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

Big is not better: Comparing two alpha-Gal-bearing glycotopes in neoglycoproteins as biomarkers for Leishmania (Viannia) braziliensis infection

The protozoan parasite Leishmania (Viannia) braziliensis is among Latin America's most widespread Leishmania species and is responsible for tegumentary leishmaniasis (TL). This disease has multiple clinical presentations, with cutaneous leishmaniasis (CL) being the most frequent. It manifests as one or a few localized skin ulcers, which can spread to other body areas. Hence, early diagnosis and treatment, typically with pentavalent antimonials, is critical. Traditional diagnostic methods, like parasite culture, microscopy, or the polymerase chain reaction (PCR) for detection of the parasite DNA, have limitations due to the uneven distribution of parasites in biopsy samples. Nonetheless, studies have revealed high levels of parasite-specific anti-α-Gal antibodies in L. (V.) braziliensis-infected patients. Previously, we demonstrated that the neoglycoprotein NGP28b, consisting of the L. (Leishmania) major type-2 glycoinositolphospholipid (GIPL)-3-derived trisaccharide Galpα1,6Galpα1,3Galfβ conjugated to bovine serum albumin (BSA) via a linker, acts as a reliable serological biomarker (BMK) for L. (V.) braziliensis infection in Brazil. This indicates the presence of GIPL-3 or a similar structure in this parasite, and its terminal trisaccharide either functions as or is part of an immunodominant glycotope. Here, we explored whether extending the trisaccharide with a mannose unit would enhance its efficacy as a biomarker for the serological detection of L. (V.) braziliensis. We synthesized the tetrasaccharide Galpα1,6Galpα1,3Galfβ1,3Manpα(CH2)3SH (G31SH) and conjugated it to maleimide-functionalized BSA to afford NGP31b. When we assessed the efficacy of NGP28b and NGP31b by chemiluminescent enzyme-linked immunosorbent assay on a cohort of CL patients with L. (V.) braziliensis infection from Bolivia and Argentina against a healthy control group, both NGPs exhibited similar or identical sensitivity, specificity, and accuracy. This finding implies that the mannose moiety at the reducing end is not part of the glycotope recognized by the parasite-specific anti-α-Gal antibodies in patients' sera, nor does it exert a relevant influence on the terminal trisaccharide's conformation. Moreover, the mannose does not seem to inhibit glycan-antibody interactions. Therefore, NGP31b is a viable and dependable BMK for the serodiagnosis of CL caused by L. (V.) braziliensis.

A Review on the use of Synthetic and Recombinant Antigens for the Immunodiagnosis of Tegumentary Leishmaniasis

Improving the diagnostic technology used to detect tegumentary leishmaniasis (TL) is essential in view of it being a widespread, often neglected tropical disease, with cases reported from the Southern United States to Northern Argentina. Recombinant proteins, recombinant multiepitope proteins, and synthetic peptides have been extensively researched and used in disease diagnosis. One of the benefits of applying these antigens is a measurable increase in sensitivity and specificity, which improves test accuracy. The present review aims to describe the use of these antigens and their diagnostic effectiveness. With that in mind, a bibliographic survey was conducted on the PudMed platform using the search terms "tegumentary leishmaniasis" AND "diagno", revealing that recombinant proteins have been described and evaluated for their value in TL diagnosis since the 1990s. However, there was a spike in the number of publications using all of the antigens between 2013 and 2022, confirming an expansion in research efforts to improve diagnosis. Moreover, all of the studies involving different antigens had promising results, including improved sensitivity and specificity. These data recognize the importance of doing research with new technologies focused on developing quick, more effective diagnostic kits as early diagnosis facilitates treatment.

Serodiagnosis and therapeutic monitoring of New-World tegumentary leishmaniasis using synthetic type-2 glycoinositolphospholipid-based neoglycoproteins

American tegumentary leishmaniasis (TL) caused by Leishmania braziliensis is characterized by a spectrum of clinical presentations, ranging from localized cutaneous ulcers (CL), mucosal (ML), or disseminated (DL) disease, to a subclinical (SC) asymptomatic form. Current diagnosis based on parasite culture and/or microscopy lacks sensitivity and specificity. Previous studies showed that patients with CL and ML have very high levels of Leishmania-specific anti-α-Gal antibodies. However, the native parasite α-Gal glycotope(s) is(are) still elusive, thus they have not yet been explored for a more accurate TL diagnosis. Using a chemiluminescent immunoassay, we evaluated the seroreactivity of TL patients across its clinical spectrum, and of endemic (EC) and nonendemic healthy controls (NEC) against three synthetic neoglycoproteins (NGP29b, NGP30b, and NGP28b), respectively comprising the L. major-derived type-2 glycoinositolphospholipid (GIPL)-1 (Galfβ1,3Manα), GIPL-2 (Galα1,3Galfβ1,3Manα), and GIPL-3 (Galα1,6Galα1,3Galfβ) glycotopes. Contrary to NGP29b and NGP30b, NGP28b exhibited high sensitivity and specificity to a CL serum pool. More importantly, NGP28b reacted strongly and specifically with individual sera from distinct clinical forms of TL, especially with SC sera, with 94% sensitivity and 97% specificity, by post-two-graph receiver-operating characteristic curve analysis. Contrary to NGP29b, NGP28b showed low cross-reactivity with Chagas disease and control (NEC/EC) sera. Additionally, seroreactivity of CL patients against NGP28b was significantly decreased after successful chemotherapy, indicating that L. braziliensis-specific anti-α-Gal antibodies may serve as an early biomarker of cure in CL. Our data also points towards the applicability of L. major type-2 GIPL-3-derived Galα1,6Galα1,3Galfβ glycotope for the serological diagnosis of American TL, particularly of the subclinical form.

Non-Endemic Leishmaniases Reported Globally in Humans between 2000 and 2021—A Comprehensive Review

Leishmaniases are human and animal parasitic diseases transmitted by phlebotomine sand flies. Globalization is an important driver of the burden and in the current dynamics of these diseases. A systematic review of articles published between 2000 and 2021 was conducted using the PubMed search engine to identify the epidemiology and clinical management of imported human leishmaniases as a fundamental step to better manage individual cases and traveler and migrant health from a global perspective. A total of 275 articles were selected, representing 10,341 human imported cases. Identified drivers of changing patterns in epidemiology include conflict and war, as well as host factors, such as immunosuppression, natural and iatrogenic. Leishmania species diversity associated with different clinical presentations implies diagnostic and treatment strategies often complex to select and apply, especially in non-endemic settings. Thus, diagnostic and management algorithms for medical clinical decision support are proposed. Increased surveillance of non-endemic cases, whether in vulnerable populations such as refugees/migrants and immunocompromised individuals or travelers, could improve individual health and mitigate the public health risk of introducing Leishmania species into new areas.

A comprehensive and comparative proteomic analysis of horse serum proteins in colitis

BACKGROUND

Equine colitis is a diarrhoeal disease caused by inflammation of the large bowel and can potentially be life-threatening due to its rapid progression. Pathogenesis is multifactorial and pathophysiology is highly complicated, therefore, reliable diagnostic biomarkers are needed in the veterinary field.

OBJECTIVE

Serum is one of the most commonly used diagnostic tools in equine clinical investigation. To discover diagnostic or prognostic protein markers for colitis in horse serum, comprehensive and comparative proteomic analysis was conducted using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

STUDY DESIGN

Case-control study.

METHODS

Serum samples were collected from 36 healthy Thoroughbreds and 12 Thoroughbreds with colitis. Serum from each horse suffering from colitis was collected daily until death or recovery. Collected sera were digested with trypsin. Peptides obtained from serum proteins were measured by Q-Exactive HF Orbitrap mass spectrometer. The identification and quantification of peptides were performed using Proteome Discoverer version 2.2.

RESULTS

On day 1 of treatment, eight proteins in the colitis group were upregulated (P < .05, more than a twofold change) compared with the healthy group. Among the eight proteins, biliverdin reductase B was significantly upregulated (P < .05) in the non-survivor group (n = 5) compared with the survivor group (n = 7). On the last day of the treatment, haemoglobin subunit alpha, clusterin, glyceraldehyde-3-phosphate dehydrogenase, lipopolysaccharide-binding protein, and biliverdin reductase B showed significant increases (P < .05) in the non-survivor group.

MAIN LIMITATIONS

The number of the identified proteins is limited due to the existence of abundant proteins.

CONCLUSIONS

Measuring the changes of these proteins together may enable a potential prognosis or early diagnosis of horses suffering from colitis.

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.

Immunoblot for the Diagnosis of Cutaneous Leishmaniasis in French Guiana

Cutaneous leishmaniasis (CL) is firmly established in South America. We aimed to assess the detection of IgG antibodies against 14 and/or 16 kDa antigens by immunoblot (IB) for CL serological diagnosis in French Guiana, an area where many endemic pathogens could interfere with it. This study was performed retrospectively on sera from 141 patients at the Cayenne tertiary hospital: 30 were patients with confirmed CL, 71 were diagnosed with various other endemic pathogens, 11 were diagnosed with an autoimmune disease, and 29 controls had no history of CL. Antibodies bound to the 14 and/or 16 kDa antigens in 27 of the 30 CL patients' sera and in 39 of the 111 non-CL patients' sera (26 from the infectious diseases group, four from the autoimmune diseases group, and nine from the dermatology department). The method tested showed a high sensitivity (90%) and a low specificity (66%), and a diagnosis odds ratio of 17.5 (95% CI [4.6-78.0]). This IB may be helpful to exclude the diagnosis of CL, prompting physicians to look for another diagnosis in the case of a negative IB.

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.

Place of Serology in the Diagnosis of Zoonotic Leishmaniases With a Focus on Visceral Leishmaniasis Due to Leishmania infantum

Leishmaniases are a group of parasitic diseases transmitted through the bite of female phlebotomine sandflies. Depending on the Leishmania species, the reservoirs can be humans (anthroponosis) or different animals (zoonosis). Zoonotic leishmaniasis present several clinical forms in function of the species involved: visceral leishmaniasis (VL), cutaneous leishmaniasis (CL), and muco-cutaneous leishmaniasis (MCL). The biological diagnosis is of utmost importance because the clinical features are not specific. In addition to parasitological and molecular biology (polymerase chain reaction, PCR) assays, serology is routinely used for the diagnosis of leishmaniasis. Indeed, although PCR is more sensitive than serological assays, its implementation is limited to referral laboratories and research centers. Therefore, serology is still a key element for their diagnosis. Here, we discuss the different serological assays available for the diagnosis of zoonotic leishmaniasis. We will review the enzyme-linked immunosorbent assay, immunofluorescence antibody test, immunochromatography test (ICT), direct agglutination test, and western blot as well as the different diagnostic strategies in function of the clinical form (VL, CL, and MCL). We will also discuss the place of serology for detecting asymptomatic carriers and for the follow-up of VL. Depending on the laboratory, different assays can be used, from ICT, which is appropriate for field testing, to a combination of serological tests to improve the sensitivity.