New serological tools for improved diagnosis of human tegumentary leishmaniasis

Urine and serum-based ELISA using a recombinant protein and synthetic peptide for the diagnosis of tegumentary leishmaniasis

The diagnosis of tegumentary leishmaniasis (TL) presents problems by the variable sensitivity and specificity of the tests, and the biological samples used are also invasive. Here, ELISA experiments were performed using paired TL patient urine and serum samples in reaction against the recombinant LiHyS protein, a predicted B cell epitope and parasite antigenic extract (SLA). Two hundred and five paired samples were used, which were provided by TL patients, healthy controls and patients with Chagas disease, leprosy, malaria or HIV-infected. An urine-based ELISA showed sensitivity values of 100%, 92.1%, and 82.5%, when rLiHyS, peptide and SLA were used, respectively; and specificity of 100%, 87.6%, and 79.5%, respectively. A serum-based ELISA showed sensitivity values of 100%, 99.3%, and 81.5%, using rLiHyS, peptide and SLA, respectively, and sensitivity of 100%, 96.5%, and 72.2%, respectively. In both cases, rLiHyS presented the better performance to diagnose TL by using patient serum and urine.

A systematic review of peptide-based serological tests for the diagnosis of leishmaniasis

Serological methods should meet the needs of leishmaniasis diagnosis due to their high sensitivity and specificity, economical and adaptable rapid diagnostic test format, and ease of use. Currently, the performances of serological diagnostic tests, despite improvements with recombinant proteins, vary greatly depending on the clinical form of leishmaniasis and the endemic area. Peptide-based serological tests are promising as they could compensate for antigenic variability and improve performance, independently of Leishmania species and subspecies circulating in the endemic areas. The objective of this systematic review was to inventory all studies published from 2002 to 2022 that evaluate synthetic peptides for serological diagnosis of human leishmaniases and also to highlight the performance (e.g., sensitivity and specificity) of each peptide reported in these studies. All clinical forms of leishmaniasis, visceral and tegumentary, and all Leishmania species responsible for these diseases were considered. Following PRISMA statement recommendations, 1,405 studies were identified but only 22 articles met the selection criteria and were included in this systematic review. These original research articles described 77 different peptides, of which several have promising performance for visceral or tegumentary leishmaniasis diagnosis. This review highlights the importance of and growing interest in synthetic peptides used for serological diagnosis of leishmaniases, and their performances compared to some widely used tests with recombinant proteins.

New immunodiagnostic methods for human tegumentary leishmaniasis in the last 10 years: Technological Prospecting

Leishmaniasis is a neglected disease and more than 1 billion people live in endemic areas with the risk of infection worldwide. Although it is an important epidemiological issue, the gold standard method of diagnosis requires invasive sample collection and is accompanied by a high level of sensitivity variation in results. The present study aims to conduct a patent prospection of immunodiagnostic methods for human tegumentary leishmaniasis in the last 10 years, focused on those with high sensitivity and specificity, and simple usability. We searched seven patent databases: The LENS, WIPO, EPO, USPTO, Patent Inspiration, Google patents, and INPI. Eleven patents were found that satisfy our search criteria, with six of them being registered in 2017. Most patents were registered in Brazil. The information obtained here covers the main characteristics of the immunodiagnostic methods evaluated. Moreover, our prospective study reveals the latest biotechnological advancements achieved in the immunodiagnosis of tegumentary leishmaniasis, especially in Brazil, which holds the majority of patents in this subject. However, no patent for immunodiagnostic methods was found in the last three years, which raises concerns about the present and future trends of leishmaniasis diagnosis.

Potential antigenic targets used in immunological tests for diagnosis of tegumentary leishmaniasis: A systematic review

Immunological tests may represent valuable tools for the diagnosis of human tegumentary leishmaniasis (TL) due to their simple execution, less invasive nature and potential use as a point-of-care test. Indeed, several antigenic targets have been used with the aim of improving the restricted scenario for TL-diagnosis. We performed a worldwide systematic review to identify antigenic targets that have been evaluated for the main clinical forms of TL, such as cutaneous (CL) and mucosal (ML) leishmaniasis. Included were original studies evaluating the sensitivity and specificity of immunological tests for human-TL, CL and/or ML diagnosis using purified or recombinant proteins, synthetic peptides or polyclonal or monoclonal antibodies to detect Leishmania-specific antibodies or antigens. The review methodology followed PRISMA guidelines and all selected studies were evaluated in accordance with QUADAS-2. Thirty-eight original studies from four databases fulfilled the selection criteria. A total of 79 antigens were evaluated for the detection of antibodies as a diagnostic for TL, CL and/or ML by ELISA. Furthermore, three antibodies were evaluated for the detection of antigen by immunochromatographic test (ICT) and immunohistochemistry (IHC) for CL-diagnosis. Several antigenic targets showed 100% of sensitivity and specificity, suggesting potential use for TL-diagnosis in its different clinical manifestations. However, a high number of proof-of-concept studies reinforce the need for further analysis aimed at verifying true diagnostic accuracy in clinical practice.

Serological Approaches for Trypanosoma cruzi Strain Typing

Trypanosoma cruzi, the protozoan agent of Chagas' disease, displays a complex population structure made up of multiple strains showing a diverse ecoepidemiological distribution. Parasite genetic variability may be associated with disease outcome, hence stressing the need to develop methods for T. cruzi typing in vivo. Serological typing methods that exploit the presence of host antibodies raised against polymorphic parasite antigens emerge as an appealing approach to address this issue. These techniques are robust, simple, cost-effective, and are not curtailed by methodological/biological limitations intrinsic to available genotyping methods. Here, we critically assess the progress towards T. cruzi serotyping and discuss the opportunity provided by high-throughput immunomics to improve this field.

Recent advances and new strategies in Leishmaniasis diagnosis

Leishmaniasis is a set of complex and multifaceted syndromes, with different clinical manifestations, caused by different species of the genus Leishmania spp. that can be characterized by at least four syndromes: visceral leishmaniasis (VL, also known as kala-azar), post-kala-azar dermal leishmaniasis (PKDL), cutaneous leishmaniasis (CL), and mucocutaneous leishmaniasis (MCL). Among the most serious clinical forms, VL stands out, which causes the death of around 59,000 people annually. Fast and accurate diagnosis in VL is essential to reduce the disease's morbidity and mortality. There are a large number of diagnostic tests for leishmaniasis, however they do cross-react with other protozoa and their sensitivity changes according to the clinical form of the disease. Thus, it is essential and necessary to provide a diagnosis that is sufficiently sensitive to detect asymptomatic infected individuals and specific to discriminate individuals with other infectious and parasitic diseases, thus enabling more accurate diagnostic tools than those currently used. In this context, the aim of this review is to summarize the conventional diagnostic tools and point out the new advances and strategies on visceral and cutaneous leishmaniasis diagnosis.

Accuracy of diagnostic tests for American tegumentary leishmaniasis: a systematic literature review with meta-analyses

OBJECTIVES

To analyse the accuracy of American tegumentary leishmaniasis (ATL) diagnostic methods and evaluate the quality of the existing publications by means of a systematic review.

METHODS

Diagnostic tests evaluated in at least two studies with common reference standards were included in the sensitivity and/or specificity meta-analyses. Quality and susceptibility to bias were analysed using the QUADAS-2 and STARD tools.

RESULTS

The title and abstract of 3387 publications were evaluated after deduplication resulting from database searches. Thirty-eight studies were included in the review, and 26 of them had results inserted in meta-analyses. The diagnostic methods with the highest pooled sensitivity values were ELISA, polymerase chain reaction (PCR), indirect immunofluorescence reaction and Montenegro's intradermal reaction. Cytometry was assessed in only two studies and presented 100% sensitivity in both. Smear slide microscopy and histopathology showed low pooled values of sensitivity. For specificity, the highest pooled values were identified for PCR. High values were also identified for ELISA, except for studies in which the reference standard for defining negative participants included individuals with Chagas' disease or paracoccidioidomycosis, which also occurred for cytometry. IFR had lower specificities than ELISA. There was a predominance of case-control designs of phase 1 or 2 and only four studies were strongly recommended as evidence generators. Several reference standards were adopted, and different methods were assessed in a small number of studies.

CONCLUSION

PCR showed the highest accuracy for the diagnosis of ATL, and its use should be encouraged in clinical practice. ELISA is recommended for the screening of suspected individuals, but the possibility of cross-reactions should be considered. New validation studies for the tests evaluated in few publications and studies of phase 3 with appropriate methods are needed.

ENT involvement in Leishmania infections

INTRODUCTION

Leishmaniasis comprises a group of diseases caused by protozoan parasites of the genus Leishmania that are transmitted by the bite of infected phlebotomine mosquitoes from animal reservoirs. Three different clinical forms are generated: cutaneous, mucocutaneous and visceral. We present the findings in the head and neck of this disease observed in our health area.

PATIENTS AND METHODS

A review of the last 26 years in our hospital, noting the clinical, diagnostic and therapeutic characteristics of the cases detected.

RESULTS

Thirteen cases were identified, 7 cutaneous, 4 mucocutaneous and 2 visceral or kala-azar. The mean age was 53.7±10.8 years. Immunodeficiency was identified in 61% of the cases. The incidence of the disease was 1.5:100,000 inhabitants/year, with a prevalence of 2%. Of those infected, 69% had involvement of the ear-nose-throat area. In 12 cases the diagnosis was established by biopsy of the lesions. The time from clinical debut to diagnosis ranged from 3 to 10 months. Antimony compounds were used as treatment in 11 patients and amphotericin B in 3, alone or combined with the former. One cutaneous form resolved with excision of the lesion. Ninety-two percent healed clinically and parasitologically.

CONCLUSIONS

Leishmaniasis in Spain frequently entails cutaneous and mucocutaneous involvement, often of the skin of the head, face and neck or upper-airway mucosa. Its clinical presentation varies greatly, and it should be suspected if there is no response to conventional therapies and in conditions of immunodeficiency.

Serological Evaluation of Cutaneous Leishmania tropica Infection in Northern Israel

Leishmania spp. are medically important unicellular parasites transmitted by phlebotomine sand flies. The World Health Organization recently highlighted the importance of reliable diagnostic tools for leishmaniasis. Our study of human infection was conducted in two endemic foci of Leishmania tropica in the Galilee region, northern Israel. Elevated anti-Leishmania antibodies were present in the majority (78.6%) of L. tropica-PCR positive individuals. Moreover, the enzyme-linked immunosorbent assay showed high sensitivity, specificity, and negative and positive predictive values (ranging between 73% and 79%), thus fulfilling the basic requirement for future development of a serodiagnostic and screening tool. The anti-sand fly saliva antibodies used as biomarkers of exposure reflected the composition of the local sand fly fauna as well as the abundance of individual species. High levels of antibodies against vector salivary proteins may further indicate frequent exposure to sand flies and consequently a higher probability of Leishmania transmission.

Diagnostic application of recombinant Leishmania proteins and evaluation of their in vitro immunogenicity after stimulation of immune cells collected from tegumentary leishmaniasis patients and healthy individuals

The present study evaluated the cytokine profile in PBMC supernatants and the humoral response in mucosal leishmaniasis (ML) patients and in healthy subjects living in an endemic area. Four proteins, which had previously proven to be antigenic in the human disease, were tested: LiHyM, enolase, eukaryotic initiation factor 5a, and Beta-tubulin. Results showed that all of the proteins stimulated human cells with higher IFN-γ and lower IL-4 and IL-10 levels. The analysis of antibody isotypes correlated with cell response, since the IgG2 production was higher than IgG1 in both groups. By contrast, a Th2 response was found when an antigenic Leishmania extract was used. Serological analyses revealed high sensitivity and specificity values for the serodiagnosis of the disease, when compared to the data obtained using the antigenic preparation. In conclusion, this study presents new candidates to be evaluated as biomarkers in tegumentary leishmaniasis.

A conserved Leishmania hypothetical protein evaluated for the serodiagnosis of canine and human visceral and tegumentary leishmaniasis, as well as a serological marker for the posttreatment patient follow-up

In the present study, a conserved Leishmania hypothetical protein, LiHyE, was evaluated for the serodiagnosis of leishmaniasis. Results showed that it presented high sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) to serologically identify visceral leishmaniasis (VL) dogs when 40 positive sera and 95 cross-reactive samples were used. rLiHyE also showed the best results of sensitivity, specificity, PPV, and NPV to identify tegumentary leishmaniasis (TL) and VL patients when 45 leishmaniasis patients' sera and 90 cross-reactive samples were used. Results were better in comparison to those obtained when rA2 or Leishmania antigenic extract was employed as controls. The posttreatment follow-up showed that rLiHyE-specific antibodies declined significantly after the end of treatments, and a predominance of the IgG2 subclass was found in comparison to IgG1 levels in both TL and VL patients. In conclusion, rLiHyE can be considered a candidate for the serodiagnosis of canine and human leishmaniasis.

Selection strategy of phage-displayed immunogens based on an in vitro evaluation of the Th1 response of PBMCs and their potential use as a vaccine against Leishmania infantum infection

Background

The development of a vaccine for the prevention of visceral leishmaniasis (VL) still represents a significant unmet medical need. A human vaccine can be found if one takes into consideration that many people living in endemic areas of disease are infected but do not develop active VL, including those subjects with subclinical or asymptomatic infection.

Methods

In this study, a phage display was used to select phage-exposed peptides that were specific to immunoglobulin G (IgG) antibodies from asymptomatic and symptomatic VL patients, separating them from non-infected subjects. Phage clones presenting valid peptide sequences were selected and used as stimuli of peripheral blood mononuclear cells (PBMCs) obtained from both patients’ groups and controls. Those with higher interferon-gamma (IFN-γ)/interleukin (IL)-10 ratios were further selected for vaccination tests.

Results

Among 17 evaluated clones, two were selected, B1 and D11, and used to immunize BALB/c mice in an attempt to further validate their in vivo protective efficacy against Leishmania infantum infection. Both clones induced partial protection against the parasite challenge, which was evidenced by the reduction of parasitism in the evaluated organs, a process mediated by a specific T helper (Th)1 immune response.

Conclusions

To the best of our knowledge, this study is the first to use a rational strategy based on in vitro stimulation of human PBMCs with selected phage-displayed clones to obtain new immunogens against VL.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2576-8) contains supplementary material, which is available to authorized users.

An ELISA immunoassay employing a conserved Leishmania hypothetical protein for the serodiagnosis of visceral and tegumentary leishmaniasis in dogs and humans

In the present study, a conserved Leishmania hypothetical protein, namely LiHypA, was evaluated for the serodiagnosis of visceral and tegumentary leishmaniasis in dogs and humans. This protein showed a high amino acid sequence homology between viscerotropic and cutaneotropic Leishmania species. An enzyme-linked immunosorbent assay (ELISA) was developed using the recombinant antigen (rLiHypA), in addition to the A2 protein and two parasite antigenic preparations, which were used as controls. Regarding human diagnosis, results showed that rLiHypA was more sensitive and specific than ELISA-L. braziliensis SLA in detecting both cutaneous or mucosal leishmaniasis patients, but not those from Chagas disease patients or healthy subjects. Regarding canine diagnosis, this recombinant antigen showed higher sensitivity and specificity values, as well as a perfect accuracy to identify asymptomatic and symptomatic visceral leishmaniasis (VL) in dogs, but not those from vaccinated animals or those developing babesiosis, ehrlichiosis, or Chagas disease. However, using the rA2 protein or L. braziliensis SLA as controls, significant cross-reactivity was found when these samples were used, hampering their sensitivity and specificity values for the diagnosis. In this context, LiHypA could be considered a candidate to be evaluated for the serodiagnosis of visceral and tegumentary leishmaniasis in dogs and humans.

Evaluation of a hypothetical protein for serodiagnosis and as a potential marker for post-treatment serological evaluation of tegumentary leishmaniasis patients

The serodiagnosis for tegumentary leishmaniasis (TL) presents problems related to the sensitivity and/or specificity of the tests. In the present study, an enzyme-linked immunosorbent assay (ELISA) technique was used to evaluate the performance from a Leishmania braziliensis hypothetical protein, LbHyM, in an attempt to compare its serological reactivity with a soluble Leishmania antigenic preparation (SLA) for the serodiagnosis of cutaneous (CL) and mucosal (ML) leishmaniasis. LbHyM was predicted to be a kinesin-like protein by bioinformatics tools. Serum samples were collected from both CL and ML patients, as well as from those with Chagas disease and from healthy subjects living in endemic or non-endemic areas of TL. Also, sera were collected from patients before and after the treatments, seeking to evaluate their serological follow-up in relation to the anti-protein and anti-parasite antibody levels. When an ELISA-rLbHyM assay was performed, it proved to be significantly more sensitive than ELISA-L. braziliensis SLA in detecting both CL and ML patients. Also, when using sera from Chagas disease patients, the ELISA-rLbHyM proved to be more specific than ELISA-SLA. The anti-protein and anti-parasite antibody levels were also evaluated 6 months after the treatments, and treated patients showed significantly lower levels of specific-rLbHyM antibodies, when compared to the anti-parasite antibody levels. In conclusion, the ELISA-rLbHyM assay can be considered a confirmatory serological technique for the serodiagnosis of L. braziliensis infection and can also be used in the serological follow-up of treated patients, aiming to correlate the low anti-protein antibody levels with the improvement of the healthy state of the patients.