitivity, specificity, and clinical application in parasite detection. Furthermore, we have also elaborated various new methods to cure leishmaniasis, which include host-directed therapies, drug repurposing, nanotechnology, and combinational therapy. This review addresses novel techniques and innovations in leishmaniasis, which can aid in unraveling new strategies to fight against the deadly infection.

Diagnostic accuracy of Enzyme-Linked Immunosorbent Assays to detect anti-Leishmania antibodies in patients with American Tegumentary Leishmaniasis: a systematic review

American Tegumentary leishmaniasis (ATL) is an infectious disease caused by several species of Leishmania . Even though the direct detection of parasites has low sensitivity, it is still the gold standard for the laboratory diagnosis of ATL. Recent studies have shown promising results of Enzyme-Linked Immunosorbent Assays ( ELISAs) using recombinant antigens. The aim of this study is to compare the accuracy of ELISAs using novel antigens with the standard ELISA based on soluble antigens of Leishmania (SLA) to diagnose ATL. Studies that analyzed patients with ATL and studies that evaluated the diagnostic accuracy of ELISAs using novel antigens and SLA were included. The Fourteen studies from PubMed, Regional Portal of the Virtual Health Library (BVS), Brazilian Society of Dermatology, Virtual Health Library (IBECS), Literature in the Health Sciences in Latin America and the Caribbean (LILACS), Medical Literature Analysis and Retrieval System Online (Medline), Elsevier Embase, Cochrane Library, The National Institute for Health and Care Excellence (NICE), and Cumulative Index to Nursing and Allied Health Literature (CINAHL) were included. The novel ELISA antigens showed a high sensitivity (93.8%-100%) and specificity (82.5-100%), a better diagnostic performance than SLA-based ELISAs (1-97.4% and 57.5-100%, respectively). Only 10 studies analyzed cross-reactions in serum samples from patients with Chagas disease, and only two studies reported a percentage of cross-reactivity. In this systematic review, the novel ELISA antigens showed better sensitivity and specificity with respect to SLA-based ELISAs. However, a meta-analysis should be performed to confirm this finding.

Relationship between pemphigus and American tegumentary leishmaniasis: insights from serological and genetic profiles

Background

Antibodies against Leishmania peptides (Lbr-peps) and desmogleins (Dsgs) have been reported in pemphigus foliaceus (PF) and leishmaniasis patients, respectively. We aimed to compare serological and genetic features in a Brazilian region endemic for American tegumentary leishmaniasis (ATL) and pemphigus.

Methods

Commercial anti-Dsg ELISA and in-house ELISA with Lbr-peps were used to determine the serological profile, in addition to immunoblotting (IB) and indirect immunofluorescence (IIF) assays. HLA-DRB1 and -DQA1/DQB1 alleles were characterized by PCR combined with sequence-specific oligonucleotide probes (PCR-SSOP). The serological and genetic profiles were compared using 78 PF, 62 pemphigus vulgaris (PV) and 58 ATL patients against 163 and 1592 healthy controls, respectively.

Results

Some ATL patients showed positive results for anti-Dsg1 and/or anti-Dsg3 antibodies. They also revealed 130, 160 and/or 230 kDa epidermal peptides in IB. Moreover, some ATL samples exhibited pemphigus or a bullous pemphigoid pattern in IIF. ELISA and IB assays showed Lbr-peps in pemphigus patients. HLA-DQA1*01 and -DQA1*01:02 were protective and susceptibility alleles for ATL, respectively, but the opposite for pemphigus.

Conclusions

Anti-Dsgs in ATL may represent epiphenomena. Anti-Lbr-pep antibodies in pemphigus suggest a previous infection. A differential association of the HLA profile may contribute to the lack of co-association between pemphigus and ATL.

Analysis of the Antigenic and Prophylactic Properties of the Leishmania Translation Initiation Factors eIF2 and eIF2B in Natural and Experimental Leishmaniasis

Different members of intracellular protein families are recognized by the immune system of the vertebrate host infected by parasites of the genus Leishmania. Here, we have analyzed the antigenic and immunogenic properties of the Leishmania eIF2 and eIF2B translation initiation factors. An in silico search in Leishmania infantum sequence databases allowed the identification of the genes encoding the α, β, and γ subunits and the α, β, and δ subunits of the putative Leishmania orthologs of the eukaryotic initiation factors F2 (LieIF2) or F2B (LieIF2B), respectively. The antigenicity of these factors was analyzed by ELISA using recombinant versions of the different subunits. Antibodies against the different LieIF2 and LieIF2B subunits were found in the sera from human and canine visceral leishmaniasis patients, and also in the sera from hamsters experimentally infected with L. infantum. In L. infantum (BALB/c) and Leishmania major (BALB/c or C57BL/6) challenged mice, a moderate humoral response against these protein factors was detected. Remarkably, these proteins elicited an IL-10 production by splenocytes derived from infected mice independently of the Leishmania species employed for experimental challenge. When DNA vaccines based on the expression of the LieIF2 or LieIF2B subunit encoding genes were administered in mice, an antigen-specific secretion of IFN-γ and IL-10 cytokines was observed. Furthermore, a partial protection against murine CL development due to L. major infection was generated in the vaccinated mice. Also, in this work we show that the LieIF2α subunit and the LieIF2Bβ and δ subunits have the capacity to stimulate IL-10 secretion by spleen cells from naïve mice. B-lymphocytes were identified as the major producers of this anti-inflammatory cytokine. Taking into account the data found in this study, it may be hypothesized that these proteins act as virulence factors implicated in the induction of humoral responses as well as in the production of the down-regulatory IL-10 cytokine, favoring a pathological outcome. Therefore, these proteins might be considered markers of disease.

Leptomonas seymouri and Crithidia fasciculata exoantigens can discriminate human cases of visceral leishmaniasis from American tegumentary leishmaniasis ones

Exoantigens (exo) from Leptomonas seymouri and Crithidia fasciculata were used in an enzyme linked immunosorbent assay (ELISA), showing 100% reactivity with sera from visceral leishmaniasis (VL) cases, and no reactivity with American tegumentary leishmaniasis (ATL) ones. Our results have indicated that these exoantigens can be applied in the discrimination of VL and ATL cases.

Field Validation of SYBR Green- and TaqMan-Based Real-Time PCR Using Biopsy and Swab Samples To Diagnose American Tegumentary Leishmaniasis in an Area Where Leishmania (Viannia) braziliensis Is Endemic

The precise diagnosis of American tegumentary leishmaniasis (ATL) is an essential task due to the disease's associated morbidity. A noninvasive, extremely sensitive, and highly specific exam is critical, particularly for mucosal leishmaniasis (ML), in which a low parasite quantity is expected. We aimed to compare the diagnostic accuracy of swab and biopsy sample analysis using SYBR Green- and TaqMan-based real-time PCR (qPCR) assays with that of a composite reference standard consisting of the Montenegro skin test, serology, histopathology, smears, culture, and conventional PCR. In total, 55 patients with ATL (ML, 18 patients; cutaneous leishmaniasis [CL], 37 patients) and 36 patients without ATL were studied. qPCR analysis of swabs was more accurate when using SYBR Green (87.88%; 95% confidence interval [CI], 77.86 to 93.73 patients) than when using TaqMan (78.79%; 95% CI, 67.49 to 86.92%) (P = 0.031). SYBR Green (84.72%; 95% CI, 74.68 to 91.25%) was also more accurate than TaqMan (73.61%; 95% CI, 62.42 to 82.41%) for biopsy samples (P = 0.008). All qPCR methods were 100% specific. Swabs and biopsy specimens had similar sensitivity when using the same chemistry (P = 0.125 for SYBR Green and P = 0.625 for TaqMan). Moreover, qPCR achieved better performance than most existing techniques used for the diagnosis of ATL and also detected the Leishmania parasite in a greater proportion of patients than the associated histopathology, smear, culture, and conventional PCR techniques did. Swabs therefore represent a useful diagnostic tool because they not only are noninvasive but also can achieve an accuracy similar to that of biopsy samples. The high accuracy of SYBR Green-based qPCR may also reduce the requirement for associated parasitological tests for ATL diagnosis.